Maxillary Implant-Supported Overdentures: Mechanical Behavior Comparing Individual Axial and Bar Retention Systems. A Cohort Study of Edentulous Patients

Background and objectives: To compare the medium- to long-term mechanical behavior of overdentures with two different retention systems: overdentures with Locator® axial retention, and vertical insertion overdentures with bar retention, used to rehabilitate edentulous maxillar. Material and Methods: This prospective study assessed patients presenting complete maxillary edentulism, rehabilitated by means of implant-supported overdentures (n = 20), 10 with Locator® axial retention (ODA group) and 10 with overdentures on bars (ODB group). Patients also completed a questionnaire to determine their satisfaction with treatment. Results: The mean follow-up time in both groups was 11.4 years, with follow-up times in both groups ranging from 5 to 14 years. The ODA group suffered mechanical complications such as retention loss, need for nylon retention insert changes, resin fracture, and need for relining. In the ODB group, prosthetic dental wear, screw loosening, and complete prosthetic failure were more common. A total of 19 implants failed (23.8%); of these, 11 were in the ODA group (failure rate = 27.5%) and eight in the ODB group (failure rate = 20%). The patient satisfaction questionnaire obtained a mean score of 7.9 out of 10 in the ODA group, and 9.75 in the ODB group. Conclusions: in rehabilitations of edentulous maxillar by means of implant-supported overdentures, both the systems assessed were shown to be effective in the medium to long term. Patients expressed a high level of satisfaction with the treatments received.

Prevalence of Dental Implants and Evaluation of Peri-implant Bone Levels in Patients Presenting to a Dental School: A Radiographic Cross-Sectional 2-Year Study

PURPOSE

To evaluate the number of patients with dental implants who present to a dental school clinic for screening and to report the prevalence of peri-implant bone level change detected on digital panoramic radiographs of those subjects.

MATERIALS AND METHODS

Patient screening files for 9,422 patients over a 2-year period were examined to see how many patients presented with dental implants. Those patients with at least one implant were further evaluated by measuring the bone level on the mesial and distal sides of the implant using the screening radiograph.

RESULTS

A total of 187 patients (2%) had at least one implant. In regard to implants, 423 were examined and 146 (33%) had no detectable bone loss defined as bone level below the top of the implant. When thresholds of bone loss were evaluated, 109 implants (25%) had ≥ 2 mm of bone loss on either the mesial or distal sides or both. The median bone loss was 1.74 mm for the 277 implants with detectable bone loss and 2.97 mm for the 109 implants that had ≥ 2 mm bone loss. Interestingly, patients who were ≥ 70 years of age had significantly (P = .03) more bone loss in the mandible compared with the maxilla, while patients who were 60 to 69 years of age had significantly greater loss in the maxilla.

CONCLUSION

These data reveal that for patients presenting to the dental school for a screening over a 2-year period, 1.98% had one or more dental implants. Furthermore, those patients with implants had a minimum amount of bone loss as measured from the top of the implant.

Epidemiology of Implant Mortality Disparity Among Intraoral Positions and Prosthesis Types

PURPOSE

To examine the disparity of single-crown implant failure with a similar loss of the splinted prosthesis in differing anatomical locations while controlling for other demographic and clinical variables that may confound the relationship between prosthesis types and implant loss.

MATERIALS AND METHODS

A multicenter retrospective cohort study was designed to include patients treated with dental implants from 2003 to 2014. The variables included age, sex, systemic disease, bone graft, implant placement date, position of dental implant, length of dental implant, diameter of dental implant, loading time, type of prosthesis, type of opposing occlusion, latest check date, and survival or loss of the dental implant. The demographic and clinical variables' influence on the survival of dental implants was estimated by the Kaplan-Meier method. The position and diameter were adjusted for the accurate estimation of the relationship between the prosthesis type and survival of the dental implant with the Cox proportional hazard method.

RESULTS

A total of 1,151 dental implants from 403 patients were ascertained. After adjusting for the confounding effect of position and diameter, single-crown prostheses were 38.1 (95% CI: 15.1-118) times more likely to be lost than the connected-type prostheses. For single-crown implants, the waiting time for osseointegration before loading was the highest for the maxillary molar position and the lowest for the mandibular molar position (P < .0001), while the most frequent implant loss occurred in the maxillary anterior area, and the second frequent area was the maxillary molar position; the lowest occurrence of implant loss was for the mandibular molar position. This disparity was statistically significant (P = .0271).

CONCLUSION

Despite the high survival rates of endosseous implants as a whole, since the variation of implant loss was observed among the different anatomical positions for single-crown implants, special attention has to be given to the maxillary anterior and maxillary molar positions. A longer healing time assuming compensation for disadvantageous bone quality was not directly effective in increasing implant longevity in the vulnerable positions.

Dental Implants in the Elderly Population: A Long-Term Follow-up

PURPOSE

The objectives of this study were to evaluate implant survival and success in the elderly population and to assess indicators and risk factors for success or failure of dental implants in older adults (aged 60 years and older).

MATERIALS AND METHODS

This historical prospective study was developed from a cohort of patients born prior to 1950 who received dental implants in a single private dental office. Implant survival and marginal bone levels were recorded and analyzed with regard to different patient- and implant-related factors.

RESULTS

The study examined 245 patient charts and 1,256 implants from one dental clinic. The mean age at the time of implant placement was 62.18 ± 8.6 years. Smoking was reported by 9.4% of the cohort studied. The overall survival rate of the implants was 92.9%; 7.1% of the implants had failed. Marginal bone loss depicted by exposed threads was evident in 23.3% of the implants. Presenting with generalized periodontal disease and/or severe periodontal disease negatively influenced the survival probability of the implant. Implants placed in areas where bone augmentation was performed prior to or during implant surgery did not have the same longevity compared with those that did not have augmentation prior to implantation.

CONCLUSION

The overall findings concluded that implants can be successfully placed in older adults. A variety of factors are involved in the long-term success of the implant, and special consideration should be taken prior to placing implants in older adults to limit the influence of those risk factors.

The Up-to-14-Year Survival and Complication Burden of 256 TiUnite Implants Supporting One-Piece Cast Abutment/Metal-Ceramic Implant-Supported Single Crowns

PURPOSE

To assess the estimated cumulative survival (ECS) and explore the technical and biologic complications of 256 TiUnite implants (Nobel Biocare) supporting one-piece cast abutment/metal-ceramic implant-supported single crowns (ISCs) in situ for up to 14 years.

MATERIALS AND METHODS

A prospective sequentially recruited cohort of 207 patients received 256 metal-ceramic ISCs on TiUnite implants between 2001 and 2014. All but 24 patients with 27 crowns were clinically evaluated between January 2014 and April 2015 in conjunction with or in addition to their tailored maintenance program. Radiographs were obtained, and any previously recorded treatments associated with the crowns were tabulated. The ECS and standard errors were calculated with the life table actuarial method and Greenwood's formula, respectively. The log rank test was applied to assess differences between anterior and posterior crowns. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. Independent groups were compared with the Mann-Whitney U test and related groups with the Wilcoxon Signed Rank Test.

RESULTS

The mean clinical service time of the crowns was 5.61 years (44 ≥ 10 years). The 14-year ECS was 95.95% ± 3.20% with no significant difference between anterior and posterior prostheses. Only seven implants lost marginal bone ≥ one thread from the time of crown insertion. There were 30 nonterminal complications (16 biologic, 14 mechanical). The associated economic burden was low (n = 35 TAUs).

CONCLUSION

High gold-alloy one-piece cast abutment/metal-ceramic ISCs on TiUnite implants exhibited excellent longevity and few complications over 14 years.

Prevalence of peri-implantitis in patients with implant-supported fixed prostheses

OBJECTIVE

The purpose of this study was to evaluate periimplantitis prevalence in patients using implant-supported fixed prostheses that did not have any routine maintenance care.

METHOD AND MATERIALS

A total of 161 implants (27 patients) were evaluated in patients using implant-supported fixed prostheses. Collected data included information related to patient general health and local factors such as characteristics of implants, time in function, type of loading, positioning, Modified Bleeding Index, bacterial plaque, bleeding on probing (BOP), marginal recession, probing depth (PD), keratinized mucosa, and radiographic bone loss (BL). Factors related to the prostheses were also evaluated. The exclusion criteria were patients that have had any follow-up visit for plaque control of the prosthesis and/or the implants.

RESULTS

From a total of 161 implants, 116 (72%) presented without peri-implantitis (PD > 4 mm + BOP + BL > 2 mm) while 45 (28%) had some sign of the disease. Implants placed in the maxilla were 2.98 times more likely to develop the disease (P < .05). Moreover, patients aged ≤ 60 years old were 3.24 times more likely to develop peri-implantitis (P < .05). Another analysis with statistical relevance (P < .05) was that implants with less than 3 mm interimplant distance were three times more likely to have peri-implantitis. There was no statistical relevance considering other analyses.

CONCLUSION

It can be concluded that patients aged ≤ 60 years have a greater chance of presenting periimplantitis, as well as for implants positioned in the maxilla and those placed with an interimplant distance < 3 mm.

A long-term retrospective analysis of survival rates of implants in the mandible

PURPOSE

To retrospectively analyze the survival rate of endosseous dental implants placed in the edentulous or partially edentulous mandible over a long-term follow-up period of 10 years or more.

MATERIALS AND METHODS

The charts of patients who underwent mandibular implant placement at a private prosthodontics practice and received follow-up care for 10 years or more were included in this study. Implants were examined according to the following study variables: patient sex, patient age, degree of edentulism (fully vs partially edentulous), implant location, time of loading (delayed vs immediate), implant size and type, bone quality, prosthesis type, and the presence of other implants during placement.

RESULTS

The study sample was composed of 2,394 implants placed in 470 patients with 10 to 27 years of follow-up. Of these 2,394 implants, 176 failed, resulting in an overall cumulative survival rate (CSR) of 92.6%. A total of 1,482 implants were placed in edentulous mandibles, and 912 implants were placed in partially edentulous mandibles, with CSRs of 92.6% and 92.7%, respectively. Comparisons of the study variables with respect to CSR were largely nonsignificant. However, there were significant differences in CSRs between anterior vs posterior locations and rough- vs smooth-surfaced implants in addition to some prosthesis types, ages, and bone qualities. The overall CSR of 92.6% in the present study is high and comparable to survival rates observed in previous long-term analyses of mandibular implants. The significant differences observed between implant locations, patient age groups, bone qualities, and prostheses were not suggestive of any remarkable trends.

CONCLUSION

Patient sex, age, degree of edentulism, implant location, time of loading, implant size and type, bone quality, prosthesis type, and the presence of multiple implants did not result in any significant effect on long-term implant survival. The CSR observed after 10 to 27 years of follow-up in a single private prosthodontic center was high (92.6%) and supports the use of endosseous dental implants as a long-term treatment option for the rehabilitation of the edentulous and partially edentulous mandible.

Three-Year Analysis of Fixed and Removable Telescopic Attachment-Retained Implant-Supported Dental Prostheses: Survival and Need for Maintenance

PURPOSE

The purpose of this retrospective clinical study was to evaluate the clinical outcomes of fixed implant-supported dental prostheses (FISDPs) and removable ISDPs (RISDPs) retained by telescopic attachments, the factors influencing survival, and the type and number of maintenance treatments required during the observation period.

MATERIALS AND METHODS

This retrospective clinical study is based on patients who were provided with ISDPs between 2004 and 2010. Patient sex, type of prosthesis, location, opposing dentition, and the effect of continuous follow-up on the probability of a favorable outcome, as well as the number of maintenance treatments, were analyzed. A statistical analysis was performed using the Kaplan-Meier method.

RESULTS

A sample of 233 patients with 157 FISDPs and 76 RISDPs supported by a total of 567 implants was randomized and included in the analysis. The mean observation period was 15.9 ± 15.4 months (maximum, 66.0 months). During the observation period, 3.9% of prostheses (7/157 FISDPs and 2/76 RISDPs) ceased to function and 2.3% of implants (13 implants) were lost. The mean survival time was 59.7 ± 2.3 months, with a survival probability of 90.2% after 3 years. Prostheses in the mandible showed significantly higher survival rates than those in the maxilla. Maintenance treatments had to be performed at an earlier stage for patients with RISDPs than for patients with FISDPs. In patients with a conventional removable prosthesis in the opposing arch, the time until maintenance was needed was significantly shorter.

CONCLUSION

Within the limitations of a retrospective study, it can be concluded that the FISDPs and RISDPs show equally good survival rates after 3 years in function. RISDPs showed a greater and earlier need for maintenance treatments during the first years in function.

Systematic review of the survival rate and incidence of biologic, technical, and esthetic complications of single implant abutments supporting fixed prostheses

PURPOSE

To assess the 5-year survival rate and number of technical, biologic, and esthetic complications involving implant abutments.

MATERIALS AND METHODS

Electronic (Medline) and hand searches were performed to assess studies on metal and ceramic implant abutments. Relevant data from a previous review were included. Two reviewers independently extracted the data. Failure and complication rates were analyzed, and estimates of 5-year survival proportions were calculated from the relationship between event rate and survival function. Multivariable robust Poisson regression was used to compare abutment characteristics.

RESULTS

The search yielded 1,558 titles and 274 abstracts. Twenty-four studies were selected for data analysis. The survival rate for ceramic abutments was 97.5% (95% confidence interval [CI]): 89.6% to 99.4%) and 97.6% (95% CI: 96.2% to 98.5%) for metal abutments. The overall 5-year rate for technical complications was 11.8% (95% CI: 8.5% to 16.3%), 8.9% (95% CI: 4.3% to 17.7%) for ceramic and 12.0% (95% CI: 8.5% to 16.8%) for metal abutments. Biologic complications occurred with an overall rate of 6.4% (95% CI: 3.3% to 12.0%), 10.4% (95% CI: 1.9% to 46.7%) for ceramic, and 6.1% (95% CI: 3.1% to 12.0%) for metal abutments.

CONCLUSIONS

The present meta-analysis on single-implant prostheses presents high survival rates of single implants, abutments, and prostheses after 5 years of function. No differences were found for the survival and failure rates of ceramic and metal abutments. No significant differences were found for technical, biologic, and esthetic complications of internally and externally connected abutments.

Retrospective multicenter study of 230 6-mm SLA-surfaced implants with 1- to 6-year follow-up

PURPOSE

Using short implants poses a challenge in implant surgery. Implant surfaces have evolved, making it possible to improve the success of short implants substantially. However, there is still little information about the long-term predictability achieved with short, rough-surfaced implants. The objective of this study was to evaluate the long-term survival rate of 6-mm rough implants.

MATERIALS AND METHODS

A retrospective multicenter analysis of the survival of short 6-mm SLA-surfaced implants was conducted. A total of 230 implants placed in 159 patients were included. The follow-up time ranged between 1 and 6 years.

RESULTS

Seven of the 230 implants failed, which gives a cumulative survival rate of 96.4%. Two hundred and fourteen implants were placed in the mandible (93.1%), as opposed to 16 placed in the maxilla (6.9%). Five implants failed during the osseointegration period, and two failed after receiving the prosthetic load. No statistically significant differences were found (P < .44). Of the loaded implants, 209 were splinted to other implants, as opposed to 14 that were not. One implant failed in each group, resulting in a 99.5% for the splinted implants and 92.9% for the unsplinted implants. No statistically significant differences were found between the splinted and unsplinted groups (P < .12).

CONCLUSIONS

The short implants used in this study displayed high longterm predictability when placed in the mandible and splinted. There is insufficient- information to extrapolate these results to the maxilla and non-splinted implants.

Use of implant-supported prostheses in edentulous mandibles among prosthodontists in Sweden

The aim of this study was to investigate the production of mandibular implant-supported fixed and removable prostheses among prosthodontic specialists in Sweden and to compare the results with findings in a similar study made in 2001 (17). Questionnaires regarding treatment with mandibular implant prostheses during 20011 were mailed to all specialists in prosthodontics in Sweden (n = 156, according to available data). Of the 156 questionnaires, 129 (83%) were returned and of those 114 were completed. The reported number of treatments with mandibular implant-supported prostheses varied much among the specialists. Fixed implant prostheses were more common than overdentures (means 11 and 3, median values 8 and 2, respectively). However, the range was large for both alternatives. Ten (9%) of the specialists reported no treatment with fixed implant prostheses while 29 (25%) had not made any implant overdenture during 2011. The most common anchorage system for overdentures in 2011 (as well as in 2001) was two un-splinted implants with ball attachments or Locator abutments. The most common reasons for choosing overdenture treatment instead of a fixed implant prosthesis in 2011 were the reduced cost and the patient's main wish to improve denture retention. A majority of the prosthodontists (58%) reported that patients with implant overdentures were as satisfied as those with fixed implant-supported prostheses, whereas 40% claimed they were less satisfied. Two respondents (2%) considered that overdenture patients were more satisfied than those with a fixed prosthesis. It can be concluded that the general attitude among Swedish prosthodontists towards implant overdentures has not changed much during the 10-year period between the present and the previous investigation.An overdenture is still a seldom-used option in implant treatment of patients with edentulous mandibles in Sweden. Instead, a fixed implant-supported prosthesis continues to be the preferred option,

A retrospective comparison of 1,022 implants: immediate versus nonimmediate

PURPOSE

The aim of this study was to compare the survival of implants placed in mature bone with the survival of implants placed in fresh extraction sockets in the same patients.

MATERIALS AND METHODS

A retrospective study of patients treated simultaneously with at least one immediate and one nonimmediate implant was carried out for the period 2005 to 2008. Data were recorded for patient age and sex; implant length, diameter, and position; and, for postextraction implants, distance between the implant and the alveolar bone.

RESULTS

One thousand twenty-two implants were placed in 150 patients; 480 were placed immediately and 542 were placed in mature bone. The mean implant survival rate was 93.4%; survival rates were 93.8% for immediate implants and 93.2% for nonimmediate implants. The failure rate in the maxilla was 5.2% and in the mandible it was 2.8%. The failure rate for immediate implants in the posterior maxilla was 8.5%, which was statistically significantly higher than for implants placed elsewhere. Of the failed implants, 72% were early failures.

CONCLUSIONS

The survival rate of implants placed in fresh extraction sockets was similar to that of implants placed in mature bone. A statistically significantly higher failure rate was seen with immediate implants placed in the posterior maxilla.

An inventory of mandibular fractures associated with implants in atrophic edentulous mandibles: a survey of Dutch oral and maxillofacial surgeons

PURPOSE

The present study provides an inventory of the number of fractures that occurred in conjunction with implant placement in edentulous patients in the Dutch population from 1980 to 2007 and estimates the incidence with which this might occur. The study also sought to define the factors that increase the risk of fracture.

MATERIALS AND METHODS

Questionnaires were sent to all 198 oral and maxillofacial surgeons working in 56 hospitals in the Netherlands. Questions were asked regarding the causes of fractures, the height of the edentulous mandible, and the methods of fracture treatment.

RESULTS

Responses were received from 53 of the 56 departments. During the study period, 157 edentulous mandibles fractured in conjunction with implant treatment. All fractures occurred in mandibles with less than 10 mm of height, as measured in the symphysis. An incidence of less than 0.05% was estimated based on an estimated number of 475,000 patients treated with at least two implants during this time to support an overdenture. Reasons for early implant failures were insufficient bone volume, iatrogenic causes, nonintegration, and a narrow arch. Peri-implantitis, trauma, and explantation were associated with fractures occurring 1 year or more after implant placement. Several methods were employed to treat the fractured mandibles, including closed reduction, rigid fixation using osteosynthesis plates, and bone grafts with fixation. In 52% of patients, fracture healing was uneventful; however, in 48% of patients, complications were encountered, including osteomyelitis, nonunion, plate fracture, screw loosening, and dehiscences with subsequent infections.

CONCLUSIONS

Mandibles with a height of 10 mm or less, as measured at the symphysis, are at risk of fractures and associated complications. The provision of proper informed consent regarding the advantages and disadvantages of placing implants in thin mandibles is essential.

Demographics of implant placement and complications of a patient subgroup in a dental hospital population

STATEMENT OF PROBLEM

Little has been reported about the demographics of implant placement in the Irish population and the complications that occur. This is important in terms of service planning and providing patient information.

PURPOSE

The purpose of this study was to construct a database of patients who had implants placed in the Dublin Dental School et Hospital from 2000 to 2006. Also, we wanted to compare the complications that occurred in patients who had overdentures to those with a fixed prosthesis.

METHODS

Hospital records were searched for all patients who had implants placed over a seven-year period and we recorded demographic information, as well as details of the implant site, implant type and restoration. Patients who had four or more implants placed for an implant-supported overdenture or fixed prosthesis were invited to attend for a clinical examination.

RESULTS

A total of 1,111 implants were placed in 452 patients over the study period--half of the implants supported single crowns, while the other half supported mainly overdentures and full arch fixed prostheses, with few fixed partial dentures. The 40- to 60-year-olds had the greatest number of implants placed of any age group and most implants were placed in the anterior region. Patients with implant-supported overdentures recorded more complications (52%) compared to those with fixed prostheses (32%). The most common complications associated with both treatments were gingival inflammation and peri-implant mucositis. Overdentures additionally had a significant number of retentive clip fractures.

CONCLUSIONS

Implant-supported overdentures and fixed prostheses were both clinically successful. However, patients and clinicians should be aware that soft tissue and mechanical complications are common.

Mandibular implant overdentures followed for over 10 years: patient compliance and prosthetic maintenance

PURPOSE

The mandibular implant overdenture is a popular treatment modality and is well documented in the literature. Follow-up studies with a long observation period are difficult to perform due to the increasing age of patients. The present data summarize a long-term clinical observation of patients with implant overdentures.

MATERIALS AND METHODS

Between 1984 and 1997, edentulous patients were consecutively admitted for treatment with an implant overdenture. The dentures were connected to the implants by means of bars or ball anchors. Regular maintenance was provided with at least one or two scheduled visits per year. Recall attendance and reasons for dropout were analyzed based on the specific history of the patient. Denture maintenance service, relining, repair, and fabrication of new dentures were identified, and complications with the retention devices specified separately.

RESULTS

In the time period from 1984 to 2008, 147 patients with a total of 314 implants had completed a follow-up period of >10 years. One hundred one patients were still available in 2008, while 46 patients were not reexamined for various reasons. Compliance was high, with a regular recall attendance of >90%. More than 80% of dentures remained in continuous service. Although major prosthetic maintenance was rather low in relation to the long observation period, visits to a dental hygienist and dentist resulted in an annual visit rate of 1.5 and 2.4, respectively. If new dentures became necessary, these were made in student courses, which increased the treatment time and number of appointments needed. Complications with the retention devices consisted mostly of the mounting of new female retainers, the repair of bars, and the changing of ball anchors. The average number of events and the rate of prosthetic service with ball anchors were significantly higher than those with bars. Twenty-two patients changed from ball anchors to bars; 9 patients switched from a clip bar to a rigid U-shaped bar.

CONCLUSIONS

This long-term follow-up study demonstrates that implant overdentures are a favorable solution for edentulous patients with regular maintenance. In spite of specific circumstances in an aging population, it is possible to provide long-term care, resulting in a good prognosis and low risk for this treatment modality. For various reasons the dropout rate can be considerable in elderly patients and prosthetic service must be provided regularly.

Clinical experience of residents with RPD treatment in U.S. graduate prosthodontics programs

This cross-sectional study was conducted to quantify the clinical experience of prosthodontic residents with cast metal removable partial denture (RPD) treatment based on their year of training, geographic location of the program, and nature of the program. A web-based survey consisting of five questions was e-mailed to program directors from forty-two programs across the United States. A 62 percent response rate was obtained (26/42). Thirteen of the programs (50 percent of respondents) stipulated a specific number of RPDs to be done prior to completion of the program. Clinical experience of residents varied vastly based on year of training, geographic location of the program, and nature of the program. Prosthodontic residents from southern states, university-based programs, and public school programs had more clinical experience than residents from other programs. The average clinical experience for a prosthodontic resident during three years of training was eight traditional RPDs and two implant-supported RPDs. This is the first study done exploring this topic and provides baseline information on residents' clinical experience in RPD treatment. Future studies will determine educational trends and reassess this portion of the curriculum in graduate prosthodontics.

Outcome of dental implants in patients with and without a history of periodontitis: a 5-year pragmatic multicentre retrospective cohort study of 1727 patients

AIM

To evaluate the outcome of dental implants placed in patients with a history of periodontitis. Patients with no or mild history of periodontitis served as controls.

MATERIALS AND METHODS

A total of 1727 patients were consecutively treated in four private practices. Patients were divided into three groups according to their initial periodontal conditions assessed with a modified periodontal screening and recording (PSR) index: 630 patients were in the severe periodontitis (SP) group, 839 in the moderate periodontitis (MP) group, and 258 had no periodontitis (NP). Patients requiring periodontal treatment were treated prior to implantation. Various implant systems and procedures were used. In total, 3260 implants and 1707 implant-supported prostheses were placed in the SP group, 2813 implants and 1744 implant-supported prostheses in the MP group, and 647 implants and 424 implant-supported prostheses in the NP group. Mixed implant–tooth supported prostheses (98 prostheses in 89 patients) were not considered. Outcome measures were prosthesis and implant survival.

RESULTS

Two-hundred and fifty patients were lost to follow-up 5 years after loading. Regarding prosthesis failures, 13 prostheses could not be placed or failed in 13 patients of the SP group (0.8%), 11 prostheses could not be placed or failed in 9 patients of the MP group (0.7%), and 3 prostheses failed in 3 patients of the NP group (0.9%). For implant failures, 130 (4.5%) implants failed in the SP group, 74 (3.1%) implants failed in the MP group, and 15 (3.0%) implants failed in the NP group. Most of the implant failures (90%) occurred before implant loading. Fitting a logistic regression for early implant failures and total implant failures, taking into account the clustering of implants in patients, there were no statistically significant differences between the three PSR groups (P > 0.05).

CONCLUSIONS

Owing to the retrospective nature of this study, conclusions need to be interpreted with caution. A previous history of periodontal disease may not have a significant impact on implant failures up to 5 years after loading.

[Status report on dental implantology in Switzerland]

PURPOSE

To present results of a survey on the status of implantology in Switzerland.

MATERIALS AND METHODS

A questionnaire was sent to all SSO (Swiss Dental Society) members asking for personal (anonymous) background data and their implantology concepts. Specific questions dealt with level of recognition of implants, use of implants, superstructures, success and failure rates, recall and training.

RESULTS

Straumann, Nobel Biocare, 3i, SPI and Frialit are the most commonly used implant systems in Switzerland. Almost two thirds (63.8%) of the dentists place more than 20 implants per year. Long-term prognosis is the crucial factor, whereas material costs play a minor role. The edentulous lower jaw is the indication of choice, whereas the edentulous upper jaw applies less. Almost every dentist active in implantology follows continuing education programs in the field.

CONCLUSION

Compared to a study undertaken twelve years ago the number of dentists engaged in implantology doubled, meaning at least one third of non-hospital dentists in Switzerland are involved in dental implantology. Overall the willingness to extend the therapeutic range has greatly increased.

Status report on dental implantology in Switzerland in 2006. A cross-sectional survey

PURPOSE

To present results of a survey on the status of implantology in Switzerland in 2006.

MATERIALS AND METHODS

A questionnaire was sent to all SSO (Swiss Dental Society) members asking for personal (anonymous) background data and their implantology concepts. Specific questions dealt with level of recognition of implants, use of implants, superstructures, success and failure rates, recall and training.

RESULTS

A total of 1568 (47.3%) of the 3315 questionnaires were returned. Straumann, Nobel Biocare, 3i, SPI and Frialit were the most commonly used implant systems in Switzerland. Almost two-thirds (63.8%) of the dentists placed more than 20 implants per year. Long-term prognosis was the crucial factor, whereas material costs played a minor role. The edentulous mandible was the indication of choice, whereas the edentulous maxilla applied less. Almost every dentist active in implantology followed continuing educations programs in the field.

CONCLUSIONS

Compared to a study undertaken 12 years ago, the number of dentists engaged in implantology doubled, meaning at least one-third of non-hospital dentists in Switzerland were involved in dental implantology. Overall, willingness to extend the therapeutic range has greatly increased.

A methodology to study the effects of prosthesis misfit over time: an in vivo model

PURPOSE

Passive fit of implant-supported superstructures cannot currently be achieved. The aim of this investigation was to create a methodology that can be used to study the effects of prosthesis misfit in humans.

MATERIALS AND METHODS

An edentulous patient received two interforaminal implants and a screw-retained bar for the retention of the mandibular denture. A corresponding in vitro model with strain gauges placed mesially and distally, adjacent to the implants, was fabricated to serve as a standardizing control. Over a period of 6 months, a total of 10 measurements on both the in vitro model and in the patient's mouth were conducted with newly fixed strain gauges on the bar.

RESULTS

The in vitro experiments showed that no component wear at the abutment-bar interface had occurred and that repositioning of the strain gauges on the bar caused deviations in strain measurements up to 10.55%. In vivo, a reduction in strain development, from 445 to 383 Mum/m, was observed in the initial phase up to 12 weeks after bar insertion. Subsequently, the measurement values increased, and after a period of 24 weeks, they nearly reached the initial strain level (443 microm/m). Only minor changes in strain development of the bar could be detected; these might be a result of limited dynamic loading and the cortical architecture of the surrounding bone. Deviations in measurement accuracy caused by repositioning of the bar strain gauge are a limitation of this technique and should be eliminated in future studies.

CONCLUSIONS

The present methodology can be applied to study changes in static implant loading over time in humans.

Changes in patient and FDP profiles following the introduction of osseointegrated implant dentistry in a prosthodontic practice

PURPOSE

This paper describes the effects of implant-related dentistry on patient profiles and the types of fixed dental prostheses provided in clinical practice.

MATERIALS AND METHODS

All implant- and tooth-supported prostheses provided in a prosthodontic practice between 1984 and 2007 were tabulated. Incidence was analyzed in relation to gender, age at time of prostheses insertion, and prostheses type.

RESULTS

Tooth-supported single crowns (TSCs) and tooth-supported fixed dental prostheses (TFDPs) were involved in 97% of treatments requiring fixed dental prostheses from 1984 to 1991. From 1991 to 2007, however, a marked increase in the number of implants restored directly corresponded with a decrease in the number of TFDPs so that by 2007, implant-supported fixed dental prostheses (IFDPs) accounted for 81% of all tooth replacements. Between 1984 and 2007 the incidence of TFDPs was 61% in females and 39% in males, whereas the incidence of IFDPs was 55% in females and 45% in males. IFDPs were also involved in 35% of restorations in patients under 31 years of age and TFDPs in 19%. In the under-21 years age group, IFDPs were more common in females (9%) than males (4%), but in the 21 to 30 years age group they were more common in males (21%) than females (13%). There was a decrease in three-unit TFDPs, in TFDPs with four or more pontics and those not satisfying Ante's Law, and in teeth used that had been subjectively assessed to have an unfavorable 10-year prognosis at the time of prosthesis insertion.

CONCLUSIONS

The incorporation of osseointegrated implant dentistry into a clinical practice has resulted in changes in the patient profile and type of fixed dental prostheses provided, including a decrease in the use of TFDPs; an increase in the referral of patients under 31 years of age; a decrease in three-unit, long-span, and complex TFDPs; and a decrease in tooth abutments assessed to be structurally or biologically compromised.

Implant-supported mandibular overdentures retained with a milled bar: a retrospective study

PURPOSE

The aim of this retrospective study was to evaluate implant survival rate, peri-implant conditions, and prosthodontic maintenance for implant-supported mandibular overdentures rigidly retained with a milled bar.

MATERIALS AND METHODS

Patients with 4 interforaminal implants (cylindric or screw-type) supporting an overdenture on a milled bar treated between 1996 and 2004 were asked to participate in a retrospective study. The cumulative implant survival rate and peri-implant conditions (marginal bone loss, pocket depth, Plaque Index, Gingival Index, Bleeding Index, and calculus presence) were evaluated and compared between cylindric and screw-type implants. The incidence and type of prosthodontic maintenance and subjective patient satisfaction rating were also evaluated.

RESULTS

Fifty-eight of 67 patients (87.3%) and 232 implants (76 cylindric, 156 screw-type) were available for follow-up examination after a mean period of 59.2 +/- 26.9 months. The cumulative implant survival rate was 99%, and no differences in peri-implant soft tissue conditions were noted between the different implant types used. The cylindric implants showed more pronounced marginal bone resorption than the screw-type implants (1.9 +/- 0.6 mm vs 2.2 +/- 0.6 mm; P = .02) but the difference was not clinically significant. A low incidence of prosthodontic maintenance evenly distributed throughout the overall follow-up period and a high subjective satisfaction rating by the patients were noted.

CONCLUSION

Interforaminal screw-type and cylindric implants supporting a milled bar for rigid overdenture anchorage were associated with a high survival rate and excellent peri-implant conditions. The incidence of prosthodontic maintenance was low and evenly distributed throughout the follow-up period as a result of rigid denture stabilization by the milled bar. Rigid anchorage of a mandibular overdenture with a milled bar unites the prosthodontic advantages of removable and fixed prostheses. (Clinical Trial) (More than 50 references.)

Long-term follow-up of hydroxyapatite-coated dental implants--a clinical trial

PURPOSE

The purpose of this study was to report the long-term (8- to 10-year) results of hydroxyapatite (HA) -coated dental implants and compare them to the 5-year results as well as to long-term results of both HA and titanium dental implants reported in the literature.

MATERIALS AND METHODS

Patients were recruited, screened, and accepted or rejected sequentially based on specific inclusion/exclusion criteria. Implant placement was performed according to the manufacturer's instructions, followed by prosthetic reconstruction. Routine follow-up examinations were performed for a 5-year period. At 10 years all patients were contacted by mail and invited to participate in a longer-term follow-up of dental implants. All participants provided informed consent and underwent a complete history, including clinical and radiographic examination. The data obtained were statistically analyzed using life tables.

RESULTS

A total of 302 implants were placed in 90 patients whose average age was 54.3 years (SD 13.2 years). Of these, 114 implants in 40 patients were examined at 10 years, 88 in the mandible and 26 in the maxilla. The cumulative survival rate was 85.40% in the mandible and 70.59% in the maxilla. The total survival rate was 81.97%.

CONCLUSIONS

The 10-year success rate of HA-coated dental implants was 82%. The success rate is higher in the mandible as compared to the maxilla. The 10-year results are inferior to the 5-year results. (Clinical Trial)

Implants for life? A critical review of implant-supported restorations

AIM

This review critically appraises the literature on implant-supported restorations.

METHOD

The review was conducted in March 2007 using OVID Medline with the search terms, limited to the English Language, of implant, crown, bridge, fixed and removable partial dentures and complete dentures. From a total of 5135 papers combining implants and implant-supported restorations only 131 were found, after a thorough hand search, to be relevant to the restoration of implants.

RESULTS

The outcome of implant fixtures have consistently been shown to be successful over the long-term. However, the same focus of research into the restorations used to support implants has not. Where research is available to guide clinicians towards a particular technique the rigour of the research is limited.

CONCLUSION

More emphasis by the research community on the outcome of restorations supported by implants is needed.

Dental state, prosthodontic treatment and chewing ability ? a study of five cohorts of 70-year-old subjects

The aim was to study the relationship between dental state, prosthetic rehabilitation and chewing ability in 70-year-old subjects examined between 1971 and 2001. Five birth cohorts born in 1901/1902 (I), 1906/1907 (II), 1911/1912(III), 1922 (V), and 1930 (VI) were examined at 70 years of age. The number of participants in the odontological cohorts varied between 386 and 583. The prevalence of total edentulism changed from 51% in cohort I to 7% in cohort VI. The proportion of subjects using removable dentures decreased from 76% to 17%, whereas those with >or=20 teeth increased from 13% to 65%. The prevalence of subjects with fixed partial dentures increased from 26% to 58%. Of the 70-year-old subjects examined in 2001, 5% had implant-supported restorations. The self-assessed chewing ability showed only weak associations with dental state, and there was no significant cohort trend. When all cohorts were pooled together, 80% considered their chewing ability good, 16% less good and 4% poor. Among the edentulous subjects, more individuals complained about poor chewing ability in the last two cohorts than in the first three. It was concluded that there were great differences in dental state between the five cohorts of 70-year-old subjects examined from 1971 to 2001. Edentulism and wearing of removable dentures decreased substantially, whereas the proportion of subjects with fixed partial dentures showed a marked increase. In spite of the improved dental state, the self-assessed chewing ability exhibited only minor variation over time.

Dentist communication with the dental laboratory for prosthodontic treatment using implants

PURPOSE

A questionnaire was sent to U.S. dental laboratories to evaluate the level of communication between dentists and laboratory technicians and to determine trends in procedures and materials used in fixed and removable implant restorations.

METHODS AND MATERIALS

Dental laboratories were randomly chosen from the National Association of Dental Laboratories for each of the 50 states. The questionnaire was mailed to the laboratory directors for 199 dental laboratories. One hundred fourteen dental laboratories returned the survey, yielding a response rate of 57%. Of those laboratories, 37 indicated that they did not participate in the fabrication of fixed implant restorations, yielding a response rate of 39%. Forty-two dental laboratories indicated that they did not participate in the fabrication of implant-retained overdenture prostheses, yielding a response rate of 36%.

RESULTS

Results from this survey show inadequate communication by dentists in completing work authorization forms. Custom trays are used more frequently for implant-retained overdenture impressions and stock trays for impressions of fixed implant prostheses. Poly(vinyl siloxane) is the material most commonly used for both fixed and removable implant-supported prostheses. Two implants with stud attachments are used more widely than those with bar attachments for implant-retained overdentures.

CONCLUSIONS

Most laboratories working on implant prosthodontic cases report inadequate communication between the laboratory and dentists related to materials and techniques used in fabrication of implant restorations.

Fixed partial prostheses supported by 2 or 3 implants: a retrospective study up to 18 years

PURPOSE

The purpose of this study was to evaluate and compare the long-term performance of fixed partial prostheses supported by 2 or 3 implants.

MATERIALS AND METHODS

All patients treated with fixed partial prostheses supported by either 2 or 3 implants during the period 1985 to 1998 were included in this retrospective report. Annual clinical follow-up examinations were performed, with special attention to stability of the prostheses and peri-implant and occlusal conditions. Radiographic examination was performed when the prostheses were delivered (year 0) and subsequently at 1-year, 5-year, and 10-year examinations.

RESULTS

A total of 178 patients had received fixed partial prostheses (FPPs) during this period of whom 123 (77 women and 46 men) were available for follow-up (mean age = 65 years, range 32-91). These 123 patients received a total of 146 implant-supported FPPs (63 two-implant- and 83 three-implant-supported) supported by 375 implants. The mean observation periods for the 2- and 3-implant-supported restorations were 9.6 years and 9.4 years (range, 5 to 18 years), respectively. Survival rates for the 2- and 3-implant-supported prostheses were 96.8% and 97.6%, respectively. The implant survival rate after loading was 98.4% for both groups. The mean bone loss at the 5-year follow-up was 0.3 mm for the 2 groups. No significant differences in bone loss (P > .05), implant failure rate (P > .05), or incidence of mechanical complications (P > .05) were found between the 2 prosthesis designs. The complications differed, significantly, with more loose gold and abutment screws in the 2-implant-supported group (P < .05) and more porcelain fractures in the 3-implant-supported group (P < .05).

CONCLUSION

The 2-implant-supported partial prostheses exhibited long-term clinical performance comparable to prostheses supported by 3 implants.

Low-cost implant overdenture option for patients treated in a predoctoral dental school curriculum

In an effort to make the implant overdenture more affordable for patients, a pricing package at the University of Alabama at Birmingham School of Dentistry was established. This package includes two implants, two dentures (upper and lower), and two implant abutments, all for $975. It is known as the "2-2-2" implant program. One concern regarding the program was whether patients would complete overdenture treatment or simply receive implants at this relatively low cost and have the implants restored outside the school. The purpose of this retrospective chart review was to determine how many patients in 2004 received implants as part of this program and how many of these patients completed overdenture treatment. Other data (age, distance from school, number of teeth at start of treatment, and gender) were collected to identify variables that might be associated with greater likelihood of completing overdenture treatment. In 2004, fifty-one patients received 102 implants as part of this program. Two patients had a failed implant prior to restoration (two of 102 implants), and one patient was referred to graduate prosthodontics for restoration. Of the remaining forty-eight patients, forty-one completed overdenture treatment (85 percent), and seven (15 percent) were lost to follow-up. The mean age of patients receiving this treatment was 60.7 years. The mean distance traveled to the school was 70.7 miles. While no variables showed significant predictive value, point estimates (estimate of the odds ratio) suggest that older patients and patients who travel greater distance to the school were less likely to complete treatment. The low-cost implant overdenture has been an important addition to our curriculum. The majority of patients who receive implants as part of this program complete overdenture treatment.

Implant Treatment in an Urban General Dentistry Residency Program: A 7-year Retrospective Study

Survival rates of multiple implant designs placed in various clinical situations average more than 90%. However, little data have been published on the survival rates of implants placed in dental residency programs. This study reports on the outcome of dental implants placed by first-year general dentistry residents in the University of Florida College of Dentistry–Jacksonville Clinic. The patients for this study received both surgical and restorative implant therapy from 1998 to 2005. A total of 263 patients (147 women, 116 men) were treated with dental implants. On average, a patient was 55.5 years old and received 3 implants. A variety of simple and complex restorative procedures were performed. Advanced general dentistry residents in conjunction with supervisory faculty treated all cases. The cumulative implant survival was 96.6%. Follow-up varied from 6 months to 7 years after placement. Cases included implants not yet loaded as well as implants loaded for 6 years or more. The findings of this study compare favorably with published studies and were unexpected in light of the residents' limited clinical experience.

A long-term study of implants supporting overdentures as a model for implant success

BACKGROUND

Implant-supported overdentures have been a common treatment for edentulous patients for the past 20 years, achieving good clinical results. The purpose of this study was to examine survival and success rates of implants supporting overdentures in the maxilla and mandible and to examine the influence of factors related to patients, implant procedure, implant data, and follow-up period on implant success.

METHODS

During a 10-year period (1990 to 2000), 285 implants were placed in 62 patients to support 69 overdentures (seven patients had overdentures in both jaws). Patients ranged in age from 45 to 85 years (mean 64.5 years). The files of 61 patients, including 277 implants supporting 68 overdentures (14 maxillary and 54 mandibular), had measurable radiographic post-exposure follow-up (range 6.63 to 110.93 months, mean 37.93 months) for cervical bone loss (CBL) measurements. Bone loss was measured by radiographic examination in which the mean number of exposed threads in mesial and distal sides of the implant was considered. Implants were rehabilitated by overdentures with bar (N = 52) or ball (N = 16) attachments.

RESULTS

Implant survival rate was 96.1% (11/285 did not survive) and total 10-year cumulative survival rate was 95.4% (maxilla, 83.5%, mandible, 99.5%). The success rate was 70.4% (maxilla, 41.9%; mandible, 80.8%) when using Albrektsson et al. success criteria. A logistic regression analysis showed that the maxilla (P <0.0001) and a short follow-up period (up to 5 years) (P = 0.017) were the most influencing factors enhancing CBL.

CONCLUSIONS

1) Survival of implants supporting overdentures was very high; 2) implants supporting overdentures in the maxilla had greater CBL than in the mandible; and 3) new criteria of implant success should be considered.

Dental implant use in New Zealand in 2004

OBJECTIVE

To investigate the characteristics of dental implant providers in New Zealand, to evaluate providers' dental implant treatment strategies, and to determine the nature of barriers to implant usage in New Zealand.

DESIGN

A postal survey questionnaire was sent to all registered dentists in New Zealand (N=1590).

METHOD

Data were analyzed with the SPSS statistical package.

RESULTS

Replies were received from 1005 (63.2 percent) of the surveyed dentists. The majority of dentists (76.2 percent) are interested in dental implants and promote them in their practices. Implant dentistry is performed by 49.5 percent of the respondents, with the prosthodontic aspects of implant dentistry are performed by 79.5 percent of these dentists, while the surgical stage is referred to specialists in 89.0 percent of the cases. The greatest barrier to dental implant treatment is cost. Implant dentistry is most often provided when there is financial support from ACC.

CONCLUSIONS

The extent of dental implant use in New Zealand is still relatively limited. Dentists understand the benefits of dental implant therapy, but the perceived expense of treatment prevents optimal utilization.

Collinearity in linear regression is a serious problem in oral health research

The aim of this article is to encourage good practice in the statistical analysis of dental research data. Our objective is to highlight the statistical problems of collinearity and multicollinearity. These are among the most common statistical pitfalls in oral health research when exploring the relationship between clinical variables using multiple regression analysis. We hope that this article will show why these problems arise and how they can be avoided and overcome. Examples from the periodontal literature will be used to illustrate how collinearity and multicollinearity can seriously distort the model development process as a result of the phenomenon of mathematical coupling. Knowledge of these problems can help to eliminate misleading results and improve any subsequent interpretations. Regression analyses are useful tools in oral health research when their limitations are recognized. However, care is required in planning and it is worthwhile seeking statistical advice when formulating the study's research questions.

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years. II. Combined tooth-implant-supported FPDs

OBJECTIVES

The objective of this systematic review was to assess the 5- and 10-year survival of combined tooth-implant-supported fixed partial dentures (FPDs) and the incidence of biological and technical complications.

METHODS

An electronic MEDLINE search supplemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions.

RESULTS

From a total of 3844 titles and 560 abstracts, 176 articles were selected for full-text analysis, and 13 studies met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in combined tooth-implant-supported FPDs of 90.1% (95 percent confidence interval (95% CI): 82.4-94.5%) after 5 and 82.1% (95% CI: 55.8-93.6%) after 10 years. The survival rate of FPDs was 94.1% (95% CI: 90.2-96.5%) after 5 and 77.8% (95% CI: 66.4-85.7%) after 10 years of function. There was no significant difference in survival of tooth and implant abutments in combined tooth-implant FPDs. After an observation period of 5 years, 3.2% (95% CI: 1.5-7.2%) of the abutment teeth and 3.4% (95% CI: 2.2-5.3%) of the functionally loaded implants were lost. After 10 years, the corresponding proportions were 10.6% (95% CI: 3.5-23.1%) for the abutment teeth and 15.6% (95% CI: 6.5-29.5%) for the implants. After a 5 year observation period, intrusion was detected in 5.2% (95% CI: 2-13.3%) of the abutment teeth. Intrusion of abutment teeth were almost exclusively detected among non-rigid connections.

CONCLUSION

Survival rates of both implants and reconstructions in combined tooth-implant-supported FPDs were lower than those reported for solely implant-supported FPDs (Pjetursson et al. 2004). Hence, planning of prosthetic rehabilitation may preferentially include solely implant-supported FPDs. However, anatomical aspects, patient centered issues and risk assessments of the residual dentition may still justify combined tooth-implant-supported reconstructions. It was evident from the present search that tooth-implant-supported FPDs have not been studied to any great extent and hence, there is a definitive need for more longitudinal studies examining these reconstructions.

Private Practice Results of Dental Implants. Part I: Survival and Evaluation of Risk Factors—Part II: Surgical and Prosthetic Complications

The aim of this study is to present the clinical data from the use of implants that were placed and restored in four independent private dental offices. In part I, the survival rate was calculated and the failure causes were associated with some potential risk factors. In part II, the surgical and prosthetic complications were also recorded and associated both with failures and clinical factors. During 1990-2002 (mean observation 4.6 years), 1692 dental implants were placed and restored in 405 patients in 4 private clinics following the same treatment protocol. The prosthetic restorations included fixed partial dentures, single crowns, and overdentures. The results were statistically analyzed and survival rate probability curves were calculated according to Kaplan-Meier analysis. Part I: Seventy-four implants (4.4%) in a total of 1692 implants failed. The mean of time elapsed before removal of the failed implants was 40 months. The failure rate was higher in the maxilla in patients with metabolic diseases, in D4 bone quality, in smokers, and in patients with insufficient oral hygiene. Part II: Surgical complications happened to 65 implants (3.8%). Prosthetic complications appeared in 152 implants (9%). The overall survival rate (95.6%) in a period of 1 to 12 years is comparable to other studies. The early failures represented a high percentage of failures. Peri-implantitis was the main cause of late failures. The results of this study indicate that the use of implants in private clinics is a safe and predictable method for the treatment of partially or completely edentulous patients, if the proper clinical protocol is followed. The need of a severe recall program must also be emphasized.

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years. I. Implant-supported FPDs

OBJECTIVES

The objective of this systematic review was to assess the 5- and 10-year survival of implant supported fixed partial dentures (FPDs) and to describe the incidence of biological and technical complications.

METHODS

An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions.

RESULTS

The search provided 3844 titles and 560 abstracts. Full-text analysis was performed for 176 articles resulting in 21 studies that met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in implant-supported FPDs of 95.4% (95 percent confidence interval (95% CI): 93.9-96.5%) after 5 and 92.8% (95% CI: 90-94.8%) after 10 years. The survival rate of FPDs supported by implants was 95% (95% CI: 92.2-96.8%) after 5 and 86.7% (95% CI: 82.8-89.8%) after 10 years of function. Only 61.3% (95% CI: 55.3-66.8%) of the patients were free of any complications after 5 years. Peri-implantitis and soft tissue complications occurred in 8.6% (95% CI: 5.1-14.1%) of FPDs after 5 years. Technical complications included implant fractures, connection-related and suprastructure-related complications. The cumulative incidence of implant fractures after 5 years was 0.4% (95% CI: 0.1-1.2%). After 5 years, the cumulative incidence of connection-related complications (screw loosening or fracture) was 7.3% and 14% for suprastructure-related complications (veneer and framework fracture).

CONCLUSION

Despite a high survival of FPDs, biological and technical complications are frequent. This, in turn, means that substantial amounts of chair time have to be accepted by the clinician following the incorporation of implant-supported FPDs. More studies with follow-up times of 10 and more years are needed as only few studies have described the long-term outcomes.

A survey of the use of mandibular implant overdentures in 10 countries

PURPOSE

This preliminary international survey compared provision of implant-retained overdentures to fixed implant-supported prostheses for edentulous mandibles.

MATERIALS AND METHODS

Questionnaires based on a 2001 Swedish study were sent to prosthodontists and specialist clinics in nine additional countries.

RESULTS

Response rate varied from 53% to 100% in 10 national surveys and should allow careful comparison of results. The relationship between implant overdentures and fixed implant-supported prostheses in treatment of edentulous mandibles varied much; in Sweden, the proportion of overdentures was 12%, whereas it was 93% in The Netherlands. In all countries, the most common reason for choice of the overdenture was reduced cost. In all but two countries, the majority of respondents thought that patients with implant overdentures were equally or more satisfied with overdentures as those with fixed implant-supported prostheses.

CONCLUSION

There were great differences among the 10 countries in choice of implant treatment of the edentulous mandible. The relative proportion of mandibular overdentures to fixed prostheses was low in Sweden and Greece and varied from one to two thirds in the other countries, except The Netherlands.

Prosthodontic complications of Spline dental implants

Access to accurate clinical data on the frequency of prosthodontic complications encountered in dental implant restorations can provide dentists with important information for evaluating dental implant systems. The complication of prosthetic screw loosening, for example, has often been ignored or under-reported. Only limited published clinical data exists on the use of the Spline connections for dental implant restorations. This paper reports on an in-vitro investigation of prosthodontic complications encountered with the Spline dental implant system restored by students and residents at The Ohio State University's School of Dentistry. From a comprehensive list of implant patients generated from the University's computer records, an extensive chart review was conducted, and all patients who were treated with Spline dental implants were entered into the study. During a second chart review, data on all prosthodontic complications with Spline implant restorations were gathered on reporting forms then entered into a computer database and subjected to statistical analysis. The results showed that 95.75% of the prostheses were free of any complications. Iatrogenic factors that resulted in screw loosening were identified. Based on the findings of this relatively short-term study ranging from 29 to 59 months of post-restoration clinical follow-up, Spline dental implants provided a stable implant prosthetic connection.

Use of mandibular implant overdentures: treatment policy in prosthodontic specialist clinics in Sweden

The aim was to examine the use of mandibular implant overdentures in Swedish prosthodontic specialist clinics. Questionnaires related to treatment with mandibular implant overdentures during 2001 were sent to the heads of the 30 prosthodontic specialist clinics of the Public Dental Health Service in Sweden. Completed questionnaires were received from 28 (93%). The number of treatments with mandibular implant overdentures varied much among the clinics (0 to 22). Seven clinics had not performed any such treatment, and the median number was 2. The number of fixed implant-supported prostheses was much higher (median value 17, range 4 to 100). The correlation between the number of implant overdentures and fixed implant-supported prostheses in edentulous mandibles was weak (r = 0.33; P = 0.10). The most common anchorage system was ball attachments on two unsplinted implants. The most common reason for the choice of the overdenture treatment was the reduced cost, whereas the patient's main wish to improve denture retention came next. The question whether the demand for implant overdentures had increased during the last few years, was answered with "no" by 19, with "yes" by 5 and with "don't know" by 4 clinics. All but one responded that their attitude to implant overdentures had not changed after the introduction of free pricing in Swedish dentistry. It can be concluded that compared to the rapidly increasing international use of mandibular implant overdentures, this treatment of edentulous patients is rare in Sweden, where fixed implant-supported prostheses still are predominant.

CLINICAL EVALUATION OF OSSEOINTEGRATED IMPLANTS IN TOKYO DENTAL COLLEGE HOSPITAL (THIRD REPORT): LONG TERM OBSERVATION OF FUNCTIONING SURVIVAL RATE OF FIXTURES

The objective of this report was to review 365 cases of Brånemark Implant Bridge including 1,444 fixtures in patients of Tokyo Dental College Chiba Hospital. The term of implantation was divided into several phases; less than 1 year, from 1 year to 3 years, from 3 years to 5 years, from 5 years to 7 years, from 7 years to 10 years, more than 10 years, and the survival rate was calculated for each phase. The removal rate of fixture after connecting the superstructure was 13% in maxillary cases and 2% in mandibular cases. The functioning survival rate in maxillary cases slightly decreased from 91% in less than 1 year to 87% after more than 10 years; however, the functioning survival rate in mandibular cases was about 99% in all periods. The removal rate of fixtures per patient was 23% in maxillary cases and 6% in mandibular ones. The average removal number of fixtures was 1.8 in maxillary cases and 1.2 in mandibular ones. The removal of the fixture occurred most frequently at less than 1 year in maxillary cases, but there was no tendency for a pattern of removal of fixture in mandibular cases.

Debt and practice profiles of beginning dental practitioners

Escalating student debt for dental education has led some to speculate that beginning practitioners may undertake procedures that are beyond their competence in an effort to augment practice income. This hypothesis was tested directLy using a data set containing self-reports of practice profiles across a wide range of procedures and debt for education, practice, and personal purposes. Respondents were 113 individuals who had graduated from a private dental school from 1986 to 1997. Conservative dental practice was measured by comparing frequency of commonly and uncommonly performed procedures in the group as a whole against the profile for each respondent. There was no association between educationaL debt and propensity to engage in unconventional procedures. Older dentists and those who felt more competent at the time of graduation were less conservative. Amount of practice debt was a better predictor of unconventional practice than was educational debt.

Survey of implant experience by prosthodontists in the United States

PURPOSE

The paper presents results of a survey of members of the American College of Prosthodontists (ACP) conducted to determine experiences and practices with dental implants.

MATERIALS AND METHODS

Preliminary survey questions regarding the prosthetic and surgical use of dental implants were developed. The master list of questions was distributed to communities of interest to establish the most pertinent items of interest. The final questionnaire was distributed to all members of the ACP living or practicing in the United States and members engaged in the U.S. armed services. Responses were compiled and analyzed to determine correlation of responses using the chi-squared test for count data (level of significance alpha = 0.05). Fisher's exact test was applied to all significant responses.

RESULTS

Surveys were distributed to 1815 ACP members. A total of 554 (31%) surveys were completed. On the basis of age distribution of survey respondents, it was determined that the respondents were representative of the ACP membership. The majority of the respondents (82%; CI, 79% to 85%) treat patients with implant-supported prostheses, while 12% (CI, 10% to 15%) surgically place implants. Of those not placing implants, 24% reported a desire to place implants, while 43% of all respondents expressed a desire for an ACP-sponsored course in implant placement. Increased age of the prosthodontist correlated negatively with a desire to place implants (p < 0.0001). Dissatisfaction with implant placement by others correlates with willingness to surgically place implants (p < 0.0001).

CONCLUSIONS

Most prosthodontists (82%) use implant-supported prostheses in their practices, but most of the implants are placed by non-prosthodontists. There is general satisfaction with implant placement regardless of the specialty of the practitioner placing the implants. Younger prosthodontists expressed a greater desire to surgically place implants but were not statistically more likely to do so.

Changes in dental conditions during a decade in a middle-aged and older Swedish population

A questionnaire measuring dental conditions was sent to 2708 individuals aged 55 79 years in Orebro County, who about 10 years earlier had been randomly selected for a similar study. The response rate was 68% (1848 individuals). Of those, 1665 had participated also in the 1989 study. The objectives were to study changes in dental conditions having occurred during a decade and to evaluate whether impairment in dental conditions among the participants had resulted in prosthodontic treatments. Only small changes in dental conditions were registered among those who participated both in 1989 and in 1999. Loss of a single tooth was the most frequently reported change. Ten per cent fewer reported that they had all teeth remaining in 1999 compared with conditions in 1989. The number of subjects wearing removable dentures increased only slightly. Although the reported changes in dental conditions were small, there had been a need for prosthodontic treatment in many of the subjects. Ten percent of the subjects reported that they had received FPD treatment during the past 10 years. To conclude, the present study showed that only small changes in dental conditions had occurred among the participants during a decade. Nevertheless, a substantial increase in the prevalence of prosthodontic appliances, especially of fixed restorations, was noted.

An assessment of sensitivity to change of the Oral Health Impact Profile in a clinical trial

Patient-based assessment of oral health outcomes is of growing interest. Measurement of change following clinical intervention is a key property of a health status measure. To date, most of the research on oral health status measurement has focused on construct and discriminant validity of health status measures.

OBJECTIVES

The objective of this study was to assess sensitivity to change of an oral-specific health status measure, the Oral Health Impact Profile (OHIP).

METHODS

Study subjects were in three groups, namely, edentulous/edentate subjects who requested and received complete implant stabilised oral prostheses (IG, n=26), edentulous/edentate subjects who requested implants but received conventional dentures (CDG1, n=22), and edentulous subjects who had new conventional complete dentures (CDG2, n=35). Data were collected pre- and post-operatively using the OHIP and a validated denture satisfaction questionnaire.

RESULTS

All subjects reported similar low levels of denture satisfaction pre-operatively. Denture problems had a more significant impact on oral health-related quality of life (OHRQL) for implant seekers (IG and CDG1 subjects) than subjects seeking conventional dentures (CDG2). Following treatment, significant improvement in satisfaction with oral prostheses and OHRQL was reported by IG and CDG2 subjects; the level of improvement was more moderate for CDG1 subjects. OHIP change scores were correlated with denture satisfaction change scores.

CONCLUSIONS

It was concluded that sensitivity to change of the OHIP was good. This property was not improved by using statement weights.

Accuracy of three corrective techniques for implant bar fabrication

STATEMENT OF THE PROBLEM

Numerous articles emphasize the importance of passivity of implant-prosthetic component interfaces. Nonpassive interfaces can lead to bone loss, abutment fracture, and connecting screw breakage.

PURPOSE

The purpose of this study was to evaluate 3 postcasting techniques for the correction of non-passive fit between a cast bar superstructure and its interface with an implant abutment.

MATERIAL AND METHODS

Thirty implant Hader bars were fabricated based on a metal model composed of two 3.8/4.5 HL PME titanium implant abutments. Initial measurements were collected on the y-axis of the left implant abutment-bar interface by using a M2001ARS toolmaker microscope. Means were calculated from buccal, distal, and lingual measurements on each specimen. Ten specimens were sectioned, indexed, and corrected by casting the same alloy (group 1). Ten specimens were sectioned, indexed, and corrected by soldering (group 2). The last 10 specimens were submitted to 2 cycles of electrical discharge machining on a MedArc M-2 EDM machine (group 3). Postcorrection measurements were collected on the 3 groups. A 1-way ANOVA and a Tukey-Kramer test at a 0.05 significance level were performed on the 3 groups after the corrective techniques.

RESULTS

Initial gap means were 192 microm for group 1, 190 microm for group 2, and 198 microm for group 3. There was a significant difference (P<0.05) in gap means between group 1 (15 microm) and group 2 (72 microm) as well as between group 2 and group 3 (7.5 microm) after each correction technique. No difference was detected between group 1 and group 3.

CONCLUSION

The electrical discharge machining group resulted in the smallest mean gap distance of 7.5 microm, thus meeting the criteria of passive fit (within 10 microm) described in the literature.

In vivo force measurements on maxillary implants supporting a fixed prosthesis or an overdenture: a pilot study

STATEMENT OF PROBLEM

In this preliminary study, an attempt was made to measure in vivo forces simultaneously on 5 maxillary implants with different types of superstructure.

MATERIAL AND METHODS

Force measurements were carried out on 1 test patient with 5 ITI implants in the edentulous maxilla. A screw-retained fixed complete denture and an overdenture were fabricated for comparative measurements of forces. The overdenture could be mounted to 2 different types of bars. The measuring method was used with piezo-electric force transducers that were directly mounted onto the implants. This allowed for simultaneous measurements of forces in 3 dimensions, ie, in axial and transverse directions. Static and functional forces such as maximum biting (clenching), biting on a bite plate, and chewing food were registered. All measurements were repeated in the same way 2 years later.

RESULTS

The registered forces exhibited similar force patterns with both types of superstructure and both types of bars for overdenture connection. The force magnitudes were significantly different for the 3 dimensions (P<.05) with highest forces along the implant axis. On the posterior implants, force magnitudes were significantly higher (P<.05) than on the anterior implants in all 3 dimensions. On the anterior implants, under some test conditions, the transverse force components reached up to 100% of the axial force or even exceeded it during the chewing of food. During maximum biting, no upward force (tensile force) was found on any implant with the fixed complete denture, but upward force was found on one anterior implant with the overdenture. When chewing food, small force magnitudes in upward directions were regularly found with both superstructures. The force patterns between the first and second registrations showed similar trends, and no obvious differences were found.

CONCLUSION

From these results it was concluded that similar patterns of force transmission onto the implants are observed with a fixed complete denture and an overdenture connected to maxillary implants. The bar design did not significantly influence the force pattern.

Measuring the effect of intra-oral implant rehabilitation on health-related quality of life in a randomized controlled clinical trial

The importance of assessing the impact of treatments for chronic conditions on an individual's quality of life has been well-established. In this randomized clinical trial, oral-health-related quality of life, measured with the Oral Health Impact Profile (OHIP), was compared between two groups of edentulous patients. One group (n = 54) received mandibular implant-supported overdentures, and the other group (n = 48) received conventional dentures. Assessments were performed pre-treatment and two months after the prostheses were delivered. The multivariate model showed that implant treatment was significantly associated with lower post-treatment OHIP scores (p = 0.0002), indicating a better quality of life. In addition, pretreatment OHIP scores, treatment allocation, age, sex, and marital status explained 31% of the variation in post-treatment OHIP scores (F = 0.0001). These results suggest that implant treatment provides significant short-term improvement over conventional treatment in oral-health-related quality of life.

Changes in the provision of implant-supported prostheses at the Academic Centre for Dentistry Amsterdam (ACTA) from 1989 to 1995

PURPOSE

Over the last decade, oral implantology has become a major treatment modality to aid the restoration of reduced dentitions. The present study monitored and quantified changes within a 5-year interval (1989-1991 [denoted as 1990*] to 1995) in the provision of different types of implant-supported superstructures and characteristics of recipient patients at the Academic Centre for Dentistry Amsterdam (ACTA).

MATERIALS AND METHODS

All patients who received oral implants in 1990* and in 1995 were selected, and their files (95 and 105, respectively) were consulted. Data of interest were retrieved retrospectively, compared, and statistically analyzed using Chi-squared tests.

RESULTS

A number of statistically significant differences was apparent between these 2 periods. By 1995 there was a threefold increase in both the number of patients and the number of implants placed per year. The patient group of < or = 40 years of age had significantly increased, from 7% to 23%. Also, in 1995 more maxillae were implanted than in 1990* (44% vs 26%). Whereas the majority of implanted patients was edentulous in 1990* (64%), the majority in 1995 was partially edentulous (60%). By 1995, the new technique of guided bone regeneration (GBR) using membranes was evidenced (no GBR in 1990* vs 33% of all patients in 1995 receiving some form of local GBR therapy). With respect to the type of superstructures, there was a strong increase in the number of single-tooth replacements (from 4% to 23%). In the edentulous group, the majority of superstructures in 1990 was fixed prostheses (64%), whereas in 1995 the majority was overdentures (71%).

CONCLUSION

Major changes in oral implantology treatments were noticed between the 1990* and 1995 periods at ACTA. There is a trend toward implanting younger patients for partial implant-supported reconstructions using more regenerative procedures and with a more equal distribution in the maxilla and mandible.

Success of dental implants in elderly people--a literature review

Implant-supported dentures seem particularly appropriate for the predicament of being elderly and becoming edentulous. The aim of this article was to review the literature on success of dental implants in elderly people. The results of two studies suggested that the treatment with implants can be considered safe and predictable for older as well as for younger patients. Three studies found no increased implant failure-rate in patients with a compromised medical status. Four studies revealed high success-rates of dental implants among groups of elderly people. Within the limitations of this review of the literature it can be concluded that old age does not seem to represent a factor of major prognostic significance in treatment with dental implants.