Randomized controlled clinical trial comparing two dental implants with different neck configurations

Comparison of external, internal flat-to-flat, and conical implant abutment connections for implant-supported prostheses: A systematic review and network meta-analysis of randomized clinical trials

STATEMENT OF PROBLEM

The implant abutment connection interface has been considered one of the major factors affecting the outcome of implant therapy. However, drawbacks of traditional meta-analyses are the inability to compare more than 2 treatments at a time, which complicates the decision-making process for dental clinicians, and the lack of a network meta-analysis.

PURPOSE

The purpose of this network meta-analysis was to assess whether the implant abutment connection influences the outcome of implant-supported prostheses.

MATERIAL AND METHODS

An electronic search was undertaken to identify all randomized clinical trials comparing the effect of at least 2 different implant abutment connection designs published from 2009 up to May 2020. Outcome variables were implant survival rate, peri-implant marginal bone loss, and biologic and prosthetic complication rates at 12 months after prosthetic loading. Relevant information was extracted, and quality and risk of bias assessed. Pairwise meta-analyses and network meta-analyses based on a multivariate random-effects meta-regression were performed to assess the comparisons (α=.05 for all analyses).

RESULTS

For peri-implant marginal bone loss and prosthetic complications, conical interfaces were determined to be the most effective, with significant differences when compared with external hexagonal connections (P=.011 and P=.038, respectively). No significant differences were found among the implant abutment connections in terms of survival and biologic complications (P>.05 in all direct, indirect, and mixed comparisons).

CONCLUSIONS

After 1 year of loading, conical connections showed lower marginal bone loss and fewer prosthetic complications than external hexagonal connections. However, the implant abutment connection design had no influence on the implant survival and biologic complication rates.

The effect of a convergent transmucosal neck on soft tissues and radiographic outcomes: a 1-year follow-up randomized controlled trial

PURPOSE

The aim of this randomized controlled clinical trial was to evaluate peri-implant marginal bone levels (MBLs) and soft tissue dimension changes 1 year after loading. Patients in the control group received bone-level implants, whereas in the test group, tissue-level implants with a convergent transmucosal neck were used.

MATERIAL AND METHODS

MBLs were calculated by measuring the distance from the implant shoulder to the first visible bone-to-implant contact using standardized periapical digital radiographs. Baseline (day of loading) and follow-up digital models obtained with an intraoral scanner were used to quantify the changes in the peri-implant soft tissue dimensions with a best-fit algorithm.

RESULTS

The difference between final and baseline MBLs showed a mean bone loss of 0.16 ± 0.01 mm in the test group (n = 15) and 0.45 ± 0.09 mm in the control group (n = 14) (p > 0.05). Soft tissue contour at the level of the gingival margin (GM) increased by 1.96 ± 2.69 mm in the test group and 0.65 ± 0.42 mm in the control group (p = 0.167). Both groups showed a coronal displacement of the gingival margin with no significant differences among them.

CONCLUSIONS

The present study demonstrated peri-implant hard and soft tissues stability at both implant designs with no significant differences 12 months after loading.

CLINICAL RELEVANCE

There is still insufficient scientific evidence to demonstrate the role and advantages of the convergent transmucosal neck on the behavior of the peri-implant soft and hard tissues stability compared to a straight neck in bone-level implants 12 months after loading.

Is the clinical performance of internal conical connection better than internal non-conical connection for implant-supported restorations? A systematic review with meta-analysis of randomized controlled trials

PURPOSE

To evaluate bone loss, prosthodontics and biological complications, and implant survival rates of internal conical connections (ICC) compared with internal non-conical connection (INCC) implants.

METHODS

The systematic review was registered on PROSPERO (CRD42021237170). Meta-analysis was performed using standardized mean difference (SMD) for bone loss and risk ratio (RR) for implant survival and complication rates. Risk of bias analysis was evaluated using RoB 2.0, whereas the GRADE tool was used to evaluate the certainty of evidence. A systematic search of the PubMed, Web of Science, Embase, Cochrane, and ProQuest databases was performed independently by two reviewers for articles published up to March 2022. The search criteria had no language or publication date restrictions. Handsearching analysis was performed in the reference list of potential articles.

RESULTS

Twelve randomized clinical trials, including 678 patients and 1006 implants (ICC [n = 476]; INCC [n = 530]), were included. Meta-analysis revealed that ICC demonstrated a lower risk for marginal bone loss (SMD: -0.80 mm; p = 0.004) and prosthodontics complications (RR: 0.16; p = 0.01) than INCC. However, both internal connections demonstrated no significant difference in implant survival rates (RR: 0.54; p = 0.10) and biological complications (RR: 0.90; p = 0.82). The overall risk of bias revealed some concerns and a low risk of bias for most of the included studies. However, the certainty of evidence of outcomes was considered low to moderate.

CONCLUSION

ICC may be considered a more favorable treatment option than INCC owing to greater preservation of peri-implant bone tissue and a lower probability of prosthodontics complications. However, well-conducted studies with long-term follow-up are warranted.

Bone-level changes around implants with 1- or 3-mm-high abutments and their relation to crestal mucosal thickness: A 1-year randomized clinical trial

AIM

To evaluate 1-year bone-level changes around subcrestal platform-switching implants with 1 or 3 mm definitive abutments. The influence of mucosal thickness on bone-level alterations was further analysed.

MATERIALS AND METHODS

Implants were placed in the posterior sextants and positioned 1.5 mm subcrestally with an abutment of 1 or 3 mm height. Final restorations were delivered after 16 weeks. Radiographic measurements of inter-proximal bone level were the primary outcome and were adjusted by vertical mucosal thickness. Peri-implant clinical conditions and resonance frequency analysis were also compared.

RESULTS

A total of 65 subjects with 99 implants were analysed. The overall 1-year implant survival rate between the 1- and 3-mm groups was 96.4% and 94.4%, respectively. Statistically significant lower inter-proximal marginal bone-level changes were observed in the 3-mm group (1 mm: -0.17 ± 0.02 mm at mesial and -0.21 ± 0.02 mm distal; 3 mm: -0.03 ± 0.02 mm at mesial and -0.03 ± 0.02 mm and distal; mesial: p = .001; distal: p < .001). Initial vertical mucosal thickness was not correlated with inter-proximal marginal bone loss.

CONCLUSIONS

Subcrestal implants with 3-mm abutment were associated with minimal inter-proximal bone loss. Independent of the abutment height, crestal mucosal thickness was not correlated with bone loss.

Maryland-bridge application as a suitable technique to preserve marginal bone level of not-submerged supracrestal implants

BACKGROUND

One to 6 months after implant placement is a critical time/period responsible for crestal bone loss that may affect implant osseointegration. The study aims to explore the effectiveness of provisional adhesive Maryland-bridge (AMB) applied to prevent marginal bone level (MBL) around implants placed in edentulous crestal bone in posterior area during osseointegration period.

METHODS

Healthy, non-smoker patients (N.=18) were included in the study. Titanium implants were placed nonsubmerged (i.e. tissue-level) with cover screws at gingival level in edentulous crestal bone with flapless technique. Nine patients randomly received an AMB, while 9 patients did not receive any AMB. Each AMB remained in place for 3 months and removed before impression. After 3 months abutments were applied, and provisional resin crowns cemented and definitive metal-ceramic crowns were cemented after 2-3 months. Periapical Rx were taken using paralleling technique before and after implant insertion, at 1, 3 months (pre-loading time) and after 6 months (post-loading time). MBL was evaluated in double-blind on scanned periapical radiographs and assessed at mesial and distal side of implants (M-MBL and D-MBL). Area of bone loss on mesial and distal side of implants (Area-M and Area-D) and Cervical Enamel Junction migration of mesial and distal adjacent teeth were also measured (CEJ-M and CEJ-D). Linear regression models were fitted to evaluate the existence of any significant difference.

RESULTS

Two drop-out was observed in AMB group. A total of 16 patients completed the study. After 6 months, all implants were safe and free from complications. AMB group showed the most stable MBL at 1-6 months, statistically different from non-AMB and resulted in a reduced crestal bone loss from baseline compared to Non AMB group. Area-M and Area-D were not statistically different between the groups. CEJ-M and CEJ-D were stable in both groups.

CONCLUSIONS

The use of Adhesive Maryland Bridge to protect non-submerged post-extractive implants is a safe procedure that prevents bone loss around implants and preserve the 3D architecture of crestal bone ridge.

Clinical and radiographic performance of one-piece and two-piece implant:a systematic review and meta-analysis

PURPOSE

The aim of this system review was to evaluate clinical and radiographic performance of one-piece implant (OPI) and two-piece implant (TPI).

METHODS

Electronic database searches were performed in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and OpenGrey databases up to May 2019. Two authors individually screened the related literatures according to the inclusion and exclusion criteria. Main clinical outcomes included failure and complication rates. Radiographic outcomes were peri-implant bone loss between baseline and last available follow-up.

RESULTS

Finally, 11 articles reporting 10 different studies were included in this review. No statistically significant difference (P = 0.22) in risk of failure was found between the two types of implants (RR: 0.49, 95% CI: 0.16-1.53). Peri-implantitis accounted for most failures and complications and there was no statistically significant difference in risk of peri-implantitis no matter after 1 year follow-up (RR: 1.15, 95% CI: 0.37-3.53, P = 0.81) or at 2-3 years (RR: 1.95, 95% CI: 0.23-16.63, P = 0.54). With regard to the marginal bone loss (MBL) around implants, subgroup meta-analysis by platform switching versus platform matching showed a significant MBL-reducing effect for TPI when compared to OPI (WMD: 0.21mm, 95% CI: 0.07-0.36mm, P = 0.004) in the platform-switching subgroup, while no significant difference in MBL was observed between the two groups in the platform-matching subgroup (P = 0.67).

CONCLUSIONS

The results of this review suggested that OPI and TPI showed similar short-term survival rates and incidences of complications. Nevertheless, TPI with platform switching may be a better option to reduce peri-implant bone loss.

The Why, What, How and What if-The method to present your research and clinical cases

BACKGROUND

During the fourth Summer Camp (SC) held by the European Association of Osseointegration (EAO), 20 junior representatives from various European and non-European universities and associations were selected to partake in oral presentation and communication skill development.

AIMS

The aim of the EAO Summer Camp (EAO SC) was to identify new methods of enhancing participants' abilities to engage, influence and lead in a professional environment, on both a clinical and scientific level.

MATERIALS AND METHODS

Four different groups were assigned to discuss one of two topics: (1) an Implant Register and (2) Digital Dentistry. The method that was used during the EAO SC, for training presentation skills, was the 4MAT learning model. The 4MAT learning model is a framework for creating an engaged, dynamic and more involved style of training by accurately visualizing the learning process that each learner goes through.

RESULTS AND CONCLUSIONS

All four groups, including each participant, presented outcomes in the format of 4MAT learning model answering four key questions, the Why, the What, the How and the What if. After the event, each group prepared a written summary of the thought processes. The outcome of the summer camp, for the chosen participants, was gaining skills to engage and influence in a professional environment, both clinically and scientifically. It was also expected from participants to share gained knowledge in their own respective environments after the EAO Summer Camp had ended. In conclusion, most of participants gained a valuable insight into presentation skills and also demonstrated their enthusiasm by presenting their experience at universities, institutes and clinics.

Effect of Different Implant Designs on Strain and Stress Distribution under Non-Axial Loading: A Three-Dimensional Finite Element Analysis

Implant design evolved alongside the development of implant therapy. The purpose of this finite element analysis (FEA) study was to analyze the influence of different implant designs on the stress and strain distribution to the implants and surrounding bone. Three implant designs with the same length and diameter were used. The three-dimensional geometry of the bone was simulated with a cortical bone of three different thicknesses and two medullar bone densities: low density (150 Hounsfield units) and high density (850 Hounsfield units). A 30° oblique load of 150 N was applied to the implant restoration. Displacement and stress (von Mises) results were obtained for bone and dental implants. The strain and stress distributions to the bone were higher for the tissue-level implant for all types of bone. The maximum principal strain and stress decreased with an increase in cortical bone thickness for both cancellous bone densities. The distribution of the load was concentrated at the coronal portion of the bone and implants. All implants showed a good distribution of forces for non-axial loads, with higher forces concentrated at the crestal region of the bone–implant interface. Decrease in medullar bone density negatively affects the strain and stress produced by the implants.

Marginal bone loss around bone-level and tissue-level implants: A systematic review and meta-analysis

PURPOSE

To review the scientific evidence regarding the marginal bone loss around the tissue-level and bone-level implants.

METHODS

MEDLINE-PubMed and EMBASE databases were searched for the relevant English articles (up to February 2019) assessing the marginal bone loss (MBL) as the primary outcome. To be selected, studies were supposed to directly mention "tissue-level" and "bone-level" implants or implants with and without a smooth neck. Relevant data were extracted and meta-analysis was performed to evaluate the effect of implant neck design.

RESULTS

A total of 19 studies (10 clinical, and 9 RCT studies) were included for qualitative analysis. There was a vast heterogeneity between studies in terms of implant designs and study protocol. Out of 19 articles included, 11 studies reached to a statistically significant difference in MBL between the groups; however, the differences were not found to be clinically relevant. Bone-level implants with platform-switched abutments in most of the cases showed better marginal bone stability compared to tissue-level implants or bone-level implants with matching abutments. Seven RCTs with 12 months follow-up data were selected for meta-analysis (I²=93%; heterogeneous), and the results showed less MBL around bone-level implants compared to tissue-level group (WMD=-0.21mm; 95% CI -0.42, 0.00; P=0.06).

CONCLUSION

The available data regarding comparison of MBL around bone-level and tissue-level implants are heterogeneous. Bone-level implants with platform switching may better preserve crestal bone.

Clinical and patient-reported outcome of implant restorations with internal conical connection in daily dental practices: prospective observational multicenter trial with up to 7-year follow-up

Background

The interpretation of the results of randomized clinical trials is often questioned in relation with daily circumstances in practices. This prospective observational multicenter study was instigated to reflect the need for information in real-life situations with dental implants with internal conical implant-abutment connection (Conelog implant system). The implants were followed up at least 5-year post-loading; survival analysis (Kaplan-Meier), changes of soft tissue, and bone level over time, as well as patient satisfaction were evaluated.

Results

In total, 130 dental implants were placed in 94 patients (64 female, 30 male). Mean age of patients was 50.4 ± 13.7. At 5-year post-loading, 104 implants in 76 patients were available for evaluation. The cumulative implant survival rate was 96.6%. After an initial bone remodeling process post-surgery (bone loss of − 0.52 ± 0.55 mm), the bone level change remained clinically stable from loading to 5-year post-loading (− 0.09 ± 0.43 mm). Patient satisfaction surveyed by questionnaire (comfort, ability to chew and taste, esthetics, general satisfaction) steadily increased towards the end. At the last study follow-up, all the patients rated their general satisfaction as either very satisfied (87.5%) or satisfied (12.5%).

Conclusion

The study implants have shown to be highly effective with reliable peri-implant tissue stability over the 5 to 7 years of observation for both single tooth restorations and fixed partial dentures while used in standard conditions in daily dental practice. The results obtained are comparable with those obtained in controlled clinical trials.

A clinical comparison of 1-piece versus 2-piece implants: A systematic review and meta-analysis

STATEMENT OF PROBLEM

One-step dental implant surgery with a 1-piece implant has been introduced with the aim of simplifying and increasing the effectiveness of treatment and providing greater comfort for the patient. Whether these goals have been met compared with conventional 2-piece implants remains unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the use of 1-piece versus 2-piece implants in terms of marginal bone loss and implant survival rate.

MATERIAL AND METHODS

This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was recorded in the International prospective register of systematic reviews (PROSPERO) database (CRD 42018095721). A literature search was conducted in the PubMed/MEDLINE, Web of Science, and Cochrane Library databases for articles published up to May 2018. The population, intervention, comparison, outcome (PICO) question was, "Do patients who received 1-piece implants show similar marginal bone loss, survival rates, and complications as those who receive 2-piece implants?"

RESULTS

The meta-analysis was based on the Mantel-Haenszel and inverse variance methods. Implant survival rate was analyzed by using a dichotomous outcome, measured according to risk ratio (RR) and marginal bone loss by continuously evaluating the outcomes according to the mean difference (MD), both with a corresponding 95% confidence interval (CI). Five studies, including 270 participants with a mean age of 54.70 years and receiving 434 dental implants, were included. The mean follow-up period was 4 years. Meta-analysis did not reveal a significant difference in relation to implant survival rate (P=.85; RR: -0.89; CI: -0.27 to 2.98), as well as to marginal bone loss (P=.85; MD: -0.43; CI: -0.43 to -0.52).

CONCLUSIONS

One- and 2-piece implants demonstrated effectiveness in the rehabilitation of patients requiring dental implants.

Influence of Biologically Oriented Preparation Technique on Peri-Implant Tissues; Prospective Randomized Clinical Trial with Three-Year Follow-Up. Part I: Hard Tissues

PURPOSE

The objective of this prospective randomized clinical trial (RCT) was to analyze and compare the clinical behavior of three types of prosthesis supported by single implants in the posterior region after three years functional loading.

MATERIALS AND METHODS

Seventy-five implants were divided into three groups according to the type of prosthetic restoration: screw-retained crown (Group GS); cemented crown without finishing line (biologically oriented preparation technique) (Group GBOPT); and conventional cemented crown with finishing line (Group GCC). The clinical behavior of each restoration type was analyzed after 3 years functional loading by analyzing radiographic peri-implant bone loss.

RESULTS

GBOPT obtained the least bone loss (p < 0.01) in comparison with GS and GCC.

CONCLUSIONS

Bone loss around implants is related to the type of prosthetic restoration it supports, whereby cemented BOPT crowns present less bone loss.

Titanium dental implants with different collar design and surface modifications: A systematic review on survival rates and marginal bone levels

AIM

The aim of this study was to compare clinical and radiographic outcomes of dental implants with different neck characteristics.

METHODS

A protocol-oriented search aimed at the question: "In patients subjected to tooth replacement with screw-type dental implants does the modification of the implant neck macro- or microgeometry contribute to the improvement of survival rates and maintenance of the peri-implant marginal bone levels?" Primary outcomes were survival and marginal bone level (MBL) changes evaluated on randomized controlled trials with >10 participants and follow-up >1 year. Risk of bias was evaluated using the Cochrane Collaboration's tool. The review follows the PRISMA statement.

RESULTS

Forty-three studies compared: (a) One- versus two-piece implants (N = 7); (b) Two-piece implants with different neck characteristics (machined and rough collars, microthreads, LASER microtexturing) (N = 21); (c) Two-piece implants with macrogeometry modifications (tapering, back-tapering, and scalloping) (N = 6). One- and two-piece implants showed similar survival (RR = 0.45, 95% CI: [0.12, 1.66], p = 0.23) and MBL changes (WMD = 0.09 mm, 95% CI: [-0.27, 0.45], p = 0.64) at 1-year post-loading. Machined collar implants have higher risk of early failure than rough collar implants (RR = 3.96, 95% CI: [1.12, 13.93], p = 0.03) and 0.43 mm higher bone resorption (95% CI: [0.0, 0.86], p = 0.05). Microthreads (WMD = 0.07 mm, 95% CI: [-0.01, 0.15], p = 0.10) and LASER microtexturing (WMD = 0.15 mm, 95% CI: [-0.35, 0.65], p = 0.56) do not reduce bone resorption. Scalloped implants have 1.26 mm higher resorption (95% CI: [0.72, 2.00], p < 0.001).

CONCLUSIONS

One- and two-piece implants have similar survival and MBL changes. Rough collar implants have lower MBL changes than machined collar implants. Additional modifications to rough collars are irrelevant.