A 5-year prospective study of Astra single tooth implants

Three interfaces of the dental implant system and their clinical effects on hard and soft tissues

Anatomically, the human tooth has structures both embedded within and forming part of the exterior surface of the human body. When a tooth is lost, it is often replaced by a dental implant, to facilitate the chewing of food and for esthetic purposes. For successful substitution of the lost tooth, hard tissue should be integrated into the implant surface. The microtopography and chemistry of the implant surface have been explored with the aim of enhancing osseointegration. Additionally, clinical implant success is dependent on ensuring that a barrier, comprising strong gingival attachment to an abutment, does not allow the infiltration of oral bacteria into the bone-integrated surface. Epithelial and connective tissue cells respond to the abutment surface, depending on its surface characteristics and the materials from which it is made. In particular, the biomechanics of the implant-abutment connection structure (i.e., the biomechanics of the interface between implant and abutment surfaces, and the screw mechanics of the implant-abutment assembly) are critical for both the soft tissue seal and hard tissue integration. Herein, we discuss the clinical importance of these three interfaces: bone-implant, gingiva-abutment, and implant-abutment.

Cemented versus screw-retained zirconia-based single implant restorations: 5-year results of a randomized controlled clinical trial

Objectives

To compare cemented and screw‐retained one‐piece zirconia‐based restorations in terms of clinical, radiographic, and technical outcomes 5 years after insertion.

Materials and methods

Thirty‐four patients with single‐tooth implants were randomly restored with either a cemented lithium disilicate crown on a one‐piece customized zirconia abutment (CEM, 17 patients) or a screw‐retained crown based on a directly veneered one‐piece customized zirconia abutment (SCREW, 16 patients). All patients were recalled for a baseline examination (7–10 days after crown insertion) and then annually up to 5 years. The following outcomes were assessed: marginal bone level (changes), technical, and clinical (bleeding on probing, plaque control record, probing depth, and keratinized tissue) parameters. The Mann–Whitney U‐test was used to assess differences between the two groups.

Results

At 5 years, 26 patients (13 in each group) were re‐examined. The survival rates on the implant and restorative levels were 100% and 82.4% (equally for both groups), respectively. At 5 years, the median marginal bone level was located at −0.15 mm (IQR: −0.89 mm; 0.27 mm) (CEM) and −0.26 mm (IQR: −0.38 mm; 0.01 mm) (SCREW) below the implant shoulder (intergroup p = .9598). The median changes between baseline and the 5‐year follow‐up amounted to −0.23 mm (CEM; intragroup p = .0002) and −0.15 mm (SCREW; intragroup p = .1465) (intergroup p = .1690). The overall technical complication rate at 5 years was 15.4% (CEM) and 15.4% (SCREW) (intergroup p = 1.00). Clinical parameters remained stable over time (baseline to 5 years).

Conclusions

At 5 years, screw‐retained and cemented restorations rendered largely the same clinical, technical, and radiographic outcomes. Technical complications were frequent in both groups.

Evaluation of Bone Regeneration around Implants with and Without Flap Elevation

Background:

The aim of this study is to clinically evaluate and compare the clinical success and the relative bone healing of the implants which are placed using a flapless procedure and compare it to those placed by the conventional flap technique.

Materials and Methods:

This study was conducted with ten patients that were randomly divided into two groups. Group A included patients with immediately placed implants after extraction with flap elevation. Group B included patients with immediately placed implants after extraction without any flap elevation. The clinical parameters recorded were Plaque index, Modified Gingival Index, Early Wound Healing Index, Buser's criteria, Distance between implant shoulder and the crestal bone (DIB), and Radiographic Examination in a standardized manner to evaluate changes for the DIB values.

Results:

There was an improvement in Plaque Score from baseline to 1 month and baseline to abutment placement (6 months), which was statistically significant, but the plaque score from 3 months to abutment placement (6 months) was statistically nonsignificant in both the group. There was an increase in modified gingival score from baseline to 3 months, baseline to abutment placement (6 months), and 3 months to abutment placement (6 months), which was statistically significant in both the groups. The DIB scores in Group A recorded at baseline to 6 months were 2.80 ± 0.57 and 1.90 ± 0.42, respectively, showing a mean difference of −0.90 and P = 0.001 in comparison. Whereas, the DIB scores in Group B at baseline to 6 months were 3.20 ± 0.57 and 2.50 ± 0.50, respectively, showing a mean difference of −0.70 and P = 0.001 in comparison. The DIC scores in Group A at baseline to 6 months were 1.60 ± 0.54 and 0.00 ± 0.00, respectively, showing a mean difference of −1.60 and P = 0.003 in comparison, Whereas the DIC scores in Group B at baseline to 6 months were 1.40 ± 0.54 and 0.00 ± 0.00, respectively, showing a mean difference of −1.40 and P = 0.005 in comparison.

Conclusion:

Implants placed in fresh extraction sockets with and without mucoperiosteal flap elevation can be successfully done with augmentation procedures. Short-term survival rates and clinical outcomes of both groups were similar and appeared to be predictable treatment modalities.

The effect of implant-abutment connections on peri-implant bone levels around single implants in the aesthetic zone: A systematic review and a meta-analysis

Objective

To systematically review literature about the effect of different implant‐abutment interface designs on peri‐implant bone level changes, implant loss and mid‐buccal mucosa changes around single implants in the anterior maxilla. Reviewing three connection configurations: Platform switched conical (PS‐conical); Platform switched parallel (PS‐parallel); Platform matched parallel (PM‐parallel).

Methods

A detailed search was carried out in Pubmed, EMBASE, Cochrane, Scopus, Open Gray and African journals Online (until December 1, 2020) and was restricted to clinical prospective studies of at least 1 year and with at least 10 human participants. A meta regression analysis was carried out primarily on the pooled peri‐implant bone level changes followed by implant loss and mid‐buccal mucosa level change. Risk of bias was assessed with RoB 2.0 and ROBINS‐I. The manuscript complied with the PRISMA guidelines and was registered in the PROSPERO database (ID: 225092).

Results

A total of 5513 hits gave 44 eligible articles for the analyses. Bone level change did not differ significantly between the two platform switched connections; their bone loss scores were significantly lower than PM‐connection. The PS‐conical connections have significantly lower implant losses than the PM connection. Mid‐buccal mucosa level change was comparable between the three connection configurations. Moderate to high risk of bias was detected in the included studies.

Conclusions

The performance of PS‐conical and PS‐parallel connection configurations both favored bone loss scores compared to the PM‐parallel connection configuration. All three demonstrated mid‐buccal mucosa changes that were small and did not differ significantly amongst the groups.

Axial Displacements and Removal Torque Changes of Five Different Implant-Abutment Connections under Static Vertical Loading

The aim of this study was to examine the settling of abutments into implants and the removal torque value under static loading. Five different implant-abutment connections were selected (Ext: external butt joint + two-piece abutment; Int-H2: internal hexagon + two-piece abutment; Int-H1: internal hexagon + one-piece abutment; Int-O2: internal octagon + two-piece abutment; Int-O1: internal octagon + one-piece abutment). Ten implant-abutment assemblies were loaded vertically downward with a 700 N load cell at a displacement rate of 1 mm/min in a universal testing machine. The settling of the abutment was obtained from the change in the total length of the entire implant-abutment unit before and after loading using an electronic digital micrometer. The post-loading removal torque value was compared to the initial torque value with a digital torque gauge. The settling values and removal torque values after 700 N static loading were in the following order, respectively: Ext < Int-H1, Int-H2 < Int-O2 < Int-O1 and Int-O2 < Int-H2 < Ext < Int-H1, Int-O1 (α = 0.05). After 700 N vertical static loading, the removal torque values were statistically different from the initial values, and the post-loading values increased in the Int-O1 group and Int-H1 group (α = 0.05) and decreased in the Ext group, Int-H2 group, and Int-O2 group (α = 0.05). On the basis of the results of this study, it should be taken into consideration that a loss of the preload due to the settling effect can lead to screw loosening during a clinical procedure in the molar region where masticatory force is relatively greater.

Biological Responses to the Transitional Area of Dental Implants: Material- and Structure-Dependent Responses of Peri-Implant Tissue to Abutments

The stability of peri-implant tissue is essential for the long-term success of dental implants. Although various types of implant connections are used, little is known about the effects of the physical mechanisms of dental implants on the stability of peri-implant tissue. This review summarizes the relevant literature to establish guidelines regarding the effects of connection type between abutments and implants in soft and hard tissues. Soft tissue seals can affect soft tissue around implants. In external connections, micromobility between the abutment and the hex component of the implant, resulting from machining tolerance, can destroy the soft tissue seal, potentially leading to microbial invasion. Internal friction connection implants induce strain on the surrounding bone via implant wall expansion that translates into masticatory force. This strain is advantageous because it increases the amount and quality of peri-implant bone. The comparison of internal and external connections, the two most commonly used connection types, reveals that internal friction has a positive influence on both soft and hard tissues.

Esthetic aspects in implant-prosthetic rehabilitation

The esthetic component is critical for the successful outcome and patients’ satisfaction regarding the implant-prosthetic therapy. The esthetic outcome success depends mostly on the optimization of the algorithms specific to the pro-implant and implant stage as well as to the designing and technological execution of the future prosthetic restoration. A proper planning of optimal facial esthetics must involve a multidisciplinary approach with inclusion of periodontists, orthodontists, oral surgeons and implantology specialists. The dental practitioner must consider various factors that influence the esthetic outcome (tooth position, root position of the adjacent teeth, biotype of the periodontium, tooth shape, smile line, implant site anatomy, implant positioning). Also, some factors (anatomical limits of the implant site, periodontal status, occlusal parameters), which can alter the final esthetic result, must be assessed prior to planning the esthetic parameters of the future prosthetic restoration. The esthetic outcome can be improved by using new digital technologies based on software applications for assessment of clinical and biological indices of the prosthetic field, virtual planning of implants positioning and design projection of future prosthetic restoration.

Performance of bone-level implants with conical connections in the anterior maxilla: A 5-year prospective cohort study

OBJECTIVES

To assess clinical, radiographic and aesthetic outcomes, and satisfaction of patients treated with single implant restorations in the maxillary aesthetic region 5 years after final restoration.

MATERIAL AND METHODS

Sixty patients (29 male/31 female, mean age 37 years) with a missing anterior tooth in the maxilla (39 central incisors/10 lateral incisors/5 cuspids/6 first premolars) received a bone-level implant with conical connection. In 29 patients, a bone augmentation procedure was necessary before implant placement (autogenous bone grafts mixed with spongiosa granules). All implants (12 with 3.3 mm diameter/ 48 with 4.1 mm diameter) were loaded after 3 months of submerged healing. The restoration consisted of an individually designed full-zirconia abutment veneered with porcelain. Follow-up with clinical and radiographic assessment was conducted until 60 months after the final restoration. Aesthetic outcome of the restoration was determined with the Pink Esthetic Score-White Esthetic Score (PES-WES). Patient satisfaction was assessed with a VAS scale and satisfaction questionnaire.

RESULTS

Fifty patients completed the 5-year follow-up. Implant survival was 100%, restoration survival 98%. Mean bone-level change was -0.13 ± 0.66 mm with a median (IQR) pocket probing depth of 2.75 [2.25; 3.25]. The mean PES and WES scores were 6.6 ± 1.7 and 7.8 ± 1.5, respectively. Patient satisfaction was high (92.1 ± 7.8 on 100 mm VAS scale). There were no differences between patients with or without a bone augmentation procedure.

CONCLUSION

Bone-level implants with a conical connection are a reliable treatment option in single-tooth replacements in the maxillary aesthetic zone.

Evaluation of the influence of implant placement timing on the esthetic outcomes of single tooth implant treatment in the anterior maxilla: A retrospective study

OBJECTIVES

The purpose of this retrospective study was to investigate the influence of implant placement timing on the esthetic outcomes for single implants in the anterior maxilla.

MATERIALS AND METHODS

One hundred and ten patients (48 males; 62 females) who received a single-tooth implant after extraction either immediately (Type 1); after 4-8 weeks (Type 2); after 8-16 weeks (Type 3); or more than 16 weeks (Type 4) were evaluated in terms of esthetic outcomes after a mean post-placement interval of 26.3 months (range 12-116). Esthetic outcomes were measured using the Pink and White Esthetic Score (PES; WES). Stepwise regression analysis was performed to analyze the effect of timing of placement, as well as patient demographics and other clinical parameters on the esthetic outcomes.

RESULTS

No statistically significantly differences in PES were found between the various treatment modalities with Type 1 implants (n = 33) scoring 10.58 ± 1.65 (median: 11), followed by 10.36 ± 2.09 (median: 10.5), 9.68 ± 2.43 (median: 10), and 9.63 ± 2.21 (median: 10) for Type 2 (n = 14), Type 3 (n = 19), and Type 4 (n = 44), respectively. For immediate implants, a trend towards better esthetic outcomes was observed when implant placement was done flaplessly in cases with intact buccal bone (Type 1A, median PES 11) as compared to cases with partial/complete missing buccal plates where a flap was raised (Type 1B, median PES 10). Overall, the only parameter that influenced esthetic outcomes (as measured by PES) was gender, with females having significantly superior results. The median WES was 8 and 96% of the crowns were deemed esthetically acceptable, with crowns placed by specialist prosthodontists yielding higher scores than those placed by general practitioners.

CONCLUSIONS

Single tooth implants in the anterior maxilla showed satisfactory outcomes when measured with objective esthetic criteria. Timing of implant placement did not significantly influence the esthetic outcomes, although a trend towards better outcomes was seen with immediate implant placement as observed by higher median PES values.

CLINICAL SIGNIFICANCE

Single tooth implant placement in the anterior maxilla is a predictable treatment modality for achieving acceptable esthetic outcomes regardless of the timing of placement.

Irregular Implant Design Decreases Periimplant Stress and Strain Under Oblique Loading

OBJECTIVES

To investigate whether a different implant geometry with the same potential contact surface area (PCSA) affects the principal stress and strains in bone.

MATERIAL AND METHODS

Three-dimensional finite-element models were created with a single endosseous implant embedded in bone. The irregular (IR) dental root-analog implant and regular (R) cylindrical implant with the same PCSA 350 mm were modeled, keeping the size of the thinnest implant wall 0.8 mm, and the thinnest bone wall 1 mm. The regular or irregular abutments were either 4.5 mm lower than the platform of the implants or 5 mm higher than the platform of the implants, both with the taper 1.44°. A 100 N vertical or 100 N vertical/50 N horizontal occlusal loading was applied. The biomechanical behaviors of periimplant bone were recorded.

RESULTS

The IR implant design experienced lower periimplant stress and strain under oblique loading than that of R implant design. In the IR implant design, comparable stress in bone, implant, and abutment were found under 100 N vertical loading or 100 N vertical/50 N horizontal loading. In the R implant design, much higher stress in bone, implant, and abutment were found under 100 N vertical/50 N horizontal loading than that under 100 N vertical loading.

CONCLUSION

Irregular dental root-analog implant is a biomechanically favorable design principle for decreasing periimplant stress and strain under oblique loading.

Influence of Implant Neck Design on Bone Formation Under Mechanical Repetitive Loading: Histomorphometric and Microcomputed Tomographic Studies in Rabbit Tibiae

PURPOSE

The aim of this study was to investigate effects of implant neck design on the original concept of osseointegration and bone formation when applying mechanical repetitive loading by bone-integrated implants.

MATERIALS AND METHODS

Twenty-eight anodized Ti-6Al-4V alloy implants with +60° or -60° grooves in the implant neck were placed in the proximal tibial metaphysis of 14 rabbits. Fourteen implants received mechanical repetitive loading along the long axis of the implant for 8 weeks at 12 weeks after implant placement. The remaining 14 implants received no loading. Histomorphometric and microcomputed tomographic analyses were then performed.

RESULTS

No effect of neck design was observed without mechanical loading, whereas osseointegration around the +60° grooves was upregulated with mechanical loading. Calculated load effects on bone structure around the implant neck with +60° grooves were larger when compared with the -60° grooves under mechanical loading.

CONCLUSIONS

These findings indicate that the establishment of osseointegration and bone formation around the implant neck with +60° grooves is superior to those with -60° grooves under loaded conditions.

Effect of Microthread Design on Marginal Bone Level Around Dental Implants Placed in Fresh Extraction Sockets

PURPOSE

This study was designed to compare radiographically the effect of microthread on the coronal portion of the fixture on marginal bone level (MBL) around immediately placed dental implants in human subjects.

MATERIAL AND METHODS

Forty-one roughened surface screw type Dentium oral implants (Dentium) were inserted in fresh extraction sockets of the anterior segment of maxilla of 30 patients. The implants were selected randomly using either microthread design on coronal portion of the fixture (Implantium) (test group) or without microthread thread design (Superline) (control group). MBL was measured using digital subtraction radiography technique after 3, 6, and 12 months.

RESULTS

At month 3, the microthread groups have been associated with more marginal bone loss than the control group (P = 0.04). At months 6 and 12, both groups had comparable bone levels (P = 0.21).

CONCLUSION

The microthread design of the implant collar could not have a positive effect in maintaining the MBL around implants placed in fresh extraction socket in anterior maxilla.

Clinical, radiographic, and esthetic evaluation of immediately loaded laser microtextured implants placed into fresh extraction sockets in the anterior maxilla: a 2-year retrospective multicentric study

OBJECTIVES

To assess the clinical, radiographic, and esthetic outcomes of implants with a laser microtextured collar placed in the anterior region of the maxilla at the time of tooth extraction and immediately temporized.

METHODS

Forty-six Tapered Internal Laser-Lok BioHorizons implants were immediately placed and immediately restored with nonfunctional loading in 46 patients (24 men and 22 women) with a thick gingival biotype, ideal gingival level/contour, and postextraction intact walls. Survival rate, cortical bone loss, and periimplant mucosal responses were evaluated at 6, 12, and 24 months.

RESULTS

Survival rate was 95.6%. Mean mesial and distal marginal bone loss, 24 months after installation, were 0.58 mm (SD = 0.53; range, 0.17-1.15) and 0.57 mm (SD = 0.70; range, 0.42-1.10), respectively. A mesial and distal papilla regrowth mean of 1.8 and 1.5 mm, respectively, were found. The midfacial soft tissue levels showed 0.12 mm of mean recession after 24 months.

CONCLUSION

Immediate implants with a laser microtextured surface restored at the day of surgery, may be considered as a predictable procedure in terms of implant survival and hard and soft tissue remodeling.

A SIMPLE AND EFFICIENT METHODOLOGY TO IMPROVE DESIGN PROPOSALS OF DENTAL IMPLANTS — A DESIGN CASE STUDY

Objective: To propose a methodology based on virtual simulation to assist in the design proposals of dental implants. Methods: The finite element method (FEM) was used to analyze the biomechanical dental implant system behavior, determining von Mises stress distribution induced by functional loads, varying parameter as load direction and geometric characteristic of the implant (taper, length, abutment angulation, thread pitch and width pitch). A final design was obtained by considering the parameters that showed improved performance. The estimated lifetime of the final design was calculated by reproducing in a virtual way the experimental fatigue test required by the ISO:14801 standards. Results: For all the studied cases, the maximum stresses were obtained in the connecting screw under oblique loads (OLs). The estimated lifetime for this critical part is at least 5 × 106 cycles, which meets the requirement of the ISO:14801. In bone tissue, the largest stresses were concentrated in cortical bone, in the zone surrounding the implant, in good agreement with previous reports. Conclusions: A dental implant design was obtained and validated through a simple and efficient methodology based on the application of numerical methods and computer simulations.

Cemented and screw-retained implant-supported single-tooth restorations in the molar mandibular region: A retrospective comparison study after an observation period of 1 to 4 years

Objectives: The aim of this study was to evaluate the survival and compare the appearance of different mechanical and biological complications, in screw-retained and cemented-retained single-tooth implant-supported restorations localized in the molar mandibular region, over a period of 1 to 4 years. Material and Methods: A retrospective study was carried out with a total of eighty implant-supported restorations, which were placed in eighty patients for prosthetic rehabilitation of a mandibular molar. Forty patients were rehabilitated with a cemented-retained restoration and the other forty with a screw-retained restoration. The presence of the following complications was recorded for both types of prostheses: Fractures of the ceramic veneering, loosening screws, mucositis and peri-implantitis. Debonding of the restoration was analyzed in the cemented-retained restoration group. The clinical survival of crowns was analyzed with a Kaplan-Meier test and the clinical complications were compared, using a Student t test and Log-rank test. Results: 27 patients registered some complication. The average rate of complications was 37,5% for cemented-retained restorations and 30% for screw-retained restorations. The complications more common in the cemented-retained restoration were the presence of mucositis (14,87%), while in the screw-retained restorations was the loosening screw (20%). Student t test and Log-Rank test found significant differences (p=0,001) between the screw loosening and presence of mucositis. Conclusions: The cemented-retained restorations seem to prevent screw loosening, but the presence of cement seem to increase the complications around the soft tissues, however in the screw-retained restorations the presence of mucositis and peri-implantitis are lower than cemented-retained restorations. The incidence of fracture of ceramic veneering was similar in both groups.

Key words:Screw-retained restorations, cemented-retained restorations, screw loosening, peri-implant diseases and fracture ceramic veneering.

Mechanical design, analysis, and laboratory testing of a dental implant with axial flexibility similar to natural tooth with periodontal ligament

At the interface between the jawbone and the roots of natural teeth, a thin, elastic, shock-absorbing tissue, called the periodontal ligament, forms a cushion which provides certain flexibility under mechanical loading. The dental restorations supported by implants, however, involve comparatively rigid connections to the jawbone. This causes overloading of the implant while bearing functional loading together with neighboring natural teeth, which leads to high stresses within the implant system and in the jawbone. A dental implant, with resilient components in the upper structure (abutment) in order to mimic the mechanical behavior of the periodontal ligament in the axial direction, was designed, analyzed in silico, and produced for mechanical testing. The aims of the design were avoiding high levels of stress, loosening of the abutment connection screw, and soft tissue irritations. The finite element analysis of the designed implant revealed that the elastic abutment yielded a similar axial mobility with the natural tooth while keeping stress in the implant at safe levels. The in vitro mechanical testing of the prototype resulted in similar axial mobility predicted by the analysis and as that of a typical natural tooth. The abutment screw did not loosen under repeated loading and there was no static or fatigue failure.

Influence of platform switching on periimplant bone loss: a systematic review and meta-analysis

PURPOSE

This meta-analysis aims to systematically review and draw a comparison between conventional implant designs and "platform-switched" implants in terms of crestal bone loss.

MATERIALS AND METHODS

Electronic (PubMed) and hand searches were conducted. Literature, clinical studies, and case reports pertaining to reduction of crestal bone loss and obtaining better esthetic outcome by platform switching were reviewed till October 2011. Controlled trials comparing marginal bone-level changes around platform-switched and platform-matched implants were selected. For the assessment of accuracy, meta-analysis was performed.

RESULTS

The marginal bone loss around platform-switched implants was significantly lesser than platform-matched implants (mean difference [MD]: -0.34; 95% confidence interval [CI]: -0.37 to -0.30; P < 0.00001).

CONCLUSIONS

According to this review and meta-analysis, platform switching seems to preserve periimplant bone and soft tissue levels. However, long-term clinical studies on the proper diameter of abutment without deformation and the effective degree of platform switching in terms of the bone resorption are still awaited.

Immediate placement and loading of maxillary single-tooth implants: a 3-year prospective study of marginal bone level

AIM

The purpose of this study was to evaluate marginal bone level around single-tooth implants placed in anterior maxilla and immediately restored.

MATERIALS AND METHODS

Twenty implants were placed in 20 patients (8 men and 12 women) that were selected for this study. Following atraumatic non-surgical extraction of tooth, all patients immediately received implants and the definitive prefabricated abutment was placed. Implant position was transferred to the scanning unit of the CAD/CAM system using prefabricated surgical guide. Temporary crowns were immediately fabricated and cemented. Eight weeks later final crowns were luted. Outcome assessment as implant survival and level of marginal bone radiographic evaluations were performed at 8 weeks, 1 and 3 years time period after loading.

RESULTS

All implants placed osseointegrated successfully after 3 years of functional loading. The mean marginal bone loss was 0.16 mm (SD, 0.167 mm), 0.275 mm (SD, 0.171 mm) and 0.265 mm (SD, 0.171 mm) at 8 weeks, 1 and 3 years time period respectively. Four out of the 20 implants showed no bone loss.

CONCLUSION

Immediate loading technique using the final abutment directly eliminated the need for a second stage surgery and prevented interruption of soft and hard tissue at implant neck, which resulted in better soft tissue response and reduced marginal bone loss. Clinical significance: Immediately loaded implants, in fresh extraction sockets by insertion of a provisional restoration on the titanium abutment without any later manipulation, helped to protect the initially forming blood clot and presented a template for soft tissue contouring that resulted in significant reduction of marginal bone resorption and maintenance of soft tissue architecture.

Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

OBJECTIVE

To assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological, technical, and aesthetic complications. The focused question was: What is the survival rate of implants supporting single crowns and implant-supported crowns with a mean follow-up of 5 years and to which extent do biological, technical, and aesthetic complications occur?

METHODS

A Medline search (2006-2011) was performed for clinical studies focusing on implant-supported SCs with a mean follow-up of at least 5 years. The search was complemented by an additional hand search and the inclusion of 24 studies from a previous systematic review (Jung et al. 2008a). Survival and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5- and 10-year proportions.

RESULTS

Forty-six studies derived from an initial search count of 1083 titles and the complementary publications from the previous systematic review (Jung et al. 2008a) were selected and the data were extracted. Based on the meta-analysis, survival of implants supporting SCs at 5 years amounted to 97.2% (95% CI: 96.3-97.9%), and at 10 years amounted to 95.2% (95% CI: 91.8-97.2%). The survival of implant-supported SCs was 96.3% (95% CI: 94.2-97.6%) after 5 years and 89.4% (95% CI: 82.8-93.6%) after 10 years. For biological complications, a 5-year cumulative soft tissue complication rate of 7.1% (95% CI: 4.4-11.3%) and a cumulative complication rate for implants with bone loss >2 mm of 5.2% (95% CI: 3.1-8.6%) were calculated. Technical complications reached a cumulative incidence of 8.8% (95% CI: 5.1-15.0%) for screw-loosening, 4.1% (95% CI: 2.2-7.5%) for loss of retention, and 3.5% (95% CI: 2.4-5.2%) for fracture of the veneering material after 5 years. The cumulative 5-year aesthetic complication rate amounted to 7.1% (95% CI: 3.6-13.6%).

CONCLUSIONS

The outcomes of the meta-analysis demonstrated high implant survival rates for both the single tooth implants and the respective single crowns after 5 and 10 years. However, technical, biological, and aesthetic complications were frequent.

Biological aspects as a rule for single implant placement. The 3A-2B rule: a clinical report

For an implant restoration to be both esthetically and functionally successful, the prosthodontist must conduct a thorough treatment plan and complete a prosthesis design. The prosthodontist must carefully calculate the space needed for the restoration and soft tissue in the restoration process. The restoration and soft tissue are affected by the three-dimensional (3D) position of the implant, as the implant's depth determines the ideal length of the crown. When determining the 3D position of the implant, the clinician must consider the biological aspects required to ensure the restoration's biological integration with the patient's hard and soft tissues. The restoration must be the first component considered in the treatment plan. In addition, the clinician must understand that the distance between the cervical contour (of the planned restoration) and the level of the bone will dictate how the surgical and prosthetic treatment plan is enacted. In this report, a novel Radiographic Biological Ruler© (with biological information) was used to help facilitate the treatment plan's analysis.

Alveolar ridge resorption after tooth extraction: A consequence of a fundamental principle of bone physiology

It is well established that tooth extraction is followed by a reduction of the buccolingual as well as the apicocoronal dimension of the alveolar ridge. Different measures have been taken to avoid this bone modelling process, such as immediate implant placement and bone grafting, but in most cases with disappointing results. One fundamental principle of bone physiology is the adaptation of bone mass and bone structure to the levels and frequencies of strain. In the present article, it is shown that the reduction of the alveolar ridge dimensions after tooth extraction is a natural consequence of this physiological principle.

A 5-year retrospective clinical study of the Dentium implants

PURPOSE

The aim of this retrospective study was to evaluate cumulative survival rate (CSR) of Implantium implants followed for 5 years and association between risk factors and the CSR.

MATERIALS AND METHODS

A total of two hundred forty-nine Implantium Implants System (Dentium, Seoul, Korea) placed in ninety-five patients from 2004 to 2009 were investigated with several identified risk factors (sex, systemic disease, smoking, alchohol, reason of tooth loss, length, arch (maxilla or mandible), replace tooth type (incisor, canine, premolar or molar) Kennedy classification, prosthodontic type, prosthodontic design, opposite dentition, abutment type, occlusal material, occlusal unit, splint to tooth, cantilever, other surgery). Clinical examination (mobility, percussion, screw loosening, discomfort, etc.) and radiographic examination data were collected from patient records including all problems during follow-up period according to protocols described earlier. Life table analysis was undertaken to examine the CSR. Cox regression method was conducted to assess the association between potential risk factors and overall CSR.

RESULTS

Five of 249 implants were failed. Four of these were lost before loading. The 5-year implant cumulative survival rate was 97.37%. Cox regression analysis demonstrated a significant predictive association between overall CSR and systemic disease, smoking, reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The screw related complication was rare. Two abutment screw fractures were found. Another complications of prosthetic components were porcelain fracture, resin facing fracture and denture fracture (n=19).

CONCLUSION

The 5-year CSR of Implantium implants was 97.37%. Implant survival may be dependent upon systemic disease, smoking reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The presence of systemic diseases and combination of other surgical procedures may be associated with increased implant failure.

Cumulative survival rate of Astra Tech implants: a retrospective analysis

Purpose

The aim of this study was to analyze the short-term predictability and reliability of Astra Tech implants according to the demographical distribution of patients and condition of implant sites and location of implants.

Methods

Among patients treated with Astra Tech implant (Astra Tech AB) in the Department of Periodontology at the Dental Hospital of Yonsei University of College of Dentisry and K Dental Clinic from May 2004 to March 2009, 195 implants in 98 patients which had been restored more than 6 months ago were reviewed in this study. Following data were reviewed from patient charts and implants success rate was examined: 1) patient type and implant location, 2) bone status at the implant site, 3) diameter and length of the placed implants, 4) presence or absence of bone augmentation and types of the augmentation.

Results

The results from this study are as follows: 1) most implants were placed in the molar area, especially 1st molar area of maxilla, 2) most implants were placed at D2 and D3 bone type, 3) most implants were placed in areas of B and C bone quantity, 4) autogenous and alloplastic bone graft and artificial membrane were used for placement of 74 implants.

Conclusions

Short-term survival rate of Astra Tech implants was 100%.

Use of separate single-tooth implant restorations to replace two or more consecutive posterior teeth: a prospective cohort study for up to 1 year

PURPOSE

The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function.

MATERIALS AND METHODS

Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading.

RESULTS

All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year.

CONCLUSION

Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.