Technical and biological complications of single-molar implant restorations

What is the prevalence of peri-implantitis? A systematic review and meta-analysis

Background

Peri-implantitis is a usual finding but estimates of its prevalence fluctuate very much. This may be due to the wide variety of disease definitions. This systematic review aims to estimate the overall prevalence of peri-implantitis and the effect of different study designs, function times and use of probing depth on prevalence rate.

Methods

Following electronic and manual searches of the literature published from January 2005 to December 2021, data were extracted from the studies fitting the study criteria. Fifty-seven articles were included in this study.

Results

Prevalence of peri-implantitis was 19.53% (95% CI 12.87–26.19) at the patient-level, and 12.53% (95% CI 11.67–13.39) at the implant-level and it remains highly variable even following restriction to the clinical case definition. The use of probing depth like diagnostic criteria affected the prevalence data.

Conclusion

The results indicate that it remains essential the identification of the diagnostic markers for more accurate disease classification.

Does implant location influence the risk of peri-implantitis?

Peri-implantitis is characterized by nonreversible and progressive loss of supporting bone and is associated with bleeding and/or suppuration on probing. Peri-implant disease is considered as the main etiologic factor related to implant failure. Peri-implant disease has a pathogenesis similar to that of periodontal disease, both being triggered by an inflammatory response to the biofilm accumulation. Although the prevalence of peri-implantitis has been evaluated by several clinical studies with different follow-ups, there are currently little data on the impact of implant location and the prevalence of peri-implantitis. The aim of this review, therefore, was to summarize the evidence concerning the prevalence of peri-implantitis in relation to implant location and associated risk predictors. Even though most studies evaluating the prevalence of peri-implantitis in relation to implant location are cross-sectional or retrospective, they suggest that the occurrence of peri-implantitis is most prevalent in the anterior regions of the maxilla and mandible. Moreover, it seems that there is a higher prevalence of peri-implantitis in the maxilla than in the mandible.

Iatrogenic peri-implantitis - Factors interplaying the implant suprastructure design

FOCUSSED CLINICAL QUESTION

What is the key clinically controllable preventive measure that may help reduce the incidence of biological complications?

SUMMARY

Implant complications are common, ineffective care and delay in diagnosis can lead to expensive time-consuming surgical and non-surgical interventions. Careful selection and placement of implant allows development of adequate emergence design of the implant suprastructure. This helps achieve effective plaque control, adequate maintenance at hygiene visits, accurate follow up assessments of the peri-implant tissues addressing the key underlying factor impacting biological complications. This clinically controllable preventative measure may be considered a vital strategy in averting peri-implant disease.

CONCLUSION

Surge in biological complications have led to increased patient dissatisfaction in terms of time, cost, esthetics, and maintenance. One of the factors identified in causing biological complications is the iatrogenic prosthesis related factor. Minimizing the impact of this factor is crucial to the overall implant success. Selection and placement of implant following meticulous planning, using careful surgical protocols allows development of adequate suprastructure design that improves overall patient outcomes by reducing biological complications. Further research is essential to comprehensively assess the impact of these strategies in thwarting development of biological complications. This article is protected by copyright. All rights reserved Poor design of implant suprastructure leads to ineffective plaque control, inadequate maintenance, inaccurate follow up assessments predisposing to peri-implant disease. Selection and placement of implant based on available edentulous space and adjusting the running room can allow for better emergence of the suprastructure thus allowing proper oral hygiene. This clinically controllable preventative measure may be considered a vital strategy in averting peri-implant disease. Over-contoured suprastructure predisposes to peri-implantitis. Adjusting the running room during implant placement allows better emergence and effective plaque control.

A Single-Center Study of a Resin Inlay Dental Implant-Fixed Prosthesis for Closing Proximal Contact Loss in 89 Patients Who Underwent 3-Year Follow-Up

Background

Proximal contact loss (PCL) is very common between implant-fixed prostheses (IFPs) and adjacent teeth and leads to a high incidence of food impaction. Our aim was to determine if the mesio-distal adjustable (MDA) crown prostheses introduced in this study could easily establish new contacts intraorally without the intervention of prostheses retrieval.

Material/Methods

The MDA crown requires casting in the inlay framework at the proximal contact area. If PCL occurred, the resin in the inlay framework could be easily removed and refilled chairside. This single-center prospective study aimed to investigate the use of a resin inlay dental implant-fixed prosthesis for the closing proximal contact loss in 93 patients who were recruited from April 2017 to December 2017. Four patients dropped out during the 3-year follow-up; therefore, 89 patients were included. The effect of this technique was assessed by the implant mucosal status and follow-up investigations of food impaction.

Results

PCL occurred in 29.21% (26 prostheses) of the IFPs. The PCL rate at the mesial contact surfaces (n=24, 26.97%) was significantly higher than that at the distal contact surfaces (n=5, 8.33%) (P<0.01); however, the incidence of PCL was greater at adjacent teeth with significant bone resorption (P=0.00). After readjusting the resin inlay and closing the clearance, implant mucosal status and food impaction were significantly reduced (P<0.01).

Conclusions

The findings of this study showed that use of the MDA crown for closing PCL was time-saving and effective with satisfactory results at 3-year follow-up.

Effect of Abutment Geometry and Luting Agents on the Vertical Marginal Discrepancy of Cast Copings on Implant Abutments: An In Vitro Study

Aim

Vertical marginal discrepancy (VMD) influences the success of implant-supported restorations. However, there is little literature that has investigated the influence of geometry and cementing agent on changes in VMD of metal copings on implant abutments. The objective was to evaluate the effect of the geometry of the abutment and cementing agents on VMD.

Methods

Cast copings were cemented on implant abutments customized cylindrical (4, 5.5, and 7 mm) and on hexagonal implant abutments (4 mm) cemented or uncemented molded copings were placed (n = 4, totally 64 samples) with different luting agents. The VMD of the copings were measured in the coping-abutment interface at three reference points using a stereomicroscope. The independent Student's t test was used for comparison between the two different abutment walls. The post hoc statistical analysis was performed by the Tukey test.

Results

There was a significant VMD increase between noncemented and cemented cast copings using different luting agents. Abutment geometry and luting agents significantly influenced the VMD (p ≤ 0.05). Cylindrical abutment at 7 mm in height cemented with different luting agent tested showed significantly higher VMD values than cylindrical abutments of 4 mm (p=0.019). Hexagonal abutments with a 4 mm height showed significantly higher VMD values than cylindrical 4 mm abutments using zinc oxide noneugenol and glass ionomer cements (p=0.032).

Conclusions

Abutment geometry and luting agents influence the VMD of cast copings cemented on implant abutment. The higher the cylindrical abutment, the greater the VMD, and hexagonal wall abutments promote greater marginal gap.

Incidence and prevalence of peri-implantitis and peri-implant mucositis 17 to 23 (18.9) years postimplant placement

PURPOSE

To evaluate the prevalence of peri-implantitis (PI) and peri-implant mucositis (PM) in a long-term follow-up with comparison among different PI and PM definitions, and to report on the incidence of PI.

MATERIALS AND METHODS

In a retrospective clinical study five different PI and PM definitions were applied onto a population with 274 implants 17 to 23 years postimplant placement. Recommendations by the Eighth European Workshop on Periodontology (EWOP) were used as base reference. Clinical and radiological measurements were considered. Risk factors were evaluated in a regression analysis.

RESULTS

After an average observation period of 18.9 years, 40.1% of the implants were diagnosed with PM and 15.0% with PI (Eighth EWOP). PI incidence reached 7.9% on implant level and 13.2% on patient level. Implants diagnosed with PI and progressive bone loss displayed exceptionally vertical bone defect configuration (BDC). Diabetes mellitus, smoking, regular maintenance, or a former periodontal infection did not show significant influence on the prevalence of peri-implant diseases. Patients with bruxism displayed significantly less PM and PI.

CONCLUSIONS

Vertical BDC seems to correspond with active PI, wherefore we estimate such a defining factor of importance. Diagnosis of PM and evaluation of probing pocket depths might be only of descriptive interest as they could lead to false-positive results.

Mechanical fatigue behaviour of different lengths screw-retained restorations connected to two designs prosthetic connection level

The aim of this work is to compare the mechanical fatigue behaviour of different crown heights of single crown implant restorations made over two different internal hexagonal titanium dental implant connection levels. Two different groups of internal hexagonal connection were studied: (a) TL group (N = 26) included implants with a transmucosal connection (12.2 mm height and 4.8 mm width) and (b) BL group (N = 26) composed by implants at a bone level connection (10 mm height and 3.8 mm width). Two subgroups (N = 13) were established for each connection level according to crown heights (TL10 = 10 mm, TL15 = 15 mm, BL12 = 12 mm, BL17 = 17 mm). Dynamic load tests were carried out according to ISO Norm 14801. Failed samples and fracture surfaces were analysed with an optical and scanning electron microscope (SEM). The fatigue limit and the fatigue strength degradation (fatigue strength exponent) decreases with increasing crown height (5 mm) in both groups of internal hexagonal titanium dental implant connection levels. Consequently, the mechanical integrity of internal hexagonal dental implants varies with the height of the crown. An increase of 5 millimetres in the crown height appears to significantly decrease the fatigue life of both types of dental implants.

What is the Best Available Luting Agent for Implant Prosthesis?

Cement-retention is a viable option in restoring dental implants. A wide range of dental cements with different properties are commercially available for use in the cementation of implant prostheses. The selection of a dental cement for proper clinical application can be challenging. This article overviews the commercially available dental cements used in cement-retained implant-supported prostheses. Guidelines for cement selection are presented according to abutment and prosthetic material. Cementation techniques to reduce excess cement in peri-implant tissues are also mentioned.

Effect of loading frequency on cyclic fatigue lifetime of a standard-diameter implant with an internal abutment connection

OBJECTIVE

To investigate the effect of loading frequency on the fatigue lifetime of one standard-diameter titanium dental implant system.

METHODS

Thirty-six titanium dental implant specimens (Bone Level RC, Straumann) were assembled following manufacturer's instructions and torqued into cylindrical holder blocks following the apparatus specified by the ISO 14801 test standard. Stainless steel loading hemispheres were bonded on the abutments with a moment arm of 11mm. The holder blocks had layers of differing stiffness to simulate human jaw bone. Constant-stress fatigue lifetime testing was conducted at two frequencies (2Hz and 15Hz) with a stress ratio of 0.1 until fracture in deionized water at 37°C on servo-hydraulic load frames (MTS). The fractured specimens were retrieved and examined using fractographic technique to determine the failure mode. The lifetime data were fit to a general log-linear regression model.

RESULTS

The coefficient for the load amplitude term of the regression model indicated that increasing load amplitude had a statistically significant negative effect on the fatigue lifetime. The coefficients for the cyclic frequency term and the load-frequency interaction term were not significantly different from zero, which indicated that increasing loading frequency did not have an influence on the number of cycles to failure. Fractographic analysis showed that all specimens exhibited an identical combined fracture of abutment and abutment screw adjacent to the bone level.

SIGNIFICANCE

Higher loading frequency at least up to 15Hz may be used for future studies of some implant systems to improve the efficiency of fatigue testing.

In vitro fatigue tests and in silico finite element analysis of dental implants with different fixture/abutment joint types using computer-aided design models

PURPOSE

The aim of this study was to evaluate fatigue resistance of dental fixtures with two different fixture-abutment connections by in vitro fatigue testing and in silico three-dimensional finite element analysis (3D FEA) using original computer-aided design (CAD) models.

METHODS

Dental implant fixtures with external connection (EX) or internal connection (IN) abutments were fabricated from original CAD models using grade IV titanium and step-stress accelerated life testing was performed. Fatigue cycles and loads were assessed by Weibull analysis, and fatigue cracking was observed by micro-computed tomography and a stereomicroscope with high dynamic range software. Using the same CAD models, displacement vectors of implant components were also analyzed by 3D FEA. Angles of the fractured line occurring at fixture platforms in vitro and of displacement vectors corresponding to the fractured line in silico were compared by two-way ANOVA.

RESULTS

Fatigue testing showed significantly greater reliability for IN than EX (p<0.001). Fatigue crack initiation was primarily observed at implant fixture platforms. FEA demonstrated that crack lines of both implant systems in vitro were observed in the same direction as displacement vectors of the implant fixtures in silico.

CONCLUSIONS

In silico displacement vectors in the implant fixture are insightful for geometric development of dental implants to reduce complex interactions leading to fatigue failure.

Implant-supported overdentures with different bar designs: A retrospective evaluation after 5-19 years of clinical function

PURPOSE

This retrospective study evaluated the outcome of implant-retained overdentures (IODs) after 5-19 years of clinical function.

MATERIALS AND METHODS

A retrospective analysis of patient files was performed referring to 27 patients who received 36 IODs with 3 different bar designs (group A=prefabricated round bars, n=7; group B=one-piece anterior milled bars, n=20; and group C=two bilaterally placed milled bars, n=9) in the mandible (n=24) and/or in the maxilla (n=12). The analysis focused on the survival and success rates (according to Kaplan-Meier) of the implants and prostheses. Technical complication rates for each type of restoration were analyzed and compared via one-way ANOVA and the Chi-squared test. The prevalence of peri-implantitis (radiographic bone loss ≥3.5 mm) was evaluated by digital analysis of panoramic radiographs taken post-operative (baseline) and after 5-19 years of clinical function (follow-up).

RESULTS

The mean observational time was 7.3 years. The survival rates of the prostheses and implants were 100% and 97.7%, respectively. Technical complications occurred more frequently in group A (mean: 3.5 during observational time) than in the other two groups (B: 0.8; C: 1.0). However, this difference was not statistically significant (P=0.58). Peri-implantitis was diagnosed for 12.4% of the implants in 37% of the patients.

CONCLUSION

Bar-retained IODs are an adequate treatment option for edentulous jaws. These restorations may exhibit high implant/prosthesis survival rates (>97%), and a limited incidence of technical complications after a mean observational period of >7 years. Nevertheless, peri-implantitis was identified as a frequent and serious biological complication for this type of reconstruction.

Erythritol-Enriched Air-Polishing Powder for the Surgical Treatment of Peri-Implantitis

Peri-implantitis represents a major complication that can compromise the success and survival of implant-supported rehabilitations. Both surgical and nonsurgical treatment protocols were proposed to improve clinical parameters and to treat implants affected by peri-implantitis. A systematic review of the literature was performed on electronic databases. The use of air-polishing powder in surgical treatment of peri-implantitis was investigated. A total of five articles, of different study designs, were included in the review. A meta-analysis could not be performed. The data from included studies reported a substantial benefit of the use of air-polishing powders for the decontamination of implant surface in surgical protocols. A case report of guided bone regeneration in sites with implants affected by peri-implantitis was presented. Surgical treatment of peri-implantitis, though demanding and not supported by a wide scientific literature, could be considered a viable treatment option if an adequate decontamination of infected surfaces could be obtained.