The influence of crown-to-implant ratio on marginal bone levels around splinted short dental implants: A radiological and clincial short term analysis

Correlation of two different devices for the evaluation of primary implant stability depending on dental implant length and bone density: An in vitro study

Non-invasive objective implant stability measurements are needed to determine the appropriate timing of prosthetic fitting after implant placement. We compared the early implant stability results obtained using resonance frequency analysis (RFA) and damping capacity analysis (DCA) depending on the implant length and bone density. Total 60, 4.0 mm diameter implants of various lengths (7.3 mm, 10 mm, and 13 mm) were used. In Group I, low-density bone was described using 15 PCF (0.24 g/cm3) polyurethane bone blocks, and in Group II, 30 PCF (0.48 g/cm3) polyurethane bone blocks were used to describe medium density bone. RFA was performed using an Osstell® Beacon+; DCA was performed using Anycheck®. Measurements were repeated five times for each implant. Statistical significance was set at P <0.05. In Group I, bone density and primary implant stability were positively correlated, while implant length and primary implant stability were positively correlated. In Group II, the implant stability quotient (ISQ) and implant stability test (IST) values in did not change significantly above a certain length. Primary implant stability was positively correlated with bone density and improved with increasing implant length at low bone densities. Compared with the Osstell® Beacon+, the simplicity of Anycheck® was easy to use and accessible.

Short (≤6 mm) compared with ≥10-mm dental implants in different clinical scenarios: A systematic review of randomized clinical trials with meta-analysis, trial sequential analysis and quality of evidence grading

AIM

To systematically identify, synthesize and critically summarize the available scientific evidence from randomized controlled trials (RCTs) regarding whether short (≤6 mm) perform as well as long (≥10 mm) implants regarding implant survival, marginal bone loss, and biologic and prosthetic complications in different clinical scenarios.

MATERIALS AND METHODS

Cochrane Collaboration's risk of bias tool and the GRADE approach were applied. Results were synthesized using random-effects meta-analyses assessed by trial sequential analyses.

RESULTS

Forty reports on 19 RCTs comprising 2214 (1097 short; 1117 long) implants were included. Moderate/high certainty/quality evidence demonstrated similar 5-year survival rates for ≤6-mm and ≥10-mm implants in non-augmented bone and full-mouth rehabilitation in either jaw, and for 6-mm implants in the maxilla instead of sinus lift. Nevertheless, the evidence for 5-year survival rates remains inconclusive or insufficient for the remaining combinations of implant lengths and clinical scenarios. They include 4-mm and 5-mm implants as alternatives to sinus lift as well as placing all implant lengths ≤6 mm instead of vertical ridge augmentation with long implants. Marginal bone level and short- and long-term biologic or prosthetic complications were similar.

CONCLUSIONS

Based on moderate/high certainty/quality evidence from 5-year RCTs, implants ≤6 mm may be viable alternatives to ≥10-mm implants in either jaw in native bone and full-arch rehabilitation, and 6-mm implants may be used as an alternative to sinus lift.

TRIAL REGISTRATION

PROSPERO ID: CRD42021254365.

Radiographic evaluation of marginal bone levels around implants supporting splinted fixed bridges: A retrospective study on 412 implants

OBJECTIVES

The effect of the implant position within the prosthesis on bone remodeling is scarcely documented so far. Thus, the aim of the present study was to investigate whether central implants may suffer higher peri-implant marginal bone levels (MBL) compared to laterals in case of fixed splinted bridges supported by ≥ three implants.

MATERIALS AND METHODS

Partially edentulous subjects rehabilitated with at least one fixed bridge supported by ≥ three dental implants were enrolled. MBL was assessed radiographically by means of intraoral radiographs acquired with phosphor plates and imported in a dedicated software. MBL was calculated as the distance between the implant platform level and the most coronal visible bone-to-implant contact. A three-level linear mixed effects model was used for investigating the fixed effect of patient-, prosthesis-, and implant-level variables on the MBL.

RESULTS

Overall, 90 patients rehabilitated with 130 splinted fixed bridges supported by 412 implants were included. The median follow-up was 136 months. The mean peri-implant MBL resulted statistically significantly higher at central implants if compared to lateral implants (p < .01). The estimated MBL averages for central and external implants were 1.68 and 1.18 mm, respectively. The prosthesis-level variables suggested that a cement-retained bridge was prone to a significant 0.82 mm higher MBL than a screw-retained one. Implant surface showed an association with MBL changes, although less pronounced than implant retention.

CONCLUSIONS

In case of ≥3 adjacent implants supporting splinted bridges, central implants were more predisposed to MBL compared to laterals. At the prosthesis level, implants supporting cement-retained bridges were statistically more susceptible to MBL compared to screw-retained ones. Surface characteristics can also influence MBL stability at the implant level.

Do dental implants installed in different types of bone (I, II, III, IV) have different success rates? A systematic review and meta-analysis

Purpose

The objective of this systematic review and meta-analysis was to evaluate the survival rate of implants installed in bone type IV (Lekholm and Zarb, 1995) compared to that of implants installed in bone types I, II, and III.

Material and methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) and was registered in the PROSPERO International Database of Systematic Reviews (CRD42021229775). The PubMed/MEDLINE, Scopus, and Cochrane databases were searched through July 2021. The PICO question was: "Dental implants installed in type IV bone have a lower success rate when compared to implants installed in type I bone, II and III?". The established inclusion criteria were: 1) controlled and randomized clinical trials (RCT), 2) prospective and retrospective studies with at least 10 participants with dental implants, and 3) patients with dental implants installed in bone tissue types I, II, III, and IV (Lekholm and Zarb, 1985). The minimum followup duration was 1 year.

Results

After searching the identified databases, 117 articles were selected for full reading and 68 were excluded. Thus, 49 studies were included for qualitative and quantitative analyses. The total number of participants included was 12,056, with a mean age of 41.56 years and 29,905 implants installed. Bone types I, II, and III exhibit a lower implant failure rate when compared to bone type IV.

Conclusion

Dental implants installed in bone types I, II, and III showed significantly higher survival rates than those installed in type IV. The bone type I success rate was not significantly different than that of type II; however, the success rate of bone type I and II was higher than that of type III.

The Use of Splinted Versus Nonsplinted Prosthetic Design in Dental Implants: A Literature Review

The choice of a splinted or nonsplinted implant-supported prosthesis should be based on solid scientific evidence that considers the conditions and needs of each patient. This review elaborates on the factors that directly influence clinical decisions between splinted or nonsplinted dental implants. Digital and manual searches of the published literature were conducted to identify studies that examined splinted prostheses (SPs) and nonsplinted prostheses (NSPs). The search terms used, alone or in combination, were "splinting prosthesis," "nonsplinting prosthesis," "prosthetic design," "stress distribution in dental implant," "implant loading," "implant occlusion," and "crestal bone resorption." Ninety-four studies were selected to compare and address the details emphasized in this study. Thirty-four reported articles were not directly related to restoration design but were reviewed to better understand the influence of mechanical risk factors, finite element analysis limits, and criteria for implant survival and treatment success. There are advantages and disadvantages of splinting implants together. NSPs are the ideal choice because they resemble natural teeth. Splinting a restored implant will cause the implant to appear as part of one unit and is indicated in more compromised situations, unfavorable conditions, or when pontic spaces and cantilevers are needed in implant prostheses.

Biomaterials and Clinical Application of Dental Implants in Relation to Bone Density-A Narrative Review

Titanium has been the material of choice for dental implant fixtures due to its exceptional qualities, such as its excellent balance of rigidity and stiffness. Since zirconia is a soft-tissue-friendly material and caters to esthetic demands, it is an alternative to titanium for use in implants. Nevertheless, bone density plays a vital role in determining the material and design of implants. Compromised bone density leads to both early and late implant failures due to a lack of implant stability. Therefore, this narrative review aims to investigate the influence of implant material/design and surgical technique on bone density from both biomechanical and biological standpoints. Relevant articles were included for analysis. Dental implant materials can be fabricated from titanium, zirconia, and PEEK. In terms of mechanical and biological aspects, titanium is still the gold standard for dental implant materials. Additionally, the macro- and microgeometry of dental implants play a role in determining and planning the appropriate treatment because it can enhance the mechanical stress transmitted to the bone tissue. Under low-density conditions, a conical titanium implant design, longer length, large diameter, reverse buttress with self-tapping, small thread pitch, and deep thread depth are recommended. Implant material, implant design, surgical techniques, and bone density are pivotal factors affecting the success rates of dental implant placement in low-density bone. Further study is required to find the optimal implant material for a clinical setting's bone state.

Effect of short implant crown-to-implant ratio on stress distribution in anisotropic bone with different osseointegration rates

OBJECTIVE

This study aimed to provide evidence for the clinical application of single short implants by establishing an anisotropic, three-dimensional (3D) finite element mandible model and simulating the effect of crown-to-implant ratio (CIR) on biomechanics around short implants with different osseointegration rates.

METHODS

Assuming that the bone is transversely isotropic by finite element method, we created four distinct models of implants for the mandibular first molar. Subsequently, axial and oblique forces were applied to the occlusal surface of these models. Ultimately, the Abaqus 2020 software was employed to compute various mechanical parameters, including the maximum von Mises stress, tensile stress, compressive stress, shear stress, displacement, and strains in the peri-implant bone tissue.

RESULTS

Upon establishing consistent osseointegration rates, the distribution of stress exhibited similarities across models with varying CIRs when subjected to vertical loads. However, when exposed to inclined loads, the maximum von Mises stress within the cortical bone escalated as the CIR heightened. Among both loading scenarios, notable escalation in the maximum von Mises stress occurred in the model featuring a CIR of 2.5 and an osseointegration rate of 25%. Conversely, other models displayed comparable strength. Notably, stress and strain values uniformly increased with augmented osseointegration across all models. Furthermore, an increase in osseointegration rate correlated with reduced maximum displacement for both cortical bone and implants.

CONCLUSIONS

After fixing osseointegration rates, the stress around shorter implants increased as the CIR increased under inclined loads. Thus, the effect of lateral forces should be considered when selecting shorter implants. Moreover, an implant failure risk was present in cases with a CIR ≥ 2.5 and low osseointegration rates. Additionally, the higher the osseointegration rate, the more readily the implant can achieve robust stability.

Clinical effects of conventional and underprepared drilling preparation of the implant site based on bone density: A systematic review and meta-regression

PURPOSE

There is no clinical consensus to determine the right balance between underpreparation and marginal bone level changes. The purpose of this systematic review and meta-regression was to investigate the influence of the type of drilling preparation of the implant site in relation to the bone mineral density on the clinical success, expressed in terms of the MBL and implant failure rate.

STUDY SELECTION

A thorough search was performed using the digital databases MEDLINE PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used were "dental implants", "bone density", and "torque".

RESULTS

The mean bone resorption in the conventional preparation group was -0.43 (± 0.28) mm, whereas it was -0.80 (± 0.37) mm in the underprepared group. For the D1/D2/D3 bone group, the slope was significantly different from zero and linearity; the D4 bone group slope was not significantly different from zero and was almost parallel, although it was significantly different from linearity. The box and whiskers plot shows that the MBL in underprepared sites tended to be significantly higher with a higher variation than that in conventionally prepared sites.

CONCLUSIONS

Within its limits, our meta-regression analysis showed that MBL is influenced by the type of drilling preparation and bone mineral density. In particular, a lower MBL was observed in the D1 bone with conventional preparation than with underpreparation. Moreover, a greater implant-to-osteotomy site mismatch was positively associated with greater MBLs in the bone densities of D1/D2/D3.

Short versus Longer Implants in Sites without the Need for Bone Augmentation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

The present systematic review and meta-analysis aims to analyse the clinical performance of short compared to longer implants inserted in sites without the need for bone augmentation.

METHODS

The protocol of the present PRISMA-driven meta-analysis was registered on PROSPERO (CRD42021264781). Electronic and manual searches were performed up to January 2022. All Randomized Controlled Trials (RCTs) comparing short (≤6 mm) to longer (≥8.5 mm) implants placed in non-atrophic and non-augmented sites were included. The quality of the included studies was assessed using the Cochrane risk of bias tool for randomized clinical trials (RoB 2) and the quality of evidence was determined with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. A meta-analysis was performed on implant survival rate, marginal bone level change (MBLc), and technical and biological complications at the available follow-up time points. The power of the meta-analytic findings was determined by trial sequential analysis (TSA).

RESULTS

From 1485 initial records, 13 articles were finally included. No significant difference was found in the survival rate between short and long implant at any follow-up (moderate quality of evidence). Significantly more bone loss for long implants at 1 and 5 years from implant placement and more technical complications with short implants at 10 years were found. No other significant inter-group differences in terms of MBLc and biological complications were detected.

CONCLUSIONS

Moderate evidence exists suggesting that short implants perform as well as longer ones in the rehabilitation of edentulous sites without the need for bone augmentation. Further long-term, well-designed RCTs, however, are still needed to provide specific evidence-based clinical recommendations for an extended use of short implants in non-atrophic sites.

Single-crown restorations supported by short implants (6 mm) compared with standard-length implants (13 mm) in conjunction with maxillary sinus floor augmentation: a randomized, controlled clinical trial

Background

The purpose of the present study was to test the H0-hypothesis of no difference in the clinical and radiographical treatment outcome of single-crown restorations supported by short implants compared with standard length implants in conjunction with maxillary sinus floor augmentation (MSFA) after 1 year of functional implant loading. Forty patients with partial edentulism in the posterior part of the maxilla were randomly allocated to treatment involving single-crown restorations supported by short implants or standard length implants in conjunction with MSFA. Clinical and radiographical evaluation were used to assess survival of suprastructures and implants, peri-implant marginal bone loss (PIMBL), biological, and mechanical complications.

Results

Both treatment modalities were characterized by 100% survival of suprastructures and implants after 1 year. Mean PIMBL was 0.60 mm with short implants compared with 0.51 mm with standard length implants after 1 year of functional loading. There were no statistically significant differences in survival of suprastructure and implants, PIMBL, and mechanical complications between the two treatment modalities. However, a higher incidence of biological complications was associated with standard length implants in conjunction with MSFA.

Conclusion

Within the limitations of the present study, it can be concluded that single-crown restorations supported by short implants seems to be comparable with standard length implants in conjunction with MSFA. However, long-term studies are needed before final conclusions can be provided about the two treatment modalities.

Trial registration

Clinicaltrials.Gov ID: NCT04518020. Date of registration: August 14, 2020, retrospectively registered.

Impact of peri-implant bone resorption, prosthetic materials, and crown to implant ratio on the stress distribution of short implants: a finite element analysis

The purpose of this study was to determine the effects of prosthetic materials and crown/implant (C/I) ratio on short implants with a marginal bone resorption. Three-dimensional finite element analysis was used to simulate stress distribution under static loading in non-resorption and resorption scenarios (3-mm vertical bone loss) in implants restored with single crowns and C/I ratios of 1:1, 1.5:1, and 2:1 were evaluated. Different crown materials were used: porcelain-fused to metal, porcelain-fused to zirconia, monolithic zirconia, and zirconia-based crown veneered with indirect composite resin. The C/I ratio, the peri-implant bone resorption, and the loading conditions were the key factors affecting the generated stress in short implants. In non-resorption models, von Mises stress ranged between 50 and 105 MPa whereas in resorption models, the values ranged from 168 to 322 MPa, both increasing with the higher C/I ratio under oblique forces. Under axial loading, the C/I ratio did not influence the stress values as the presence of resorption was the only parameter increasing, 57 MPa for the non-resorption models and 101 MPa for the resorption models, respectively. Preference of a prosthetic material was ineffective on the distribution of stress in the bone and implant structure under static loading in any models. The peri-implant bone resorption and a higher C/I ratio in short implants increase the stress values under both axial and oblique forces, whereas the crown material does not influence stress distribution in the surrounding bone and implant structure.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

Influence of crown-to-implant ratio and different prosthetic designs on the clinical conditions of short implants in posterior regions: A 4-year retrospective clinical and radiographic study

BACKGROUND

Short implants (intra-bony length ≤ 8 mm) are generally considered as an alternative to bone augmentation in challenging situations; however, clinical evidence from large-scale studies with long follow-up regarding the application of short implants remains deficient.

PURPOSE

The present study aimed to assess the mid-term clinical outcomes of short implants supporting fixed prostheses in the posterior region, and to investigate the effects of the crown-to-implant ratio (C/I), and other patient-, implant-, prosthesis-relevant factors on the clinical conditions around short implants.

MATERIALS AND METHODS

180 Thommen short implants in 130 partially edentulous patients were enrolled in the study after 3 to 7 (mean 4.2) years of follow-up. Potential risk factors (patient sex and age, implant diameter and location, splinted vs single-tooth restorations, retention mode, anatomical and clinical C/I ratios) were evaluated according to the following outcomes: Implant survival, marginal bone loss (MBL), and mechanical and biological complications.

RESULTS

In total, four implants in four patients failed as a result of peri-implantitis. The cumulative survival rate was 97.8% for implant-based analysis. The peri-implant MBL around 180 short implants was 0.90 ± 0.78 mm. The mean clinical C/I ratio was 1.16 ± 0.36. Correlation analysis revealed that the influence of the clinical C/I ratio and patient age were significant for MBL (P < .05), whereas other potential risk factors showed no significant association with the outcome. Among 180 short implants, 24 cases (13.3%) had biological complications and 32 cases (17.8%) had mechanical complications, respectively. Peri-implant MBL and complication rates around splinted and non-splinted implants were not statistically different.

CONCLUSION

Within the limitations of this study, short implants supporting fixed prostheses in the posterior region achieved predictable clinical outcomes over a 3 to 7 year period. Within the range of 0.47 to 3.01, the higher the C/I ratio, the less the peri-implant MBL.

Retrospective clinical analysis of risk factors associated with failed short implants

BACKGROUND

With advanced technology, short implants are more commonly used and have proven to have a relatively reliable curable efficacy. A consensus has not been reached regarding potential risk factors related to the loss of short implants.

PURPOSE

This large-sample retrospective study concentrated not only on patient characteristics and medical procedures but also on the features of implants in order to uncover the risk factors associated with short implants.

METHODS

Between 2014 and 2017, a total of 7001 implants were inserted at Nanjing Stomatological Hospital, Medical School of Nanjing University. Among the all, 1236 short implants were included after being evaluated according to the inclusion and exclusion criteria. In organizing the detailed information, seven variables including bone grafting procedure, age, gender, diameter of the implant, implant position, surface treatment, and definitive restorations were taken into consideration. The χ² test, Kaplan-Meier test, logistic regression, and multifactorial Cox regression analysis were employed to explore the risk factors.

RESULTS

The cumulative survival rate of short implants was 96.36%, slightly lower than that of the standard implants (98.16%, P < .001). Most of the short implants (84.44%) were lost at the early stage, mainly because of infection. Based on the results, male gender, implants treated by titanium anodizing and single-crown restoration increased the loss rate of short implants. Comparison of the short implants inserted into the maxillary and mandibular posterior area alone showed that the maxillary molar area was a risk factor for prognosis.

CONCLUSIONS

Male gender, TA surface treatment, and the presence of a single crown were associated with an increasing rate of short implants loss. Examination of the implant location focused on the posterior area revealed the maxillary posterior area to be a risk factor.

Principles of biomechanics in oral implantology

Background and aims

The principles of biomechanics comprise all the interactions between the body (tissues) and the forces acting upon it (directly or via different medical devices). Besides the mechanical aspects, the tissues response is also studied. Understanding and applying these principles is vital for the researchers in the field of oral implantology, but they must be equally known by the practitioners. From the planning stages to the final prosthetic restoration, they are involved in each and every aspect. Ignoring them inevitably leads to failure.

Methods

The first part of this paper includes a review of our current research in oral implantology (mechanical, digital and biological testing), while the second part includes a review of the available literature on certain biomechanical aspects and their implications in everyday practice.

Results

Our research opens new study directions and provides increased chances of success for dental implant therapy. The practical aspects of our findings, combined with the available literature (from the basic principles described more than 40 years ago to the most recent studies and technologies) can serve as a guide to practitioners for increasing their success rate.

Conclusion

While no therapy is without failure risk, a good understanding of the biomechanics involved in oral implantology can lead to higher success rates in implant supported prosthetic restorations.

Descriptive retrospective study analyzing relevant factors related to dental implant failure

Background

The objective of this retrospective descriptive study was to analyze the characteristics of incident reports provided by dentists while using a specific brand of dental implants.

Material and Methods

The study was carried out in collaboration with Oxtein Iberia S.L.®, with the company providing access to the incident database in order to evaluate the characteristics of incidents from January 2014 to December 2017 (a total of 917 over four years). The data sheet recorded different variables during each of the stages of implant treatment, from initial implant placement to subsequent prosthetic rehabilitation. These variables included age, sex, systemic pathologies, smoking habits, bone quality, implant type, prosthesis type, and type of load applied, among others. SPSS Statistics was used to perform statistical analysis of the qualitative variables (univariate logistic regressions, χ2 test, Haberman's adjusted standardized residuals).

Results

The total study sample consisted of 44,415 implants shipped from Oxtein® warehouses on the dates indicated, of which 917 implants (2.1%) were flagged due to reports of lack of primary stability, failed osseointegration, or implant failure within one year of placement. When analyzing incident reports, it was observed that 61.6% of incidents occurred in male patients, compared to 38.4% in female patients. The average age of patients in the reported cases was 56.12 ± 12.15 years. A statistically significant correlation was discovered between incidents of implant failure and tobacco use, diabetes, heart disease, poor oral hygiene, previous infection, poor bone quality, and bruxism (p < 0.05). A (statistically significant) higher rate of incidents was also observed in tapered, internal connection, Grade IV titanium, narrow, and short implants.

Conclusions

Analysis of these implants reveals a higher rate of complication in short, tapered, internal connection and narrow-diameter implants. These data can help and encourage clinicians to use the utmost surgical precautions when placing these implants.

Key words:Pharmacovigilance, Dental implant, Dental implant failure.

The Effect of the Length and Distribution of Implants for Fixed Prosthetic Reconstructions in the Atrophic Posterior Maxilla: A Finite Element Analysis

In this study, different prosthetic designs that could be applied instead of advanced surgical techniques in atrophic maxilla were evaluated with finite element analysis. Atrophic posterior maxilla was modeled using computer tomography images and four models were prepared as follows: Model 1 (M1), two implants supporting a three-unit distal cantilever prosthesis; Model 2 (M2), two implants supporting a three-unit conventional fixed partial denture; Model 3 (M3), three implants supporting three connected crowns; and Model 4 (M4), two implants supporting two connected crowns. Implants 4 mm in width and 8 mm or 13 mm in length were used. A linear three-dimensional finite element programme was used for analysis. The maximum principle stress (tensile) and minimum principle stress (compressive) were used to display stress in cortical and cancellous bones. The von Mises criteria were used to evaluate the stress on the implants. M1 was found to be the most risky model. The short dental arch case (M4) revealed the lowest stresses among the models but is not recommended when one more implant can be placed because of the bending forces that could occur at the mesial implant. In M2 and M3, the distal implants were placed bicortically between the crestal and sinus cortical plates, causing a fall of the stresses because of the bicortical stability of these implants.

Effect of Implant-Abutment Connection Type on Bone Around Dental Implants in Long-Term Observation: Internal Cone Versus Internal Hex

PURPOSE

The purpose of this study was to evaluate the influence of the implant-abutment connection type on the bone level around dental implants in long-term observation and the survival rate for the different types of implant-abutment connections.

MATERIALS AND METHODS

Two groups of implants made of titanium grade 23 alloy and with sandblasted and acid-etched (SLA) surface were included in the study: (a) the internal hex implant-abutment connection group (480 SPI dental implants; Alpha-Bio Tec, Petach Tikwa, Israel, 184 patients) and (b) the internal cone implant-abutment connection group (60 C1 dental implants; MIS Implant Technologies, Shlomi, Israel, 34 patients). Certain inclusion and exclusion criteria were applied. Marginal bone loss (MBL) around the dental implants was measured in intraoral radiographs taken with parallel technique with a film holder and by bite recording index. X-rays were performed at the moment of functional loading, and at 12, 24, 36, and 60 months after loading. The digital analysis was conducted using Dental Studio 2.0 computer software.

RESULTS

Average MBL was significantly lower in the conical connection compared with internal hex group-0.68 ± 0.59 versus 0.99 ± 0.89 mm (12 months), 0.78 ± 0.80 versus 1.12 ± 1.00 mm (24 months), 0.83 ± 0.87 versus 1.22 ± 1.03 mm (36 months), and 0.96 ± 1.02 versus 1.30 ± 1.15 mm (60 months after loading). Both groups of implants achieved a 100% survival rate.

CONCLUSION

The internal cone connection reduced bone resorption compared with the internal hex. Both groups of implants had a 100% survival rate.

Meta-analysis of randomized clinical trials comparing clinical and patient-reported outcomes between extra-short (≤6 mm) and longer (≥10 mm) implants

AIM

To compare the clinical outcomes of ≤6 mm extra-short implants (test group) versus ≥10 mm long implants (control group), with and without bone augmentation procedures.

MATERIALS AND METHODS

A systemic literature search of randomized clinical trials was performed using the PubMed (MEDLINE) and EMBASE databases. A quantitative meta-analysis was conducted to compare all the outcome variables. Meta-regression analysis determined the effect of bone augmentation procedures and the influence of other clinical covariates on the results.

RESULTS

Eighteen studies comprising 1,612 implants (793 extra-short and 820 long implants) were selected for the meta-analysis. No statistically significant difference in the survival rate was observed at 1 and 3 years (p > 0.05). Extra-short implants displayed less marginal bone loss (MBL) from both implant placement time points (1 and 3 years) and prosthetic placement (1 year), as well as less biological complications, surgical time and treatment cost (p < 0.05). Contrarily, a statistically significant small number of prosthetic complications were reported with long implants (p < 0.05).

CONCLUSIONS

Placement of extra-short implants (≤6 mm) presented as an equivalent option in the treatment of patients with an atrophic posterior arch up to 3-year follow-up. However, the long-term effectiveness of extra-short dental implants remains to be further studied.

A prospective study on ultra-wide diameter dental implants for immediate molar replacement

BACKGROUND

Although wide diameter implants are well documented, little is known about ultra-wide diameter implants (>6 mm). This study evaluates the clinical outcome of ultra-wide diameter implants, placed in molar extraction sockets.

MATERIALS AND METHODS

Ultra-wide diameter implants (7-9 mm) were placed immediately after molar extraction in a 1-stage protocol, without raising a flap or using any bone grafts. After 4 months, the implant was loaded with a single screw-retained crown. Bone loss was evaluated using peri-apical radiographs. Plaque and bleeding were recorded. Crown and papilla dimensions were measured and compared with the contra-lateral tooth.

RESULTS

Fifty-one patients (36 male and 15 female), mean ages 61 years old, were treated with 26 implants in the maxilla and 25 implants in the mandible. The majority had a thick (#19) or medium (#31) biotype. After a mean-follow-up period of 23 months, the mean bone level was located 1.16 mm apical of the implant-abutment junction (SD 0.42, range 0.00-2.45) while the actual bone remodeling associated with socket healing resulted in a mean coronal movement of the bone level of 0.15 mm. The mean insertion torque was 116 Ncm (SD 53, range 10-250). There were no differences in papilla height (P = .55), crown length (P = .32), zenith (P = .84), and bucco-palatal dimensions (P = .38). There was a significant difference in the mesio-distal dimension (P = .01). Mean probing depth was 2.59 mm at the implant and 2.23 mm at the contra-lateral tooth (P = .001). There was significantly more plaque at the tooth compared to the implant (P = .01), but there was no significant difference in terms of bleeding on probing (P = .08). Patient satisfaction was high with 72.5% of the patients experiencing no problems at all.

CONCLUSIONS

Ultra-wide diameter implants have a predictable outcome, demonstrating very little bone loss. Papilla and crown dimensions were comparable to the contra-lateral natural tooth.

Do short implants have similar survival rates compared to standard implants in posterior single crown?: A systematic review and meta-analysis

BACKGROUND

Short implants have been presented as an option for posterior rehabilitation in cases of poor bone height.

PURPOSE

To compare the survival rate of short implants and standard implants when used in posterior single crowns, in addition to reporting marginal bone loss, prosthetic failures, and surgical complications.

MATERIALS AND METHODS

Electronic search (PubMed, LILACS, Cochrane Library, Scopus, and Web of Science) and hand search were performed to identify all randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated both short and standard implants in posterior single crowns.

RESULTS

Out of 345 articles identified by both electronic and hand search, four studies were selected (one CCT and three RCTs). The meta-analysis for the survival rate showed that there was no significant difference between the short implants and the standard ones (P = 1.00; RR:1.00; CI:0.97-1.03) performed with three RCTs for a one-year follow-up. The mean marginal bone loss ranged from 0.1 mm to 0.54 mm. Only one study reported the presence of prosthetic failures and surgical complications.

CONCLUSIONS

The survival rate of short implants was similar to the standard ones in posterior single crowns, for the one-year follow-up period. They also presented low surgical complications, prosthetic failures and marginal bone loss, being a predictable treatment for single rehabilitation in posterior tooth loss.