Evaluation of single-tooth restorations on ITI dental implants. A prospective study of 29 patients

Survival of immediate implants replacing traumatised teeth in the anterior maxilla

Aim The provision of implants following traumatic dental injuries can hold many challenges, primarily in higher aesthetic regions. The purpose of this retrospective study was to assess the clinical outcomes of immediate implants placed in fresh extraction sites in the anterior maxilla following dental trauma.Materials and methods In total, 60 patients requiring teeth replacement with dental implants in the anterior maxilla were included in the study. Following a delayed loading protocol, the implants were restored with definitive single crowns or bridges. Implant and prosthetic survival, complications and periodontal health were recorded during follow-up.Results A total of 70 implants were placed in the anterior maxilla with three failures reported, resulting in an implant survival rate of 95.7% over a follow-up period of three years. No additional bone augmentation was undertaken and prosthetic survival recorded was 100%, with favourable periodontal outcomes achieved overall.Conclusion This study showed that implants immediately inserted into fresh extraction sites following dental trauma can constitute a predictable treatment strategy, presenting high implant survival rates over the follow-up period observed. Further well-designed controlled clinical trials are required to evaluate longer-term outcomes for this technique.

Comparison of Osteoimmunological and Microbiological Parameters of Extra Short and Longer Implants Loaded in the Posterior Mandible: A Split Mouth Randomized Clinical Study

OBJECTIVES

This study aimed to evaluate the levels of TNF-α, PGE2, RANKL, RANK, OPG, the markers of periimplant bone loss in peri-implant crevicular fluid obtained around standard and extra short implants. Moreover, the levels of putative oral pathogens were investigated in the submucosal biofilm samples.

MATERIAL AND METHODS

The implants were divided into two groups according to their lengths: standard (≥8 mm) and extra short (4 mm). A total of 60 implants were researched in 30 patients. The probing depth (PD), clinical attachment level (CAL), presence of bleeding on probing (BOP), 3-year survival rate (CSR), and bone loss (BL) were measured.

RESULTS

No statistically significant difference was found in the values of PD, CAL, BOP, CSR, and BL between the groups (P> 0.05). Total amounts of PGE2, TNF-α, RANKL, RANK, OPG, and RANKL/OPG were not statistically significantly different between the groups (P> 0.05). The abundance of F. nucleatum, T. forsythia, P. intermedia, P. gingivalis, S. oralis and T. denticola was compared between the groups and the results were not statistically significant (P> 0.05).

CONCLUSION

The results of this study suggested that PGE2, TNF-α, RANKL, RANK, OPG, and RANKL/OPG in PICF, as well as microbiological parameters in submucosal biofilms, were similar between standard (≥8 mm) and extra short (4 mm) implants. Therefore, the implant length does not seem to influence the bone loss, levels of osteoimmunological and microbiological markers in the peri-implant tissues and survival rates.

3-D tooth movement adjacent to single anterior implants and esthetic outcome. A 14- to 20-year follow-up study

OBJECTIVES

To report three-dimensional (3-D) movement of teeth adjacent to single-implant crowns (SICs) in the anterior maxilla and to relate the findings to patient characteristics and esthetic outcome.

MATERIALS AND METHODS

3-D movements of teeth adjacent to anterior maxillary SICs were measured in 30 patients with original SICs in function after 14-20 years. The movements were related to facial type, lower anterior facial height (LAFH), age at crown delivery, sex, the position of the implant, implant occlusion, cause of tooth loss, follow-up period, orthodontic treatment prior to implant placement, and marginal bone-level changes. The esthetic outcome and quality were assessed using Visual Analog scale (VAS) and California Dental Association (CDA) index.

RESULTS

3-D movement of adjacent teeth between 0 and 2.5 mm was observed at follow-up with incisal and palatal movement being most pronounced. Incisal tooth movement of >1 mm was observed in 30% of the patients and was significantly associated with LAFH ≥70 mm. VAS rating associated poorly between patients and clinicians with scores of >80% in 63% and 20%, respectively. The CDA rating was assessed as satisfactory in 87% of the patients.

CONCLUSIONS

Significantly more extensive infraposition was observed in patients with SICs without occlusion, other causes of tooth loss than trauma, implant in lateral incisor and canine position, and a LAFH of ≥70 mm. Although infraposition occurs, patients are highly satisfied with the esthetics of their implants and the esthetic results are valued as higher by patients than dentists.

A paralleling technique modification to determine the bone crest level around dental implants

The aim of this report is two-fold. First it analyses the precision of a modification of the parallel technique that can be used in those cases with anatomical limitations. Second, it checks the influence of the reference points' definition of objects to be measured by using both the original and the modified radiographic techniques. 2 intraoral radiographs were taken of 28 implants with 2 different methods: a standard paralleling technique and a modified technique that used a smaller film and a silicone spacer to ensure parallelism. Measurements of peri-implant bone levels and implant width were made in triplicate on digitized film radiographs. The results of the peri-implant bone levels were that with the parallel method the mean was 0.44 mm and the precision was 0.43 mm, and with the modified method the mean was 0.73 mm and the precision was 0.66 mm. In addition to the correct localization of the point of reference in this study, the precision with the parallel method was 0.08 mm and with the modified method was 0.13 mm. Although it was greater with the gold standard technique than with the modified technique, precision was very high for both methods and accurate enough for clinical use.

Patient satisfaction after prosthetic rehabilitation of bone-grafted alveolar clefts with nonsubmerged ITI Straumann dental implants loaded at three months

OBJECTIVE

To assess clinical, aesthetic, and quality-of-life parameters of cleft lip and palate patients' implant-supported crowns with ITI Straumann nonsubmerged and loaded after 3 months implants.

PATIENTS, MATERIAL, AND METHODS

In 17 bone-grafted cleft patients, 24 implants were placed nonsubmerged, loaded at 3 months to support crowns in the cleft area, and followed up at 40 months on average (± 22 months). The oral-health-related quality of life was assessed in all patients with the German Oral Health Impact Profile after implant therapy. Aesthetics were judged on photographs by dental professionals, nonprofessionals, and the patients themselves. The Implant Crown Aesthetic Index served as an objective tool.

RESULTS

A total of 23 implants (95.8%) were loaded and in function. Clinical parameters were marginal bone loss of 1.15 ± 2.16 mm, peri-implant probing depth of 2.56 ± 0.66 mm, width of keratinized mucosa of 2.71 ± 1.1 mm, mucosal recession of 0.41 ± 0.8 mm, Periotest value of 0.18 ± 6.5, and German Oral Health Impact Profile summary score of ≤ 2. The best aesthetic outcome was assessed by the patients themselves. Soft tissues were rated worse than were implant-supported crowns.

CONCLUSIONS

Implant-borne prosthetic rehabilitation of bone-grafted clefts with nonsubmerged ITI Straumann implants with 3 months' loading represents a reliable treatment option with high success rates in the long term. Functional aspects are comparable to those of noncleft patients. The oral-health-related quality of life of cleft patients is similar to that of noncleft patients. Aesthetics are restricted but satisfactory to patients and dental professionals. Aesthetics of peri-implant soft tissues should be improved in the future.

Evaluation of aesthetics of implant-supported single-tooth replacements using different bone augmentation procedures: a prospective randomized clinical study

OBJECTIVES

The aim of this study was to evaluate the aesthetics of implant-supported single-tooth replacements using different augmentation procedures in a prospective study with the use of an objective rating index and with a subjective patient questionnaire, and to compare the results with each other.

MATERIAL AND METHODS

Ninety-three patients with a single-tooth gap in the anterior zone of the maxilla were selected for the study. All patients had a local bone defect that needed augmentation before placement of an endosseous implant with sufficient initial stability. Aesthetics of the implant-supported crown and adjacent mucosa was rated by a prosthodontist 1 year after placement of the porcelain crown. Aesthetics was rated using the Implant Crown Aesthetic Index. A subjective appreciation of the final result was assessed with a patient questionnaire.

RESULTS

The Implant Crown Aesthetic Index reveals a mean overall score of 4.8, with an acceptable result in 66% of the cases. Results of the satisfaction questionnaire reveal a mean overall score of 8.5 with an acceptable result in 100% of the cases. There is no correlation between results of the Index and the questionnaire for the overall and the crown score. The patients' opinion and the professionals' opinion about the peri-implant mucosa do show a significant correlation.

CONCLUSIONS

The peri-implant mucosa is rated as less satisfactory than the implant-supported crown by both the dental professional and patients. The dental professional was less satisfied with respect to the total result and results of the crown than the patients.

Optical phenomenon of peri-implant soft tissue. Part I. Spectrophotometric assessment of natural tooth gingiva and peri-implant mucosa

OBJECTIVES

The purpose of this study was to investigate the difference in optical appearance of the soft tissues labial to dental implants and to analyze the effects of titanium implant neck colors transmitted through the marginal mucosa.

MATERIALS AND METHODS

Fourteen patients with 15 Straumann single implant replacements in the maxillary anterior region were recruited. Color measurements of the peri-implant mucosa of test sites and the gingivae of contralateral or adjacent natural teeth as controls were made at the facial aspect of the teeth using a spectrophotometer. The color data (CIELAB color coordinates; L*, a*, b* and C*) in five incremental areas of 1 x 2 mm from the gingival margin toward the apical direction were obtained.

RESULTS

A significant difference existed (P<0.01) between the test site and the control site on the mean L* and b* values in all five incremental areas (area 1-5). In contrast, there was no significant difference in the mean a* values. Discrepancies between color distributions of soft tissues were stronger in areas close to the gingival margin and decreased toward the apical direction. The mean color difference DeltaE between the test site and the control site was 7.7 in area 1 and decreased toward area 5 with a value of 6.5. However, there was no statistical difference in each of the mean values of differences in optical data, DeltaL*, Deltaa* and Deltab*, when five incremental areas of the control and the test sites were compared.

CONCLUSION

It was observed that the color of soft tissue around the titanium implant was significantly different compared with the gingiva of natural teeth. Significantly lower values of CIELAB color coordinates, L* and b* were found in the peri-implant soft tissue.

Long-Term Evaluation of Hollow Screw and Hollow Cylinder Dental Implants: Clinical and Radiographic Results After 10 Years

BACKGROUND

In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and to analyze surgical and prosthetic aftercare.

METHODS

A total of 89 HS and 26 HC implants in 38 edentulous patients were available for complete evaluation. The patients were treated with overdentures stabilized by two or four implants. The follow-up period was 10 years.

RESULTS

The results of the clinical evaluation showed a mean sulcus probing depth of 3.3+/-1.3 mm (range=2 to 10 mm). The mean radiographic bone loss was 2.2+/-2.1 mm (range=0.1 to 12.2 mm). One implant (HS) was removed during the osseointegration period. Three other implants (two HS and one HC) in three patients had to be removed after 10 years. The survival rate of the HS implant (96.6%) was comparable to the HC implant (96.1%). The success rate of the HS implant (93.3%) was slightly more favorable compared to the HC implant (88.5%). The HS and HC implants met the Albrektsson criteria of success.

CONCLUSIONS

HS and HC implants provide a stable base for long-term support of a mandibular overdenture. Furthermore, it is important to monitor peri-implant bone level by taking annual radiographs and measuring probing depth, especially after prolonged service.

Prosthetic treatment of maxillary lateral incisor agenesis with osseointegrated implants: a 24-39-month prospective clinical study

OBJECTIVES

The present study aimed at evaluating the marginal bone resorption and the peri-implant tissue conditions around Narrow-Neck ITI implants in the implant-prosthetic treatment of the agenesis of maxillary lateral incisors.

MATERIAL AND METHODS

Thirty patients affected by monolateral or bilateral agenesis of the maxillary lateral incisors were selected. Thirty-four ITI-SLA Narrow Neck implants were inserted and loaded about 4 months after the surgical procedure. The final restorations were realized using Aureo Galvan Crowns veneered with feldspathic ceramics. The follow-up period ranged from 24 to 39 months. Both marginal bone resorption and soft tissue quality were evaluated. The data were statistically analysed using analysis of variance (ANOVA) for repeated measures, one-way ANOVA and Tukey's post hoc test (P=0.05).

RESULTS

During the 24-39-month follow-up period, no implant showed either pain and sensitivity or mobility. After 39 months of functional loading, a cumulative survival rate of 97.06% and a cumulative success rate of 94.12% were calculated.

CONCLUSIONS

In case of maxillary lateral incisor agenesis, the implant-prosthetic approach has proved to be a reliable and predictable treatment for both re-establishment of function and aesthetics. Satisfactory values of marginal bone resorption over time and optimal conditions of peri-implant tissue around Narrow-Neck ITI implants were found.

A new index for rating aesthetics of implant-supported single crowns and adjacent soft tissues - the Implant Crown Aesthetic Index

OBJECTIVES

The important item of aesthetics is rarely included in evaluation studies. The aim of this study was to develop and validate an index for rating aesthetics of implant-supported single crowns and adjacent soft tissues.

MATERIAL AND METHODS

Nine items were selected, which have an influence on the aesthetic result. The items are based on the anatomic form, colour and surface characteristics of the crown and on the anatomic form, colour and surface characteristics of the peri-implant soft tissues. Two oral-maxillofacial surgeons and two prosthodontists rated 24 implant-supported single-tooth restorations and adjacent soft tissues on a form with the nine items of the rating index. The rating was carried out twice by each of the examiners. Weighted Cohen's kappa was calculated to express the intra- and interobserver agreement.

RESULTS

Intraobserver results indicated that the agreement between the first and second rating of both the prosthodontists was good (both 0.7) and that the agreement of the oral-maxillofacial surgeons was moderate (0.49 and 0.56). The best interobserver agreement was found between the two prosthodontists (0.61, good agreement).

CONCLUSIONS

The Implant Crown Aesthetic Index is an objective tool in rating aesthetics of implant-supported single crowns and adjacent soft tissues. The rating is best be carried out by one prosthodontist to have the highest reliability.

Single-tooth replacement by immediate implant and connective tissue graft: a 1-9-year clinical evaluation

OBJECTIVES

The aim of the present study was to evaluate the long-lasting efficacy of a combined surgical protocol, using immediate implant and subepithelial connective tissue graft for single-tooth replacement. The advantages of this single-center, longitudinal, randomized, blind examiner research were the following: preservation of both keratinized mucosa amount and bone tissue, optimal peri-implant marginal sealing, satisfactory aesthetic results, reduction in treatment time.

MATERIALS AND METHODS

In the time period from 1990 to 1998, 116 patients were consecutively admitted for treatment with a total of 116 solid screw ITI-implants supporting single crowns. Ninety-six patients underwent the proposed combined treatment (test group), while 20 received only single immediate implants (control group). The observation time extended from 1 up to 9 years.

RESULTS

The 9-year cumulative survival rate was 100% for both test and control groups. Comparative statistical analysis of soft and hard tissue peri-implant parameters demonstrated better results in the test group than in the control during every single 3-year analysis and especially in the last observation interval. The test group also showed very good results in terms of aesthetic parameters, which estimated the keratinized mucosa width, the alignment of crown emergence profile and the patient's satisfaction.

CONCLUSION

Single-tooth replacement by immediate solid screw ITI implants in association with connective tissue autograft was demonstrated to be a predictable procedure. Moreover, this treatment can be considered as a sure system to reach an excellent functional and harmonious aesthetic restoration.

Initial Implant Position Determines the Magnitude of Crestal Bone Remodeling

BACKGROUND

The ability to predict the amount of bone remodeling around implants is important for a stable and predictable esthetic result. The purpose of this study was to investigate the amount of radiographic bone remodeling that occurs over time using a one-piece implant system.

METHODS

Twenty-seven patients receiving implants in the maxilla and 15 receiving implants in the mandible were included in the study. All implants were placed with a non-submerged surgical technique with varying locations of the rough-smooth border with respect to the alveolar crest. Clinical exams and radiographs were taken on the day of implant placement, at 6 months, and annually up to 5 years. Linear measurements from digitized radiographs were made from the implant shoulder to the first bone-to-implant contact at all time points.

RESULTS

A significant amount of bone remodeling compared to baseline occurred for all implants at the 6-month follow-up visit (1.10 mm), with the remaining time points showing virtually no change (0.1 mm). A relationship was found between the amount of bone remodeling and the location of the rough-smooth border with respect to the alveolar crest. Those implants with the rough-smooth border surgically placed below the crest had, on average, a greater amount of remodeling at 6 months (average 1.72 mm) than implants with the rough-smooth border placed at or near the crest (average 0.68 mm). In both situations, this remodeling: 1) occurred early (within 6 months), 2) reached a similar level, and 3) remained virtually unchanged up through 60 months (0.05 mm).

CONCLUSIONS

A physiologic dimension appears to exist between the bone and the implant-crown interface around one-piece implants that is established early and maintained over time. These results are significant because they demonstrate in patients that the magnitude of initial bone remodeling around these one-piece dental implants is dependent on the positioning of the rough-smooth border of the implant in an apico-coronal dimension. Furthermore, the dimension, from the crown-implant interface to the first bone-to-implant contact, is consistent with the formation of a biologic width similar to that found around the natural dentition.

Role of mechanical environment and implant design on bone tissue differentiation: current knowledge and future contexts

OBJECTIVES

To evaluate published evidence related to bone reactions to varying loading regimens and the impact of implant design on bone tissue differentiation.

DATA AND SOURCES

The literature was searched for original research articles relating effect of mechanical environment on bone tissue and effects of implant design on bone biomechanics and marginal bone reactions using MEDLINE and manual tracing of references cited in key papers otherwise not elicited.

STUDY SELECTION

Current literature on biomechanics of bone and dental implants as main focus and pertinent to key aspects of the review.

CONCLUSIONS

Implant design influences force transmission characteristics in peri-implant bone, but not the time-dependent marginal bone reactions. Mechanical signals affect bone tissue differentiation. Therefore, it is essential to control biomechanical loads on implants to maintain osseointegration and/or to promote early bone-implant interface healing.

Single implant-supported molar and premolar crowns: a ten-year retrospective clinical report

Evidence of the successful use of osseointegrated dental implants for the restoration of individual teeth has been reported for anterior teeth more frequently than for posterior teeth. Contiguous implants placed in posterior quadrants are often splinted without clear rationale. This clinical report describes the data collected from the charts of patients provided with implant-supported single crowns in posterior quadrants in a prosthodontic practice in southern California. Forty-nine patients with 126 implants restored with molar or premolar crowns were recalled for examination after periods ranging from 6 months to 10 years. The implant failure rate was 4.6%, with complications of abutment screw loosening (7%) and loss of cement bond (22%). Osseointegrated implants in molar and premolar positions may be restored as single crowns.

Performance of Double Acid-Etched Surface External Hex Titanium Implants in Relation to One- and Two-Stage Surgical Procedures

BACKGROUND

The use of external hex titanium implants is widely accepted; however, in the past few years, they have been placed by using not only the traditional two-stage surgical protocol, but also the one-stage surgical protocol. The aim of the present study was to compare the success rates that can be obtained from two-stage surgeries (conventional protocol) and one-stage surgeries when double acid-etched surface external hex titanium implants are used.

METHODS

A total of 654 double acid-etched surface external hex titanium implants were studied in 195 patients (109 females and 86 males) aged 18 to 79 (mean 49.20). These patients were followed-up both clinically and radiographically for 3 years. Among these implants, 338 were inserted by means of two-stage surgery and 316 were placed following the one-stage surgery protocol.

RESULTS

The success rate of the whole sample of double acid-etched surface implants was 99.23%. The results showed a 99.05% success rate for one-stage surgeries and 99.40% rate for two-stage surgeries. Only three of the implants inserted by performing one-stage surgery and two of the implants placed using two-stage surgery failed before they were loaded. No implants were lost after the loading was completed. The bone level at 12 months was 0.58 mm for one-stage-placed implants and 0.54 mm for two-stage-placed implants. At 24 months the bone level was 0.77 mm and 0.68, respectively, and at 36 months 0.89 and 0.83.

CONCLUSION

The similar and high success rates obtained in one- and two-stage surgeries using double acid-etched surface external hex titanium implants demonstrate that it is possible to choose the most convenient surgical procedure for each particular case without increasing the risk of failure.

Evaluation of the mechanical characteristics of the implant-abutment complex of a reduced-diameter morse-taper implant. A nonlinear finite element stress analysis

The purpose of this study was to evaluate the mechanical characteristics of the implant-abutment connection of a reduced-diameter ITI dental implant. A finite element model of a slashed circle 3.3 mm x 10 mm ITI solid-screw implant and a 6 degrees solid abutment 4 mm in height was constructed, and the implant-abutment complex was embedded vertically in the center of a slashed circle 1.5 cm x 1.5 cm acrylic cylinder. Static vertical and oblique loads of 300 N were applied in separate load cases. The contact area was defined between the implant-abutment connection and nonlinear finite element stress analysis was performed. The magnitude and distribution of Von Mises stresses and displacement characteristics were evaluated. In vertical loading, Von Mises stresses concentrated around the implant-abutment connection at the stem of the screw and around the implant collar. Oblique loading resulted in a 2-fold increase in stresses at the implant collar, which was close to the yield strength of titanium. Displacement values under both loading conditions were negligible. We conclude that, in a reduced-diameter ITI dental implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. The neck of this implant is a potential zone for fracture when subjected to high bending forces. The reduced-diameter ITI dental implant might benefit from reinforcement of this region.

Single-tooth implant treatment in the anterior region of the maxilla for treatment of tooth loss after trauma: a retrospective clinical and interview study

The aim of this study was to evaluate the results of single-tooth implant treatment in patients where teeth have been lost as a result of trauma. Also, the patients' and professionals' opinions regarding the final outcome of treatment were assessed. Thirty-four patients with 42 lost teeth were evaluated by clinical and radiographic examinations and interviews 2-5 years after treatment. A professional who had not taken part in the treatment evaluated the implant crowns. Central maxillary incisors were the most frequently lost and replaced teeth after trauma (75%) followed by lateral incisors (21%). In patients with incomplete growth, implant treatment was generally postponed until completion of growth. Lack of space was treated by presurgical orthodontics (7%) or by selecting an implant with a reduced diameter (5%). Deficiency of bone was seen in 17% and was treated by bone grafting or local augmentation prior to implant surgery. Patients who had lost two or more teeth after trauma were all subjected to bone grafting. Preservation of roots in the alveolar process seemed to maintain the bone volume enabling better conditions for later implant placement. Forty-one implants (97.6%) were integrated successfully. Complications were few and of minor importance (9.5% before and 12% after cementation of crowns) and could all be managed. No or minimal bone loss was seen. In general, the patients felt that they received good care and that they were well informed about their treatment. Some patients reported that the local anesthesia procedure was not pain-free, but 71% of the patients experienced the treatment as pain-free. For each of the variables (color, shape, height, and size of the crowns), the highest degree of satisfaction was noted in 93-98% of the patients and 91-95% of the single evaluating professional. Given that the patients have finished growth and a careful treatment planning and timing are performed, the functional and esthetical outcome of single-tooth implant treatment today is excellent and can be recommended for replacing tooth losses after trauma in the anterior region of the maxilla.

Patient satisfaction and quality of single-tooth restorations

This retrospective study focuses on patient opinion and professionally assessed quality of single-tooth restorations of Brånemark fixtures. Patients were treated by periodontists for fixture installation and/or abutment connection and by referring general practitioners for prosthetic rehabilitation. Seventy-eight consecutively treated patients were sent a questionnaire regarding aesthetics, phonetics and overall satisfaction. Forty-eight patients (52 fixtures) returned the questionnaire. Forty were able to attend a clinical examination by an independent examiner. The quality of 43 single implant crowns was evaluated according to the modified guidelines for assessment of quality and professional performance used for evaluation of design, fit, occlusion/articulation and aesthetics. Bone to implant level was assessed radiographically. Patients were very positive about aesthetics, phonetics, eating comfort and overall satisfaction. Nevertheless, 6/40 patients would not undergo the same treatment again, yet all of them would recommend it to others. The professionally rated quality of the crowns was perfect in 17 and acceptable in 25 cases. One crown needed modification to prevent future complications. Two crowns had already been replaced as a result of porcelain fracture; one restoration showed abrasion and one was damaged. With a mean loading time of 33 months (range: 3-89 months), none of the patients returning the questionnaire had encountered fixture loss. All except five fixtures showed bone remodelling at or above the first implant thread. It is concluded that single Brånemark fixtures installed by periodontists and restored by general practitioners are of an acceptable clinical quality to satisfy the patient.

Long-Term Changes in Soft Tissue Height on the Facial Surface of Dental Implants

The success of osseous healing around dental implants has allowed for an increased emphasis on soft tissue healing and esthetic results. However, there is limited information profiling the long-term healing of the soft tissues following prosthesis placement. The purpose of this study was to assess the long-term changes in the position of the facial soft tissue margins following restoration of a one-stage implant system. One hundred and six one-stage ITI implants were evaluated in 39 patients. Implants were placed in maxillary and mandibular anterior regions. Clinical assessment of the soft tissues on the midfacial aspect of the implants was performed over a 2-year period, at 3 and 6 month intervals, following placement of the final restoration. A total of 63 implants were placed as multiple units in the mandible, 23 as single units in the maxilla, and 20 as multiple units in the maxilla. There were no implant failures over this time period. Overall, on the facial aspect of 61% of the 106 implants there was 1 mm or more of soft tissue recession, whereas 19% of the implants showed 1 mm or more of gain in soft tissue height. There was a significantly (P < 0.01) greater number of implants showing a gain in soft tissue levels in the mandibular implants compared with the maxillary implants. Of the 39 patients assessed, 24 showed a loss and five showed a gain of 1 mm or more of the soft tissue levels around the implants. Overall, there was a significant decrease in the mean levels of tissue height of 0.6 mm within the first 6 months, with relatively little change afterward. However, in evaluating only patients showing a loss in tissue height around one or more implants, the mean loss in tissue height was 1.6 mm after 24 months. These results suggest that the potential for significant changes in soft tissue levels after completion of restorative therapy need to be considered for implant therapy in esthetic areas.

The single-tooth implant: a viable alternative for single-tooth replacement

BACKGROUND

The use of dental implants for single-tooth replacement cases introduces a challenge to the performance of these restorations. Clinical data suggest that single-tooth implant restorations do not benefit from lateral support from the surrounding dentition as do bridged implants, and that these restorations are subjected to greater masticatory forces. Therefore, single-tooth implants are exposed to an increased risk of failure. This prospective clinical trial was designed to evaluate the cumulative success rate of dual acid-etched single-tooth replacement implants in two clinical centers.

METHODS

The study protocol included 59 patients between 19 and 73 years. Implants were evaluated for mobility, infection, and crestal bone loss from 30.9 to 60 months.

RESULTS

Seventy-one (71) implants were placed in 59 patients, 20 male and 39 female. Forty-seven (47) were placed in the maxilla and 24 in the mandible. The percentages of anterior and posterior implants were 45.1% and 54.9%, respectively. A total of 13 (18.4%) implants were placed in soft, poor quality (Type IV) bone. Beginning 1 month post-implant placement, cases were followed for 30.9 to 60 months with a mean follow-up of 45.9 months. One implant failed (peri-implant infection) yielding an overall success rate of 98.6%.

CONCLUSIONS

This success rate for single-tooth replacement dual acid-etched implants compares favorably with bridged implants and with success rates of other single-tooth implant studies. Dual acid-etched implants performed well even under conditions of poor quality bone, where concomitant bone augmentation was performed, and when used for immediate replacement of extracted teeth.

Effect of splinting and interproximal contact tightness on load transfer by implant restorations

STATEMENT OF PROBLEM

To circumvent the difficulty of achieving a passive framework fit, some authors have suggested that multiple adjacent implants be restored individually. This protocol requires that each unit be able to withstand mastication forces. Non-splinted restorations have numerous interproximal contacts that require adjustments prior to placement, with an unknown outcome relative to load transfer.

PURPOSE

This in vitro simulation study examined the effect of splinting and interproximal contact tightness on passivity of fit and the load transfer characteristics of implant restorations.

MATERIAL AND METHODS

A photoelastic model of a human partially edentulous left mandible with 3 screw-type implants (3.75 x 10 mm) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 custom-milled titanium abutments. After the units were cemented, 5 levels of interproximal contact tightness were evaluated: open, ideal (8 microm shim stock drags without tearing), light (ideal +10 microm), medium (ideal + 50 microm), and heavy (ideal + 90 microm). For splinted restorations, five 3-unit fixed partial dentures were fabricated, internally adjusted with silicone disclosing material, and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions (6.8 kg) were analyzed with a polariscope.

RESULTS

In the simulated alveolar structures, non-splinted restorations with heavier interproximal contacts were associated with increased tensile stresses between implants; occlusal loads tended to concentrate around the specific loaded implant. Splinted restorations shared the occlusal loads and distributed the stresses more evenly between the implants when force was applied. The load-sharing effect was most evident on the center implant but also was seen on the terminal abutments of the splinted restorations.

CONCLUSION

The results of this in vitro study suggest that excessive contact tightness between individual crowns can lead to a non-passive situation. In this experiment, splinted restorations exhibited better load sharing than non-splinted restorations.

Long-term clinical effectiveness of oral implants in the treatment of partial edentulism. Seven-year life table analysis of a prospective study with ITI dental implants system used for single-tooth restorations

One hundred and eight-seven ITI implants were prospectively followed from November 1992 to July 2000, in order to evaluate the clinical efficiency and the long-term prognosis in 109 partially edentulous patients (69 women and 40 men; average age 41.3 years). Of these 187 implants, 69.5% were placed in the mandible and 30.5% in the maxilla. After a healing period that ranged from three to six months, the osseointegrated implants (n = 184) were restored with single crowns. Three implants were extracted prior to loading the fixture and were considered early failures. Each implant was reassessed on a yearly basis, both clinically and radiographically. The results of the investigation, which were evaluated according to predefined success criteria, were reviewed in accordance with a life table method. During the follow-up, six cases were deemed to be late failures. In each of these cases, a suppurative infection of the peri-implant tissue was diagnosed: in one implant, the infection could not be eradicated and the implant was removed. When 11 drop-outs were included in the analysis, the cumulative survival and success rates for the whole sample group were 96.77% and 93.6%, respectively. When only prosthetically loaded implants were considered, the results increased to 99.35% for the cumulative survival rate and 96.18% for the cumulative success rate. The analysis on disaggregated data showed better results for maxillary restorations (survival rate 100%) in comparison to mandible restorations (survival rate 95.11%). It was concluded that, under standard anatomic conditions (bone site height > 8 mm, thickness > 6 mm), prosthetic restoration of partially edentulous patients with the ITI system can be described as a reliable and efficient therapy in the long term.

A meta-analytic, quantitative assessment of osseointegration establishment and evolution of submerged and non-submerged endosseous titanium oral implants

Two implant placement methods are used in oral implantology: submerged (S, two-stage surgical procedure) and non-submerged (NS, one-stage surgery). However, a quantitative assessment of their influence on implant osseointegration, summarising the whole present experience, is not directly possible, owing to the lack of normalisation of the published results. To overcome this difficulty, selection criteria have been applied to the latter in a process of a meta-analysis of specialised literature, in order to authorise a pooled treatment with an adequate statistical method. Survival life tables are established (up to 15 and 10 years respectively for S and NS implants placed in normal situations) for extended samples (13049 S and 5515 NS implants). Early (before loading) failure rates and 95% confidence level ranges of cumulative implant survival rates are shown. For both categories, the quality of the placement stage remains critical to ensure optimal osseointegration behaviour. Both categories match current survival requirements, but with a quite different behaviour over time. NS implants, while osseointegrating better initially, are subject to causes of osseointegration loss, which persist over a longer period of time. Implant design characteristics (including the type of surface) seem to be more relevant than the placement procedure for the implant's behaviour. This is in agreement with recent histological and preliminary clinical results, and should be confirmed by further studies.

Brånemark System and ITI Dental Implant System for treatment of mandibular edentulism. A comparative randomized study: 3-year follow-up

In a randomized prospective study, two implant systems were compared in forty consecutive patients treated for mandibular edentulism. The patients were randomly allotted for treatment by the Brånemark two-stage (submerged) system (BRS), or the ITI(R) one-stage (non-submerged) system. In all, 102 Brånemark selftapping implants and 106 ITI hollow screw implants were installed and all patients were treated with full bridges. Biological and prosthodontic parameters, complications, success rates, clinical efficacy, patient satisfaction and resource requirements were evaluated. No differences were found in plaque accumulation, bleeding or complications during the follow-up period. The BRS group showed deeper periimplant sulcus, less attached mucosa, larger bridge-mucosa distance and higher Periotest values. Prosthetic complications were not related to the configuration of the implant systems. After 3 years, the cumulative success rates were 97.9% and 96.8% for the Brånemark and ITI systems, respectively (difference not statistically significant). One implant in the BRS group had failed to osseointegrate at the time of abutment connection, and another was lost after 2 years due to progressive breakdown of bone. In the ITI group, three implants showed progressive bone loss after 1-3 years associated with periimplant infection. All 40 bridges were intact and remained stable throughout the study. There was general patient satisfaction, but about half the Brånemark patients reported difficulty in coping with the surgical procedures. Treatment time was similar for the two systems. It is concluded that both systems meet the current requirements for dental implant systems in the treatment of mandibular edentulism.

Nonsubmerged implants in the treatment of the edentulous lower jaw: a 5-year prospective longitudinal study of ITI hollow screws

BACKGROUND

Although most implant systems have been designed for a two-stage surgical technique, a one-stage surgical technique has always been advocated for the ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland). A new generation of ITI implants was presented in 1988 and included a hollow cylinder, a hollow screw, and a solid screw.

PURPOSE

The goal of this study was to evaluate the one-stage surgical technique in connection with the ITI hollow screw in a longitudinal study over 5 years.

MATERIALS AND METHODS

Forty-six patients with edentulous lower jaws were supplied with ITI hollow-screw implants. Patients who requested an overdenture (n = 18) had four implants inserted; those who requested a fixed bridge (n = 28) had five to six implants. The patients have been followed annually for 5 years. There was a dropout of three patients (6.5%); one patient did not want to cooperate, one moved from the area, and one was deceased. The clinical examinations included bridge removal for evaluation of the individual implant stability in connection with the 1-, 3-, and 5-year examinations. Radiographic examinations were performed with intraoral radiographs and the long-cone technique.

RESULTS

The survival rate after 5 years was 95.7%. The success rate (in which implants undergoing treatment of peri-implantitis were not counted as successes) was 91.4%. The mean marginal bone loss between the baseline and the 1-year examination was 0.1 mm and between the 1- and 5-year examinations was 0.1 mm. These changes in marginal bone level were not significant.

CONCLUSIONS

The success rate of ITI hollow-screw implants in the edentulous mandible was 91.4% after a 5-year observation period. There was no significant change in mean bone level between the loading of the implants and the 5-year examination. Peri-implantitis was diagnosed in three patients with poor oral hygiene, and it affected six implants. Five of these failed in spite of treatment.

Clinical evaluation and prosthetic complications of single tooth replacements by non-submerged implants

The aim of the present study was to evaluate single tooth replacements by non-submerged implants. In the time period from 1990 to 1998, 72 patients were consecutively admitted for treatment with a total of 109 solid screw ITI-implants supporting single crowns. All crowns were ceramic to metal fused with a ceramic occlusal surface and mounted to the octa-abutment. The mean observation time was 4.3 years, ranging from >1 to 9 years. The implants were monitored regularly by periimplant parameters. Periapical radiographs using the parallel technique were taken after the healing period and in 1999 for comparative measurements. No implant was lost during the healing phase, while 3 failures occurred after a loaded period of 2.5 and >5 years, respectively. The 5-year cumulative survival rate was 99.1%. In the course of the study, only 2 implants exhibited marginal inflammation that required treatment. The radiographically measured distance (DIB) from the implant shoulder to the first implant-bone contact was significantly increased in 1999 and different between the two readings. However, this difference in DIB was not significant between implants with a short (1 year) and long (>5 years) observation period. It was concluded that changes in the crestal bone level occur mostly in the first postsurgical year. Prosthetic complications were rare, mostly encountered in the first year after loading and often limited to re-tightening of the occlusal screw.

Glass fiber-reinforced abutments for dental implants. A pilot study

Titanium abutments in dental implants shine through all-ceramic crowns and therefore limit excellent esthetic results. Prototypes of tooth-colored fiber-reinforced abutments were investigated to avoid the shining-through effect. In vitro, the fracture strength was determined after thermal cycling and mechanical loading of all-ceramic single crowns and four-unit bridges made of a fiber-reinforced composite. The suprastructures were adhesively fixed onto fiber-reinforced implant abutments and compared with those fixed on standard titanium abutments. The median of the fracture strength of the titanium-supported all-ceramic crowns was significantly higher than the median of crowns fixed onto the prototypes. But this value was still more than twice as high as the maximum loading force under oral conditions. No statistical difference was found between four-unit bridges made by fiber-reinforced composite inserted onto titanium abutments and those inserted onto fiber-reinforced abutments. Fiber-reinforced abutment prototypes for dental implants avoided the shining-through effect associated with metal abutments. Their load-bearing capacity after in vitro stress simulation was higher than the maximum oral loading force. With some improvements, the fiber-reinforced implant abutments are therefore a promising alternative to titanium abutments.

Osseointegrated Implant for Single-Tooth Replacement: A Retrospective Multicenter Study on Routine Use in Private Practice

BACKGROUND

Implant restorations first started with total edentulism. Later, the scientific community gave its approval for restorations in partial edentulism, and only recently some studies confirmed the validity of the treatment for single-tooth replacement.

PURPOSE

The purpose of the study was to evaluate implant survival and prosthesis stability of Brånemark implants (titanium screws) when used routinely for single-tooth replacement in all regions.

MATERIALS AND METHODS

Two hundred and fourteen patients received 252 implants for single-tooth replacement over a period of 8 years at five private clinics in Italy. The patients were treated in accordance with the protocol for Brånemark implants, and the data gathered have been analyzed according to established evaluation methods.

RESULTS

During the observation period, 10 failures were recorded and 229 restorations were carried out. After the first year of loading, the total cumulative survival rate (CSR) was 96%, which then remained stable over the study time. The most frequent complication was loosening of the abutment screws (n = 22), amounting to 35% of all of the complications. This problem was related mainly to earlier types of abutments, whereas the more recent design, CeraOne abutment, showed a low frequency of screw loosening.

CONCLUSIONS

The high survival rate, which is similar to that presented for prospective multicenter studies for single-tooth restorations with Brånemark implants, led to the conclusion that the use of this treatment modality is a reliable treatment for routine use in all oral regions.