Parameters Associated with Marginal Bone Loss around Implant after Prosthetic Loading

Comparison of Stress and Strain Distribution Patterns in Canine Implant and Maxillary Bone in Three Occlusal Schemes Using Finite Element Analysis

OBJECTIVES

 This study aimed to compare the pattern of stress and strain distribution in canine implant and maxillary bone in the anterior group function (AGF), posterior group function (PGF), and canine guidance (CG) occlusal schemes by finite element analysis (FEA).

MATERIAL AND METHODS

 In this in vitro experimental study, a dental implant (10 × 4.1 mm) was inserted at the site of the maxillary canine in a model of the maxilla in Mimics software. The implant was scanned three-dimensionally and the data were transferred to SolidWorks software. The von Mises stress, shear stress, deformation, and strain were calculated in the AGF, PGF, and CG occlusal schemes by FEA.

STATISTICAL ANALYSIS

 Data were analyzed by ABAQUS software to calculate the stress transferred to the canine implant and maxillary bone in the three occlusal schemes.

RESULTS

 The maximum and minimum von Mises stress, elastic strain, shear stress, and deformation were noted in the AGF and PGF occlusal schemes, respectively, in all teeth.

CONCLUSION

 The PGF showed minimum von Mises stress, elastic strain, shear stress, and deformation in the canine implant and maxillary bone. Thus, it appears than the PGF is the best occlusal scheme for maxillary canine implant followed by the CG scheme.

Clinical Outcomes of Three versus Four Mini-Implants Retaining Mandibular Overdenture: A 5-Year Randomized Clinical Trial

Background and Objectives: Due to a lack of long-term clinical studies that would clarify whether the insertion of three mini-implants (MDIs) can be as successful treatment as the insertion of four MDIs for the retention of mandibular overdentures (ODs), this 5-year prospective cohort study was set up. Materials and Methods: Participants (n = 83) randomly received either four or three MDIs and a mandibular OD. Clinical examinations were performed at the baseline, as well as after one, three, and five years, respectively. A total of 73 participants (38 in the four-MDI and 35 in the three-MDI groups) partook in the study. The marginal bone level change, success and survival rates, and prosthodontic maintenance were assessed. Results: Repeated measures showed that the mean peri-implant bone loss increased progressively at a small amount over five years in both groups (four-MDI group = -0.36 ± 0.74; three-MDI group = -0.33 ± 0.27 mm; p < 0.05). However, an ANCOVA revealed no significant effects of the group (no significant difference between the three- and the four-MDI groups; F = 0.085; p = 0.771), gender (F = 0.023; p = 0.88), or covariate age (F = 1.95; p = 0.167) on the dependent variable: the 5-year MBL change. The success rate (together with successful survival) was 93.8% in the four-MDI group and 91.7% in the three-MDI group. The log-rank (Mantel-Cox) test revealed no significant differences between them (X2 = 0.373; p = 0.541). Conclusions: In patients with narrow ridges, the insertion of three MDIs in the mandible for overdenture retention can be equally as successful as the insertion of four MDIs.

Early Implant Bone Loss in the Preprosthetic Phase: A Retrospective Study

Initiation of the inflammatory response begins with the surgical placement of an implant that stimulates bone remodeling. The occurrence of crestal bone loss during submerged healing affects the prognosis of an implant. Hence, this study was conducted to estimate the early implant bone loss during the preprosthetic phase on bone level implants placed equicrestally. This retrospective observational study included evaluation of crestal bone loss around 271 two-piece implants placed in 149 patients from the archived postsurgical (P1) and preprosthetic (P2) digital orthopantomographic records using MicroDicom software. The outcome was categorized based on (1) sex (male or female), (2) time of implant placement (immediate [I] vs conventional [D]), (3) duration of healing period before loading (conventional [T1] vs delayed [T2]), (4) region of implant placement (maxilla [M1] vs mandible [M2]), and (5) site of implant placement (anterior [A] vs posterior [P]). To find the significant difference between the bivariate samples in the independent groups, an unpaired sample t test was used. The average marginal bone loss during the healing phase was 0.56 ± 0.573 mm in the mesial region and 0.44 ± 0.549 mm in the distal region of the implant, with a statistically significant difference (P < .01). There was no statistically significant difference in crestal bone level with the (1) sex of the patient (male or female), (2) type of implant placement (I or D), (3) time of implant loading (T1 or T2), (4) region of implant placement (M1 or M2), or (5) site of implant in the arch (A or P) (P > .05). An average of 0.50 mm crestal bone loss occurred in the peri-implant region during the preprosthetic phase. We found that the delayed placement of an implant and a delay in the healing period would further increase the early implant bone loss. The difference in the healing period did not alter the outcome of the study.

Effect of the implant apical exposure and coverage < or ≥ 2 mm bone graft on transcrestal sinus floor elevation: a 1- to 7-year retrospective cohort study

OBJECTIVES

This study aimed to analyze the effect of the apex coverage by the bone graft, including exposure and coverage less than or greater than 2 mm on implant survival rate and peri-implant bone and soft tissue remodeling.

MATERIALS AND METHODS

A total of 264 implants in 180 patients who had undergone transcrestal sinus floor elevation (TSFE) with simultaneous implant placement were included in this retrospective cohort study. Radiographic assessment was used to categorize the implants into three groups based on apical implant bone height (ABH): ≤ 0 mm, < 2 mm, or ≥ 2 mm. The implant survival rate, peri-implant marginal bone loss (MBL) during short-term (1-3 years) and mid- to long-term (4-7 years) follow-up, and clinical parameters were used to evaluate the effect of implant apex coverage after TSFE.

RESULTS

Group 1 had 56 implants (ABH ≤ 0 mm), group 2 had 123 implants (ABH > 0 mm, but < 2 mm), and group 3 had 85 implants (ABH ≥ 2 mm). There was no significant difference in the implant survival rate between groups 2 and 3 compared to group 1 (p = 0.646, p = 0.824, respectively). The MBL during short-term and mid- to long-term follow-up indicated that apex coverage could not be considered a risk factor. Furthermore, apex coverage did not have a significant effect on other clinical parameters.

CONCLUSIONS

Despite limitations, our study found that implant apex coverage by the bone graft, including exposure and coverage levels less than or greater than 2 mm, did not significantly affect implant survival, short-term or mid- to long-term MBL, or peri-implant soft tissue outcomes.

CLINICAL RELEVANCE

Based on 1- to 7-year data, the study suggests that implant apical exposure and coverage levels of less than or greater than 2 mm bone graft are both valid options for TSFE cases.

Marginal bone loss of tissue- or bone-level implants after simultaneous guided bone regeneration in the posterior mandibular region: A retrospective cohort study

PURPOSE

To analyze the marginal bone loss (ΔMBL) of tissue- or bone-level implants after placed with simultaneous guided bone regeneration (GBR).

MATERIALS AND METHODS

A total of 151 patients who received 104 tissue-level or 128 bone-level implants placement with simultaneous GBR in the mandibular posterior region between January 2011 and December 2016 were included in this study. The marginal bone level (MBL) was recorded using the radiographic data obtained at implant placement, second-stage surgery, and the follow-up visit. Generalized estimating equation (GEE) was used to compare the ΔMBL of tissue- and bone-level implants, and the influencing factors of ΔMBL were further analyzed.

RESULTS

At the last follow-up visit, the MBL of tissue-level implants was 0.73 ± 0.86 mm, above the rough-smooth interface, while that of bone-level implants was 0.82 ± 1.05 mm, above the implant platform. The ΔMBL of tissue-level implants was 1.03 mm, which was slightly higher than 0.81 mm of bone-level implants, but there was no significant difference (p > 0.05). No contributing factor associated with ΔMBL was identified by multivariate regression analysis in this study.

CONCLUSION

Within the limits of this retrospective analysis, the ΔMBL of tissue-level implants is similar to that of bone-level implants after placed with simultaneous GBR, and both types of implants can achieve desirable marginal bone stability.

Marginal bone loss around dental implants: comparison between matched groups of bruxer and non-bruxer patients: A retrospective case-control study

PURPOSE

To compare marginal bone loss (MBL) around dental implants in a group of bruxers in relation to a matched group of non-bruxers.

METHODS

The present record-based retrospective study included patients selected from individuals treated with dental implants at one specialist clinic in Malmö. Only implants not lost and with baseline radiographs taken within 12 months after implant placement and with a minimum of 36 months of radiological follow-up were considered for inclusion. Univariate linear regression models and a linear mixed-effects model were performed.

RESULTS

Two hundred and four patients (104 bruxers, 100 non-bruxers), with a total of 811 implants (416 in bruxers, 395 in non-bruxers) were included in the study. The results of the linear mixed-effects model suggested that bruxism, smoking, age, region of the jaws, implant diameter, and prosthesis type had a statistically significant influence on MBL over time. Individuals who are both bruxers and smokers showed greater MBL when compared to individuals who are either a bruxer or smoker, or neither (p < 0.001).

CONCLUSIONS

Bruxism is suggested to increase the risk of MBL over time, as well as higher age, smoking, and the combination of bruxism and smoking. Other factors that showed a correlation with increased MBL were implant diameter, region of the jaws, and prosthesis type, but it is not possible to draw robust conclusions for these factors, as the categories of these variables were very unbalanced.

Stresses induced by one piece and two piece dental implants in All-on-4® implant supported prosthesis under simulated lateral occlusal loading: non linear finite element analysis study

Background

Correct choice of the implant design and the occlusal scheme is important for the success of implant supported restorations. So, the aim of the current study was to find out the difference in the stresses induced by the one piece dental implants designed to be used in the All-on-4® concept and the conventional two piece ones under simulated lateral occlusal schemes using nonlinear finite element analysis.

Methods

Two finite element models of the maxilla, implants, and prostheses were designed according to the All-on-4® concept. In the model TP, two piece dental implants were placed while in the model OP one piece dental implants were used. Two loading scenarios were applied to each model; the first one simulated a group function occlusal scheme while the second scenario simulated a canine guided one.

Results

The highest stress value was recorded in the model TP with the group function occlusion and the lowest stress value was in the model OP with the canine guidance occlusion.

Conclusion

The one-piece dental implants can be concluded to induce less stress compared to the two piece dental implants when used in the All-on-4® implant supported prosthesis in the different lateral occlusal schemes. Canine guided occlusion can be concluded to cause lower stress values in comparison to the group function occlusal scheme.

Marginal Bone Loss around Implant-Retaining Overdentures versus Implant-Supported Fixed Prostheses 12-Month Follow-Up: A Retrospective Study

Few studies have compared marginal bone loss (MBL) around implant-retaining overdentures (IODs) vs. implant-supported fixed prostheses (FPs). This study evaluated the mean MBL and radiographic bone-implant interface contact (r-BIIC) around IODs and implant-supported FPs. We also investigated osseointegration and MBL around non-submerged dental implants. We measured the changes between the MBL in the mesial and distal sites immediately after prosthetic delivery and after one year. The mean MBL and its changes in the IOD group were significantly higher. The mean percentage of r-BIIC was significantly higher in the FP group. MBL and its changes in males were significantly higher in the IOD group. The percentage of r-BIIC was significantly higher in the FP group. MBL in the lower site in the IOD group was significantly higher. Regarding MBL, the location of the implant was the only significant factor in the IOD group, while gender was the only significant predictor in the FP group. Regarding the r-BIIC percentage, gender was a significant factor in the FP group. We concluded that non-submerged dental implants restored with FPs and IODs maintained stable bone remodeling one year after prosthetic delivery.

Survival Rates of Splinted and Nonsplinted Prostheses Supported by Short Dental Implants (≤8.5 mm): A Systematic Review and Meta-Analysis

PURPOSE

To evaluate and compare the implant survival rates, marginal bone loss, and mechanical complications of prostheses supported by splinted and nonsplinted short implants (≤8.5 mm).

MATERIAL AND METHODS

Electronic database (MEDLINE, CENTRAL, Web of Science, and EMBASE) and manual searches up to May 2021 were conducted to identify studies comparing splinted and nonsplinted short implants (≤8.5 mm). The primary outcome was implant survival rate. Secondary outcomes were marginal bone loss and mechanical complications. The quality of included studies and risk-of-bias were assessed according to the Newcastle-Ottawa Scale. A random-effects model was used to analyze the data.

RESULTS

Twelve studies fulfilled the inclusion criteria and featured 1506 short implants (596 nonsplinted and 910 splinted) with a follow-up time ranging from 1 to 16 years. Quantitative analysis found no statistically significant differences between splinted and nonsplinted short implants (≤8.5 mm) for survival rate (RR = 0.98; 95% CI 0.96, 1.01; p = 0.26)) and marginal bone loss (SMD = -0.08; 95% CI - 0.23, 0.07; p = 0.28). Veneer chipping, abutment screw breakage, screw loosening, and loss of retention were reported in the selected studies as common complications. However, no statistically significant difference was found between splinted and nonsplinted short implants (RR = 0.56; 95% CI 0.20, 1.54; p = 0.26).

CONCLUSIONS

Within the limitations of the present meta-analysis, it might be concluded that splinted short implants (≤8.5 mm) do not present superior performance in survival rate, marginal bone maintenance and prevention of mechanical complications compared with single-unit prostheses.

Guided bone regeneration simultaneous with implant placement using bovine-derived xenograft with and without liquid platelet-rich fibrin: a randomized controlled clinical trial

OBJECTIVE

To assess augmentation success after guided bone regeneration (GBR) carried out simultaneously with implant placement using bovine-derived xenograft alone and in combination with liquid platelet-rich fibrin (liquid-PRF).

METHODS

This randomized controlled clinical trial was conducted on patients with horizontal bone deficiency in the posterior regions of the mandible. After implant placement, GBR procedures were randomly performed using liquid-PRF-enriched bovine-derived xenograft (for the test group) and with bovine-derived xenograft alone (for the control group). To assess the change in augmentation thickness, the primary outcome of the study, cone beam computed tomography was carried out at the implant sites on completion and 6 months after surgery. The secondary outcomes were marginal bone level and implant survival rate at prosthetic delivery and at 6 months, 1 year, and 2 years follow-up after loading. The significance level was set at p<0.05 for all analysis.

RESULTS

Twenty patients with 50 implants were analyzed for the test group and 20 patients with 48 implants for the control group. At 6 months postoperatively, the mean values of augmentation thickness were 1.63 ± 0.21 mm, 2.59 ± 0.34 mm, and 3.11 ± 0.36 mm for the test group and 1.34 ± 0.14 mm, 2.49 ± 0.24 mm, and 2.97 ± 0.24 mm for the control group at 2 mm, 4 mm, and 6 mm below to the implant shoulder (p < 0.001, p = 0.007, and p = 0.036, respectively). The mean marginal bone loss was found to be less than 1 mm for both study groups during the 2 years of follow-up after prosthetic loading. Implant survival rate was 100% for both study groups.

CONCLUSION

Bovine-derived xenograft alone and in combination with liquid-PRF are both successful in achieving bone augmentation around the implants and produce a small change in marginal bone level and a high implant survival rate after loading.

CLINICAL RELEVANCE

There is a lack of evidence in the literature regarding the augmentation success of liquid-PRF used in combination with bone graft substitutes. This study indicates that liquid-PRF could be used as a supportive material with bovine-derived xenograft in GBR procedures carried out simultaneously with implant placement.

Peri-implant marginal bone changes with implant-supported metal-ceramic or monolithic zirconia single crowns: A retrospective clinical study of 1 to 5 years

STATEMENT OF PROBLEM

Monolithic zirconia has excellent mechanical and biologic properties. However, evidence of the clinical properties of implant-supported monolithic zirconia prostheses is limited.

PURPOSE

The purpose of this retrospective clinical study was to compare the peri-implant marginal bone changes of metal-ceramic and monolithic zirconia single crowns in the posterior region after prosthetic loading.

MATERIAL AND METHODS

A total of 224 participants treated with 327 implants restored with either metal-ceramic or monolithic zirconia single crowns in the posterior region between 2012 and 2016 were included in this study. Clinical outcomes, including the plaque index, peri-implant probing depth, and bleeding on probing, were recorded, and the marginal bone level was recorded by using the panoramic radiographs obtained at implant placement, second-stage surgery, and the most recent follow-up visit. The included parameters were analyzed with the nonparametric Mann-Whitney tests (α=.05).

RESULTS

The mean follow-up time was 30.4 months, and the cumulative survival rate of implants was 100% and that of the prostheses was 99.1%. The plaque index was 0.46 in the metal-ceramic group, which was significantly higher (P<.05) than 0.37 in the monolithic zirconia group. However, no significant differences (P>.05) were observed in peri-implant probing depth and bleeding on probing between the 2 groups. The marginal bone level at implant placement, second-stage surgery, and the most recent follow-up visit was above the implant platform in both the metal-ceramic and monolithic zirconia groups. The marginal bone changes of the metal-ceramic group was 0.31 mm in the healing period and 0.38 mm in the prosthetic loading period, while in the monolithic zirconia group, it was 0.25 mm in the healing period and 0.43 mm in the prosthetic loading period; no significant differences (P>.05) were observed between the 2 groups.

CONCLUSIONS

The peri-implant marginal bone level change was comparable after prosthetic loading for metal-ceramic and monolithic zirconia single crowns, although monolithic zirconia was associated with reduced plaque.

Fractures of implant fixtures: a retroscccpective clinical study

BACKGROUND

The aim of this study was to evaluate the factors that may affect implant fixture fractures.

METHODS

Patients who experienced implant fixture removal at Seoul National University Bundang Hospital from 2007 to 2015 due to implant fixture fracture were included. Implant/crown ratio, time of implant fracture, clinical symptoms before implant fracture, treatment of fractured implants, and the success and survival rate of the replaced implants were evaluated retrospectively.

RESULTS

Thirteen implants were fractured in 12 patients. Patient mean age at the time of fracture was 59.3 years. Of the 13 implants, 7 implants were placed at our hospital, and 6 were placed at a local clinic. The mean crown/implant ratio was 0.83:1. The clinical symptoms before fracture were screw loosening in five implants, marginal bone loss in five implants, and the presence of peri-implant diseases in five implants. All the fractured implants were removed, and 12 out of the 13 sites were re-implanted. Parafunctions were observed in two patients: one with bruxism and one with attrition due to a strong chewing habit.

CONCLUSIONS

Several clinical symptoms before the fracture of an implant can predict implant fixture failure. Therefore, if these clinical symptoms are observed, appropriate treatments can be taken before more serious complications result.

Marginal bone loss around oral implants supporting fixed versus removable prostheses: a systematic review

Aim

The aim of this systematic review was to evaluate and compare the marginal bone loss (MBL) around implants of fixed (FISP) versus removable implant-supported prosthesis (RISP).

Material and methods

This review was conducted according to the PRISMA guidelines. A systematic search of the literature on Web of Science and Ovid (MEDLINE) was conducted in March 2019 to identify randomized controlled trials/quasi-randomized trials, prospective and retrospective studies written in German and English. Two reviewers screened the identified papers for eligibility and performed an independent data extraction. The Newcastle-Ottawa Scale was used to evaluate the level of evidence of the included studies.

Results

The search resulted in 2577 studies, of which 42 were selected for full-text evaluation. Finally, six studies were included in qualitative analyses, reporting results from 248 participants (81 FISP versus 167 RISP). Five of the included studies were prospective and one study was retrospective. MBL was highest in the first year after implant placement and ranged from 0.17 ± 0.07 mm to 2.1 ± 1.6 mm in FISP and from 0.22 ± 0.55 mm to 2.5 ± 2.7 mm in RISP. After 4 years, there was no statistically significant difference between the groups; MBL ranged from 0.36 ± 0.22 mm to 1.5 mm in FISP and 0.56 ± 0.45 mm to 1.4 mm in RISP. Of the six included studies, two each were rated as good quality, fair quality, and poor quality.

Conclusion

Fixed and removable implant-supported prostheses seem to have similar long-term outcomes regarding marginal bone loss. However, the evidence provided in this systematic review is limited due to the poor quality of two of the included studies. Future studies with study designs specified to the topic of this review are necessary to provide clear information about marginal bone level alterations in modern implant therapy.

Tooth discoloration caused by endodontic treatment: A cross-sectional study

INTRODUCTION

This cross-sectional study evaluated the influence of endodontic filling material, cervical limit of root filling, and tooth location on the color variation (∆E₀₀ ) from 1 to 60 months of follow-up.

MATERIALS AND METHODS

Color records were obtained from 70 participants who received 83 endodontic treatments. CIEL*a*b* color coordinates were measured on the homologous tooth, which was considered as baseline, and on endodontic treated teeth with a spectrophotometer. ∆E₀₀ was calculated by the CIEDE2000 method at three conditions (condition 1: homologous tooth vs endodontically treated tooth after ≤1 month; condition 2: homologous tooth vs endodontically treated tooth after >1-12 months; condition 3: homologous tooth vs endodontically treated tooth after >12 months up to 5 years) for each variable. The zinc oxide and eugenol mineral trioxide aggregate or resin-based filling materials, dental cervix or ≥2 mm in the apical direction cervical limit of root filling and anterior or posterior tooth location were considered in the comparisons. Confidence intervals for the means (95% CI) were calculated, ∆E₀₀ values and CIEL*a*b* individual color coordinates were compared for each pair of variables using the Student t test or Welch test (α = .05).

RESULTS

Greater ∆E₀₀ values were generally observed in the condition 3 for cervical limit (∆E₀₀ = 10.7), use of zinc oxide and eugenol and mineral trioxide aggregate-based filling materials (∆E₀₀ = 10.7), and anterior teeth (∆E₀₀ = 12.4). Only in the condition 1, the ∆E₀₀ values of the filling materials did not show statistical differences (P = .198).

CONCLUSIONS

Higher ∆E₀₀ values were yielded from zinc oxide and eugenol and mineral trioxide aggregate-based filling materials, anterior teeth, and dental cervix cervical limit of root filling.

CLINICAL SIGNIFICANCE

Tooth discoloration yielded by endodontic materials and procedures is a challenge to clinical practice resulting in aesthetic problems and discomfort to both patient and professional, especially when it occurs in anterior teeth.

Comparison of stress in implant-supported monolithic zirconia fixed partial dentures between canine guidance and group function occlusal patterns: A finite element analysis

Background. Monolithic zirconia is an emerging material for crowns and bridges. The possibility of full digital design has made it an attractive alternative material for implant-supported prostheses. A proper design is vital in the success of such a prosthesis like any other. This study, in the shortage of scientific evidence, has tried to assess the stress distribution of occlusal forces inside the implant-prosthesis system of a 3-unit bridge made of monolithic zirconia. Methods. A 3-unit monolithic zirconia bridge supported by two implant fixtures placed on the teeth #13 and #15 was digitalized. It was converted to a mesh of 59000 nodes and 34000 elements. Five types of occlusal forces (one as vertical centric, two at 15º and 30º simulating canine pattern of lateral movement, and two at 15º and 30º simulating group function pattern) were applied. The stress distribution among all the components of the implant-bridge system was assessed using Ansys Workbench 14 software and finite element analysis. Results. The maximum stress was between 286 and 546 MPa, which were found in either the fixture‒abutment screw area or in the upper part of the pontic connector between the canine and first premolar. The maximum pressure increased with an increase in the angle of occlusal force. Significantly higher stress was recorded in the group function occlusal pattern. Conclusion. Monolithic zirconia can be promising in designing bridges in the canine‒premolar area. However, proper design is necessary with more attention to the connectors and types of occlusal forces.

Implant supported cantilevered fixed dental rehabilitations in partially edentulous patients: Systematic review of the literature. Part I

OBJECTIVES

To investigate in which clinical situations a cantilever fixed implant supported restorations can be a treatment alternative and which complications are reported.

MATERIALS AND METHODS

Two operators screened the literature (MEDLINE, EMBASE) and performed a hand search on the main journals dealing with implantology and prosthetics until 31 December 2017. Only articles that considered cantilever implant fixed restorations with at least 10 patients and with a mean follow-up of at least 5 year were selected. The outcome variables were survival of implants and prosthesis, mechanical, technical and biological complications, marginal bone loss. The review was performed according to the PRISMA statements. Risk of bias assessment was evaluated. Failure and complication rates were analysed using random effect Poisson regression models to obtain summary estimate of 5- and 10-year survival and complication rates.

RESULTS

A total of nine papers were selected for partially edentulous patients and reported high survival rate of the prosthesis. The estimated survival rate for 5-10 years was calculated to be 98.4% for the implants and 99.2% for the rehabilitations. Mechanical, technical and biological complications were reported with a cumulative 5-10 years complication rate of 28.66% and 26.57% for the patients and for the prosthesis, respectively. Two papers for single implant supporting 2-unit cantilever were not sufficient to draw conclusions.

CONCLUSIONS

There is evidence that cantilever can be successful treatment in partially edentulous patients. In two adjacent edentulous sites, data are not yet sufficient.

Marginal bone loss around cement and screw-retained fixed implant prosthesis

Background

Implant-supported fixed restorations are considered as the standard treatment for replacement of missing teeth. These can be either screw or cement retained. The success or failure of implant restorations depend upon amount of marginal bone loss (MBL). The present study is to determine the MBL around cement and screw-retained implant prosthesis and to determine various predictors of the MBL.

Material and Methods

A retrospective charts review was conducted at the dental clinics, Aga Khan University Hospital, Karachi from February 2017 to June 2017 in which 104 implants restorations were assessed using periapical radiographs. MBL was calculated at baseline and at 12 months and the difference was recorded on a proforma. SPSS version 21.0 was used for statistical analysis. Descriptive statistics was computed. Generalized estimation equation analysis (GEE) was applied to determine the predictors of MBL. Level of significance was kept at ≤ 0.05.

Results

There were 104 implant restorations belonging to 41 patients. Screw retained prosthesis showed significantly greater MBL than cement retained prosthesis (p-value =0 .018) (irrespective of crowns or fixed partial dentures). Other factors that turned out to be significant predictors of MBL were male gender (p-value= <0.01), age >65 yrs. (p-value=0.028) and sites where bone grafting was performed (p-value=0.003).

Conclusions

Male patients of age >65 yrs. with sites needing bone grafts who were provided with screw retained prosthesis (irrespective of crown or fixed partial dentures) had significantly greater marginal bone loss around implants. Key words:Dental implants, dental prosthesis, implant supported dental prosthesis, alveolar bone loss.

Survival rates of hybrid rough surface implants and their alveolar bone level alterations

BACKGROUND

The design of hybrid surface implants takes advantage of characteristics of two different textures to improve clinical outcomes. To date, there are limited numbers of studies reporting the clinical results of hybrid surface implants. This study aimed to assess hybrid surface implants with two different rough textures in regard to survival, marginal bone level change, and biological complications.

METHODS

Retrospective review of dental records was conducted for 161 patients who had 460 hybrid surface implants to analyze survival rate. These implants had the dual sandblasted and anode oxidized surface. Sixty patients with 192 implants who had consecutive radiographs taken at specific time points and complete clinical examinations were included in the comprehensive analysis. The associations between patient- and implant-related characteristics, and clinical results were analyzed by log-rank test, Cox regression, and linear regression analysis.

RESULTS

Cumulative survival at 12, 36, and 60 months after placement was 97.4%, 96.4%, and 95.8%, respectively. The average marginal bone level change from baseline to the last visit was 0.31 ± 0.68 mm and 0.34 ± 0.77 mm at the mesial and distal sites, respectively. Prevalence of peri-implantitis was 0.5% at the implant level and 1.7% at the patient level. Implant site was associated with implant failure (P = 0.03). Smoking habit, history of periodontitis, and implant site were significantly associated with marginal bone level change (P = 0.001, < 0.001, 0.01, respectively).

CONCLUSIONS

Hybrid rough surface implants had high survival rate, stable bone level, and low prevalence of biological complications. This surface design demonstrated promising clinical outcomes. More studies are needed to further support the clinical advantages of hybrid surface implants.

Position paper for the evaluation and management of oral status in patients with valvular disease: Groupe de Travail Valvulopathies de la Société Française de Cardiologie, Société Française de Chirurgie Orale, Société Française de Parodontologie et d'Implantologie Orale, Société Française d'Endodontie et Société de Pathologie Infectieuse de Langue Française

Oral health is of particular importance in patients with heart valve diseases because of the risk of infective endocarditis. Recommendations for antibiotic prophylaxis before dental procedures have been restricted, but the modalities of oral evaluation and dental care are not detailed in guidelines. Therefore, a multidisciplinary working group reviewed the literature to propose detailed approaches for the evaluation and management of buccodental status in patients with valvular disease. Simple questions asked by a non-dental specialist may draw attention to buccodental diseases. Besides clinical examination, recent imaging techniques are highly sensitive for the detection of inflammatory bone destruction directly related to oral or dental infection foci. The management of buccodental disease before cardiac valvular surgery should be adapted to the timing of the intervention. Simple therapeutic principles can be applied even before urgent intervention. Restorative dentistry and endodontic and periodontal therapy can be performed before elective valvular intervention and during the follow-up of patients at high risk of endocarditis. The detection and treatment of buccodental foci of infection should follow specific rules in patients who present with acute endocarditis. Implant placement is no longer contraindicated in patients at intermediate risk of endocarditis, and can also be performed in selected high-risk patients. The decision for implant placement should follow an analysis of general and local factors increasing the risk of implant failure. The surgical and prosthetic procedures should be performed in optimal safety conditions. It is therefore now possible to safely decrease the number of contraindicated dental procedures in patients at risk of endocarditis.

A comparison of peri-implant strain generated by different types of implant supported prostheses

AIMS AND OBJECTIVE

To find out and compare peri implant strain developed in four different types of implant supported prostheses i.e., cement retained splinted, cement retained non splinted, screw retained splinted, screw retained non splinted.

METHODOLOGY

Four implant analogues were placed in a polyurethane mandibular model at the position of left and right first and second molar. Abutments were fixed to the implant at a torque of 25Ncm. Two such models were made. Four different prostheses were placed on abutment of each model i.e screw retained splinted, screw retained nonsplinted, cement retained splinted, cement retained non splinted. Four strain gauges were attached on the model, two on the buccal and two on the lingual aspect of each implant. Static load of 400N was applied on the prosthesis using universal testing machine. Load application was done ten times for each model and peri implant strain was measured.

RESULTS

The mean peri implant strain (±SD) generated was found to be highest in non-splinted screw retained (1397.70 ± 44.47 microstrains and 1265.90 ± 42.76 microstrains) and least in splinted cement retained (630.70 ± 31.98 microstrains and 519.60 ± 32.48 microstrains) in both 1st and 2nd molars respectively.

CONCLUSIONS

Splinted crowns produce less peri implant strain when compared to non splinted crowns. Cement retained prosthesis produce less peri implant strain when compared to screw retained prosthesis. Least strain was observed in cement retained splinted crowns.

Long-Term Fatigue and Its Probability of Failure Applied to Dental Implants

It is well known that dental implants have a high success rate but even so, there are a lot of factors that can cause dental implants failure. Fatigue is very sensitive to many variables involved in this phenomenon. This paper takes a close look at fatigue analysis and explains a new method to study fatigue from a probabilistic point of view, based on a cumulative damage model and probabilistic finite elements, with the goal of obtaining the expected life and the probability of failure. Two different dental implants were analysed. The model simulated a load of 178 N applied with an angle of 0°, 15°, and 20° and a force of 489 N with the same angles. Von Mises stress distribution was evaluated and once the methodology proposed here was used, the statistic of the fatigue life and the probability cumulative function were obtained. This function allows us to relate each cycle life with its probability of failure. Cylindrical implant has a worst behaviour under the same loading force compared to the conical implant analysed here. Methodology employed in the present study provides very accuracy results because all possible uncertainties have been taken in mind from the beginning.