Bimaxillary fixed implant-supported zirconium oxide prosthesis therapy of an adolescent patient with non-syndromic oligodontia and two WNT10 variants: a case report

Introduction and importance

Oligodontia is a rare genetic condition characterized by more than six congenitally missing teeth, either as an isolated non-syndromic condition or in association with other genetic syndromes. The impact of WNT10A variants on dental development increases with the presence of the c.321C>A variant and the number of missing teeth.

Case presentation

A 21-year-old man with non-syndromic oligodontia was diagnosed at 15 years of age with misaligned teeth, speech problems, and the absence of 24 permanent teeth. Interdisciplinary collaboration between specialists was initiated to enable comprehensive treatment. DNA analysis confirmed that the patient was a carrier of the known pathogenic WNT10A variant c321C>A and WNT10A variant c.113G>T of unknown clinical significance.

Clinical discussion

Dental implants are a common treatment; however, bone development challenges in adolescent patients with non-syndromic oligodontia necessitate careful planning to ensure implant success. Many WNT variants play crucial roles in tooth development and are directly involved in non-syndromic oligodontia, especially the WNT10 variant c.321C>A.

Conclusion

A full-arch implant-supported monolithic zirconia screw-retained fixed prosthesis is a viable treatment option for young adults with non-syndromic oligodontia. Further studies are needed to clarify the possible amplifying effect of the WNT10A variants c321C>A and c.113G>T on the pathogenic phenotype of non-syndromic oligodontia.

Screw-retrievable cement-retained implant restorations: A scoping review of fracture strength and clinical performance

BACKGROUND

The screw-retrievable cement-retained (SRCR) design combines the benefits of both screwand cement-retained implant-supported restorations. This concept has sparked interest in implant dentistry. However, there is a lack of research on fracture behaviors and clinical performance of such restorations.

OBJECTIVES

The aim of the present article was to review the current literature on the fracture loads and fracture modes of SRCR implant restorations - in vitro studies, and also studies demonstrating the clinical performance of such design.

MATERIAL AND METHODS

A literature search was conducted from January 2000 to June 2022, using 6 databases to identify studies on fracture load and clinical performance that fulfilled the eligibility criteria. Thirty-eight studies met the inclusion criteria (22 in vitro and16 in vivo). The in vivo studies comprised case reports/series/letters (9), clinical techniques (2), retrospective/prospective studies (3), and randomized controlled trials (RCTs) (2).

RESULTS

The reviewed articles reported the effects of the SRCR design on the fracture risk if screw access channels were filled or unfilled, with regard to their diameter, and the preparation before or after glazing. The effect of the type of material used in the construction on the fracture modes SRCR restorations was also reported. The long-term clinical data was mainly retrospective and referred to metal-ceramic constructions. Limited long-term clinical data was available for all-ceramic materials and high-performance polymers (HPPs).

CONCLUSIONS

Screw-retrievable cement-retained implant restorations appear to have potential in the monolithic design. If the SRCR construction is metal-ceramic or made of a veneered material, special design and abutment selection should be considered. High-performance polymers may be recommended as a substitute for posterior implant restoration.

Technique for cementing screwmentable implant crowns to prevent misalignment

The purpose of this article is to describe a technique to accurately cement implant crowns on an abutment extraorally and prevent misalignment that might change the desired position of the crown on the abutment when delivered. An implant-retained crown was tried-in and occlusal and interproximal contacts were adjusted for delivery. The cementation verification aid was fabricated using a polyvinylsiloxane bite registration material (Blu Mousse) to cement the crown onto the abutment extraorally to ensure proper alignment of the crown on the abutment. Cementation of the prosthesis occurred with no adjustments required to the interproximal or occlusal contacts during final delivery. This article provides a technique that aims to increase accuracy in the placement of the crown on the abutment when cementing screwmentable crowns.

Clinical evaluation and quantitative occlusal change analysis of posterior implant-supported all-ceramic crowns: A 3-year randomized controlled clinical trial

OBJECTIVES

To compare the survival and complication rates of posterior screw-retained monolithic lithium disilicate (LS2 )/veneered zirconia (ZrO2 ) single implant crowns (SICs), as well as analyze the occlusal changes observed during a 3-year follow-up period.

MATERIALS AND METHODS

Thirty-three patients were included and randomly divided into two groups. The test group consisted of 17 patients who received monolithic-LS2 -SIC, while the control group consisted of 16 patients who received veneered-ZrO2 -SIC. Implant/prosthesis survival rates, technical complications, peri-implant soft tissue conditions, and quantitative occlusal changes of SIC (obtained by the intra-oral scanner and analyzed in reverse software Geomagic Control 2015) were assessed at 1- and 3-year follow-ups. Bone loss and Functional Implant Prosthodontic Score (FIPS) were evaluated at a 3-year follow-up.

RESULTS

After a 3-year follow-up period, one patient dropped out of the follow-up. No implant loss was observed. One crown was fractured, resulting in prosthesis survival rates of 93.75% for the monolithic group and 100% for the veneered group. A technical complication rate of 25% (4/16) was observed in the veneered group (p = .333). No significant differences in the marginal bone loss were observed at the 3-year follow-up (0.00 (-0.22, 0.17) mm versus 0.00 (-0.12, 0.12) mm, p = .956). The total FIPS scores for the test group were 9.0 (9.0, 9.0), while the control group received scores of 9.0 (8.0, 10.0) (p = .953). The changes in mean occlusal clearance were 0.022 ± 0.083 mm for the test and 0.034 ± 0.077 mm for the control group (at 3 years, p = .497). The changes in occlusal contact area were 1.075 ± 2.575 mm2 for the test and 1.676 ± 2.551 mm2 for the control group (at 3 years, p = .873).

CONCLUSION

After a 3-year follow-up, screw-retained monolithic LS2 and veneered ZrO2 SIC demonstrated similar survival rates. The occlusal performance of implant prostheses needs to be closely examined during follow-up, and appropriate occlusal adjustments need to be considered.

Screw-Retained Surgical Guide for Implant Placement in Terminal Dentition Patients With Existing Implants

For patients with existing implants in need of additional implant placement, the use of the existing implants for guide fixation seems to be a logical alternative. Current options for the fabrication of surgical guides involve creating surgical guides that are mucosa-borne and/or retained by fixation pins. Since these existing techniques involve inherent inaccuracies, the fabrication of surgical guides that are screw-retained at the implant- or abutment-level would eliminate the introduction of those same fundamental inaccuracies. The purpose of the present technical report is to illustrate a step-by-step digitally planned guided implant placement protocol for terminal dentition patients with salvageable existing implants requiring full-arch implant rehabilitation. The advantages of this protocol include enhancing the accuracy of guided implant placement with screw-retention vs the traditional mucosa- or fixation pin support. Thus, this simplifies the transition from failing teeth to implants by ensuring that fixed provisionalization serves both functional and esthetic requirements. This protocol can also predictably reduce chairside time and adjustments at the surgical implant placement appointment. This article is protected by copyright. All rights reserved.

Five-year randomized controlled clinical study comparing cemented and screw-retained zirconia-based implant-supported single crowns

Objectives

To compare screw‐retained and cemented all‐ceramic implant‐supported single crowns regarding biological and technical outcomes over a 5‐year observation period.

Materials and methods

In 44 patients, 44 two‐piece dental implants were placed in single‐tooth gaps in the esthetic zone. Patients randomly received a screw‐retained (SR) or cemented (CR) all‐ceramic single crown and were then re‐examined annually up to 5 years. Outcome measures included: clinical, biological, technical, and radiographic parameters. Data were statistically analyzed with Wilcoxon–Mann–Whitney, Wilcoxon, and Fisher's exact tests.

Results

During the observation period, three patients (6.8%) were loss to follow‐up. Eight restorations (18.2%, CI (8.2%, 32.7%)) were lost due to technical (6 patients, 13.6% (CI (5.2%, 27.4%)), 2 CR and 4 SR group, intergroup p = .673; implants still present) or biological complications (2 patients, 4.5% (CI (0.6%, 16.5%)), only CR group, intergroup p = .201, both implants lost). This resulted in a survival rate of 81.2% (CI (65.9%, 90.1%)) on the restorative level (18 SR; 15 CR, 3 lost to follow‐up). At the 5‐year follow‐up, the median marginal bone levels were located slightly apical relative to the implant shoulder with 0.4 mm (0.5; 0.3) (SR) and 0.4 mm (0.8; 0.3) (CR) (intergroup p = .582). Cemented restorations demonstrated a significantly higher biological complication rate (36.8%, SR: 0.0%; intergroup p = .0022), as well as a significantly higher overall complication rate (68.4%, SR: 22.7%, intergroup p = .0049). All other outcomes did not differ significantly between the two groups (p > .05).

Conclusions

All‐ceramic single‐tooth restorations on two‐piece dental implants resulted in a relatively low survival rate. Cemented restorations were associated with a higher biological and overall complication rate than screw‐retained restorations.

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

Objectives

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

Materials and methods

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

Results

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

Conclusions

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

Evaluation and comparison of vertical marginal fit of three different types of multiunit screw-retained framework fabricated for an implant-supported prosthesis - An in vitro study

Aim

The present study aimed to evaluate on a comparative basis the vertical marginal fit between conventionally casted, direct metal laser sintered (DMLS), and milled computer-aided design/computer-aided manufacturing (CAD-CAM) one-piece metal framework supported by five implants using one-screw test and screw resistance test.

Settings and Design

This is an in vitro study.

Materials and Methods

Five implants were placed parallel to one other in a Styrofoam master model. A total of 30 implant-supported screw-retained superstructures were manufactured using three techniques, i.e., conventionally casted, milled, and sintered. To evaluate the vertical marginal discrepancy, screw resistance test, and one-screw test were used, and measurements were made using a stereomicroscope.

Statistical Analysis Used

The data was analysed using two statistical tests, i.e., ANOVA and the post hoc Bonferroni test.

Results

On evaluating the frameworks using one-screw test, the mean vertical misfit value at the terminal implant for the control group was 292.58 ± 15.46μm, for conventionally casted framework 398.41 ± 21.13 μm, for DMLS 343.44 ± 24.73 μm, and for CAD-CAM was 304.03 ± 14.23 μm, whereas the average misfit values at four implants on applying screw resistance test were 1268.65 ± 84.24 (control), 1774.88 ± 67.70 (casted), 1508.02 ± 62.19 (DMLS), and 1367.29 ± 81.87 (CAD-CAM). The average misfit values on two implants using screw resistance test were 635.02 ± 57.33 for the control group; for conventionally casted, it was 879.75 ± 35.93; for (DMLS) framework, it was 761.51 ± 32.85; and for milled CAD-CAM framework, it was 687.07 ± 42.17 μm.

Conclusion

The mean vertical marginal discrepancy, when compared with control, was least in milled CAD-CAM frameworks, followed by sintered DMLS and conventionally casted frameworks. Hence, according to the present study, CAD/CAM technique is recommended to achieve maximum marginal fit in full mouth screw-retained implant-supported FDPs.

The Application of Angulated Screw-Channels in Metal-Free, Implant-Supported Restorations: A Retrospective Survival Analysis

Angulated screw channels (ASC) allow the clinician to reposition the access hole of screw-retained restorations, improving the design of the rehabilitation and the esthetic outcome. Few clinical studies are available on the efficacy of these restorations, especially at longer follow-ups and with a large number of subjects. The objective of this study was therefore to retrospectively evaluate patients rehabilitated with screw-retained restorations using ASC. The time of delivery and their adherence to the maintenance program was obtained, as well as the characteristics of the restoration and of the patient's occlusion; a Kaplan-Meier survival curve was then built to investigate the success rate of these restorations and the effects of several variables were evaluated with a Cox model. A total of 105 subjects and 162 implants were enrolled in this study; after 42 months a success rate (92%) similar to what is reported for conventional screw-retained restorations was encountered. Monolithic zirconia restorations (n = 52) had a higher success rate (95%) when compared to partially veneered restorations (n = 53), which suffered a higher number of complications (90%). The other variables had no statistically significant effect. Implant supported prostheses adopting ASC provide a favorable outcome both in the posterior and anterior regions and can therefore be adopted to treat cases where the implant angulation is unfavorable for a conventional screw-retained prosthesis.

Peri-implant and esthetic outcomes of cemented and screw-retained crowns using zirconia abutments in single implant-supported restorations-A systematic review and meta-analysis

OBJECTIVES

To evaluate the peri-implant tissue changes and esthetic outcomes of cemented and screw-retained crowns of single-tooth implants in the esthetic zone using zirconia abutments.

MATERIAL AND METHODS

An electronic search was performed on nine databases. The risk-of-bias was assessed by the revised Cochrane risk-of-bias tool for randomized (RoB 2) and non-randomized (ROBINS-I) clinical trials. Marginal bone level change, soft tissue thickness, bleeding on probing, probing depth, survival rates of implants and crowns, complications, plaque and papilla indexes, and pink esthetic score data were extracted and analyzed. The certainty of evidence was accessed through the GRADE approach.

RESULTS

Nine records were included and 7 were used in the meta-analyses. Screw-retained crowns presented greater marginal bone level change (MD -0.04 [-0.08, -0.00] p = 0.04, I²  = 0%) compared to cemented crowns up to 1-year. At 3 and 4 years no significant differences (p > 0.05) were observed. Soft tissue thickness did not differ between groups (p > 0.05). The bleeding on probing was higher in cemented group than in screw-retained crowns at 1-year (MD 0.17 [0.08, 0.27] p = 0.0005, I²  = 0%), at medium-term periods (3 and 4 years) no statistically significant differences (p > 0.05) were observed for this outcome. Probing depth, survival rates of implants and crowns, complications, and plaque index, as well as esthetic analysis using the papilla index and pink esthetic score did not differ statistically (p > 0.05) between both retention systems at short and medium-term periods.

CONCLUSION

The connection system considering zirconia abutments presented no influence on peri-implant parameters and esthetics evaluation for medium-term periods (3 and 4 years).

Short communication: Cemented implant reconstructions are associated with less marginal bone loss than screw-retained reconstructions at 3 and 5 years of loading

OBJECTIVES

To analyse whether there is a difference in marginal bone levels (MBL) and the respective changes between cemented and screw-retained reconstructions at 3 and 5 years of loading.

METHODS

Radiographic data from 14 prospective multicentre clinical trials following implant loading with fixed cemented (CEM) or screw-retained (SCREW) reconstructions with a 3- to 5-year follow-up were retrieved from a database. MBL and MBL changes were assessed at initiation of implant loading (BL), at 3 (FU-3) and 5 years (FU-5) thereafter. The presence of peri-implantitis was also determined.

RESULTS

Data from 1,672 implants at BL, 1,565 implants at FU-3 and 1,109 implants at FU-5 were available. The mean MBL amounted to 0.57 mm (SD 0.87) at BL, 0.55 mm (SD 0.86) at FU-3 and 0.65 mm (SD 1.18) at FU-5. At FU-3, the mean MBL was 0.44 mm (SD 0.65) in group CEM and 0.63 mm (SD 0.99) in group SCREW showing a significant difference between the groups (intergroup <0.05). At FU-5, the mean MBL was 0.42 mm (SD 0.77) in CEM and 0.80 mm (SD 1.37) in SCREW, again with significant differences between both groups (p < .05). MBL changes between BL and FU-3 amounted to 0.11 mm (SD 1.02) (bone loss) in SCREW and -0.17 mm (SD 1.03) (bone gain) in CEM. Similarly, mean MBL changes from BL to FU-5 amounted to 0.23 mm (SD 1.31) (bone loss) in SCREW and -0.26 mm (SD 1.27) (bone gain) in CEM. The prevalence of peri-implantitis amounted to 6.9% in CEM and 5.6% in group SCREW (intergroup p = .29063) at FU-3. At FU-5, peri-implantitis amounted to 4.6% in CEM and 6.2% in group SCREW (intergroup p = .28242).

CONCLUSION

Cemented implant reconstructions compared with screw-retained reconstructions revealed higher marginal bone levels and similar rates of peri-implantitis during 5 years. The difference in MBL and the respective changes between the two groups, however, appear to be clinically negligible.

Ten-year Survival Rate of Cement- and Screw-retained Restorations on Bone-level Dental Implants in Grafted and Non-grafted Sites: A Retrospective Study

PURPOSE

The aim of the present 10-year follow-up study was to assess the survival rate of cement- and screw-retained restorations on dental implants placed in grafted sites.

MATERIALS AND METHODS

Patients with cement- (group 1) and screw-retained (group 2) restorations on implants placed in grafted sites and patients with cement- (group 3) and screw-retained (group 4) restorations on implants placed in non-grafted sites were included. Demographic data was recorded using a questionnaire, and information regarding implant dimensions, surface characteristics, insertion torque, type of bone graft used, jaw location and duration of implants in function was retrieved from patients' records. These patients were evaluated for peri-implant crestal bone loss (CBL), probing depth (PD), modified plaque index (mPI), and modified bleeding on probing (mBOP). p < 0.05 was considered statistically significant.

RESULTS

Eighty-eight partially edentulous individuals (n = 22 in each group) were included. The mean ages of individuals in all groups were comparable in all groups. In each patient, 1 bone-level platform-switched dental implant with moderately rough surfaces was placed using an insertion torque of 30-35 Ncm. In all groups, the length and diameter of implants ranged between 11-14 mm and 4.1-5 mm, respectively. There was no statistically significant difference in mPI, mBoP, PD, and mesial and distal CBR around implants in any of the groups.

CONCLUSION

Bone-level implants restored with cement and screw-retained restorations can possess a stable clinicoradiographic status and remain functional in grafted and non-grafted sites, provided strict domestic oral hygiene measures are adopted and routine dental prophylaxis is carried out by oral healthcare providers.

Fracture strength of various titanium-based, CAD-CAM and PFM implant crowns

OBJECTIVE

CAD-CAM has dramatically advanced dental restorative procedures to include implant-supported crowns. The purpose of this study was to compare the fracture resistance following mechanical loading and thermocycling of various screw-retained and cement-retained ceramic and polymethylmethacrylate material combinations using the TiBase abutment compared to PFM implant-supported crowns.

OVERVIEW

Twelve implant restorations were fabricated for each of eight groups. Three groups were screw-retained and five groups were cement-retained implant restorations. The ceramic and polymethylmethacrylate restorations were fabricated on the TiBase abutment while the PFM restorations were fabricated on an UCLA abutment. Data were analyzed with a one way Analysis of Variance and Tukey's post-hoc test to evaluate the effect of abutment and crown type on fracture load (alpha = 0.05). A significant difference was found in the maximum fracture load between groups (P < 0.001).

CONCLUSIONS

The screw-retained implant restorations demonstrated higher fracture loads than their cement-retained counterparts. The TiBase abutment compared favorably to the UCLA abutment.

CLINICAL SIGNIFICANCE

The TiBase abutment is a titanium insert which combines the esthetics of a ceramic abutment with the mechanical properties of a titanium abutment and should be considered a viable clinical alternative to the conventional implant-supported PFM crown based on theses in vitro results and in context of in vivo studies. The lithium disilicate hybrid abutment/crown implant-supported restoration utilizing the TiBase abutment may be an ideal clinical choice due to simplicity, single appointment CAD-CAM, and esthetics.

Complications of screw- and cement-retained implant-supported full-arch restorations: a systematic review and meta-analysis

PURPOSE

To assess the technical and biological complications of screw- and cement-retained implant-supported full-arch dental prostheses.

MATERIALS AND METHODS

An electronic search was conducted on Medline/PubMed and Cochrane databases in February 2019; irrespective of any time restrictions using MeSH terms. All studies were first reviewed by abstract and subsequently by full-text reading. Further hand search was performed to identify other related references. Articles only related to cement-retained and/or screw-retained reconstructions in full-arch fixed dental prostheses (FDP) were included.

RESULTS

The initial literature search resulted in 3670 papers. 3478 articles remained after removing duplicate articles, and 3439 articles were further excluded by the reviewers after the abstract screening, which resulted in a selection of 39 studies. 12 studies were further excluded due to not fulfilling the inclusion criteria. Hand searching resulted in two additional papers being included, and finally, 29 articles were included in this review. Screw-retained full-arch fixed dental prostheses have fewer complications than cemented reconstructions. Biological complications such as marginal bone loss > 2 mm occurred more frequently in cemented reconstructions, and technical complications such as screw-loosening and screw fracture occurred more in screw-retained reconstructions.

CONCLUSION

Cemented reconstructions exhibited more biological complications (implant loss, bone loss > 2 mm) and screw-retained prostheses exhibited more technical problems. Clinical outcomes were influenced by both fixations in different ways. The screw-retained restorations were more easily retrievable than cemented ones, therefore, technical and eventually biological complications could be treated more easily. For this reason, and for their higher biological compatibility, these reconstructions are preferable.

Guided-welded approach planning using digital scanning technology for combined screw- and conometric-retained implant-supported maxillary prosthesis

AIM

The goal of this case series was to evaluate the clinical outcome at the 2-year follow-up of immediately loaded combined screw- and conometric-retained implant-supported full-arch restorations virtually planned using digital scanning technology.

MATERIALS AND METHODS

This series included 12 patients presenting hopeless teeth in the maxilla treated with computer-guided flapless implant placement. A total of 72 implants were inserted. All implants were immediately loaded with a complete-arch restoration supported by an intraorally welded framework. Digital scanning technology was used to virtually plan a combined screw and conometric retention of the frameworks. Clinical parameters were assessed at 1 week and at 1, 3, 6, 12, and 24 months follow-up.

RESULTS

The survival rate after 2 years was 98.6%, as one implant failed during the osseointegration period. No major prosthetic complications were observed such as issues with mobility, unscrewed abutments, disconnected conometric copings, and prosthetic fracture. Only one patient registered the chipping of a prosthesis.

CONCLUSION

Based on the results of the present study, the use of combined screw and conometric retention for fixed immediate restorations properly planned using digital scanning technology seems to be a viable treatment alternative to screw or conometric retention alone for immediately loaded rehabilitations.

Influence of Biologically Oriented Preparation Technique on Peri-Implant Tissues; Prospective Randomized Clinical Trial with Three-Year Follow-Up. Part II: Soft 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 of 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). After three years in function, clinical parameters (presence of keratinized mucosa, probing depths, bleeding on probing, and radiographic bone loss) were compared between the three experimental groups. The possible correlation between soft tissue clinical parameters and bone loss was also analyzed. Results: Statistical analysis found significant differences in clinical parameters between the different types of crown, with the cemented restoration without finishing line (BOPT) presenting fewer complications and better peri-implant health outcomes including: significantly different KMW data (mm), with significant differences between groups GBOPT and GCC (p < 0.001, Kruskal-Wallis test), with GBOPT obtaining larger quantities of keratinized mucosa (KM); statistically significant differences in probing depth (PD) values between groups GBOPT and GCC (p = 0.010, Kruskal-Wallis test); significant differences in bleeding on probing (BOP) between groups GBOPT and GCC (p = 0.018, Chi² test) in favor of GBOPT. Conclusions: Soft tissue behavior around implants is related to the type of prosthetic restoration used, with cemented prostheses with BOPT presenting better peri-implant soft tissue behavior.

Patient-centered rehabilitation of single, partial, and complete edentulism with cemented- or screw-retained fixed dental prosthesis: The First Osstem Advanced Dental Implant Research and Education Center Consensus Conference 2017

The aim of this consensus conference was to provide clinical guidelines, based on the available evidence and on the author's daily practice and experience, for general dentistry and dental practitioners to allow them to delivery long-term successful restorations. Three groups of expert clinicians and dental technicians were invited to evaluate all of the scientific literature from 1967 up to March 2017 to identify relevant studies on assigned topics and to prepare in advance narrative/systematic review, written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, to fulfill the consensus statement criteria. The three topics assigned to the three groups were abutment/framework materials and customization (metal vs. metal-free restorations), abutment/framework protocols and designs, and abutment/framework retentions (cemented- vs. screw-retained implant-supported prostheses). All the expert clinicians presented their results, and the lectures were followed by discussions. No significant differences in clinical parameters (marginal bone loss, bleeding on probing, and pocket probing depth) between screw- or cemented-retained were found for single and multiple implant-supported restorations. There is moderate evidence that nonoriginal abutments provide worse mechanical behavior than originals and high evidence that different implant neck designs do not offer any clinical or radiographic advantage. All the participants agreed that it is desirable to connect and remove abutments as few times as possible. There is medium evidence that an adequate platform switching tends to enhance tissue volume and stability in the medium- and long-term follow-up. No statistically significant differences exist between metal and zirconia as a framework material. The authors discussed and all agreed that retrievability and patient's expectation (function and esthetics) should guide the choice of the most adequate technique, component, and material.

Intrasubject comparison of digital vs. conventional workflow for screw-retained single-implant crowns: Prosthodontic and patient-centered outcomes

OBJECTIVES

The aim of this intrasubject clinical study was to measure and compare prosthodontic and patient-reported outcome measures (PROMs) in the fabrication of implant-supported, all-ceramic single crowns with a full digital workflow and a conventional workflow.

MATERIALS AND METHODS

Thirty-one patients were subjected to first a digital (test group) and then a conventional impression (control group) at the same visit. From the intraoral optical scanner (IOS), a screw-retained, monolithic crown was delivered according to a complete digital workflow (no cast), whereas a veneered crown on a zirconia (Zi) frame was provided as a control treatment. Both crowns were assessed during the clinical stages of try-in. Prosthodontic outcomes (contact points, occlusion, PROMs, and esthetic results using the white esthetic score [WES]) were assessed.

RESULTS

Occlusion and interproximal contacts showed comparable results for the two workflows (p = 0.37 and p = 0.36, respectively), whereas the global WES was significantly higher (p < 0.0001) in the control group. Patient satisfaction scores, using visual analog scales (VAS), were significantly better for IOS than for conventional impressions (p = 0.0098). On the contrary, patients' perception of the esthetic outcomes showed significantly higher value (p < 0.0001) in the control group.

CONCLUSIONS

Both workflows allowed the delivery of ceramic crowns within two appointments. The clinical fit was acceptable in both groups. A better esthetic outcome, in both patients' and clinicians' opinions, was found in the control group. PROMs showed higher satisfaction with the IOS.

Randomized Controlled Clinical Trial to Compare Posterior Implant-Supported Modified Monolithic Zirconia and Metal-Ceramic Single Crowns: One-Year Results

PURPOSE

The purpose of this randomized controlled clinical trial was to investigate the prosthetic outcomes of posterior implant-supported single crowns (SCs) with a modified monolithic zirconia or metal-ceramic design at 1 year of loading.

MATERIALS AND METHODS

Forty participants with 73 dental implants in need of at least 1 maxillary or mandibular posterior implant-supported SC were consecutively selected for this study. The included participants were randomly divided into modified monolithic zirconia (MMZ) and metal-ceramic (MC) groups. The implant-supported SCs were examined after 1 year for survival and technical complications. Descriptive statistics were used to illustrate the data, and the association associated risks of complications were estimated using the logistic regression model with Firth's approach for rare outcome (α = 0.05).

RESULTS

During the observation period, 2 participants in the MC group were lost to follow-up. A total of 38 participants with 70 posterior implant-supported SCs (36 and 34 SCs in the MMZ and MC groups respectively) completed the 1-year follow-up examination. One implant failed in the MMZ group. The 1-year survival rates for implants and crowns were both 97.2% in the MMZ group. The survival rates for implants and crowns were both 100% in the MC group. One screw loosening event was observed in one screw-retained SC in the MMZ group; however, 8 complication events occurred in 7 SCs in the MC group. Therefore, the complication-free rates were 97.1% and 79.4% in the MMZ and MC SCs respectively. The most common complication in the MC group was screw loosening (14.7%), followed by loss of retention (5.9%), and ceramic fracture (2.9%). Significantly more technical complications were observed in the MC SCs than MMZ SCs (p = 0.0432).

CONCLUSION

The modified monolithic zirconia design applied to the posterior implant-supported SCs had a significantly lower technical complication rate than did the metal-ceramic one.

Full-Arch, Implant-Supported Monolithic Zirconia Rehabilitations: Pilot Clinical Evaluation of Wear Against Natural or Composite Teeth

PURPOSE

To clinically evaluate the amount of contact wear generated between full-arch monolithic zirconia implant-supported restorations and natural or composite antagonists, over a 1-year period.

MATERIALS AND METHODS

Forty-seven teeth from clinically functional, full-arch monolithic zirconia screw-retained implant prostheses (FDPs) and their antagonists were investigated. The first group ("Zirconia-E") was opposed to natural teeth ("Enamel"), whereas the other one ("Zirconia-CR") was opposed to nano-hybrid composite teeth ("Composite Resin"). Replicas of the restorations and their antagonists were obtained immediately after delivery (T₀ ) and after 1 year of clinical service (T₁ ). Each tooth surface was individually evaluated three-dimensionally by software to quantify the vertical distance between the two scans (Hausdorff distance), which was considered as contact wear. Data obtained for each arch were subjected to one-way ANOVA test and a post hoc analysis (Tukey's test) at a 5% level of significance. Furthermore, the influence of the location of the teeth (anterior or posterior) was analyzed. Minimum post hoc statistical power between statistically different groups was 99.6%.

RESULTS

Mean values were 63 ± 23 μm for Zirconia-E, 76 ± 29 μm for enamel, 70 ± 38 μm for composite resin; Zirconia-CR had a mean value of 19 ± 4 μm and significantly differed from the other groups. Contact wear between anterior and posterior teeth differed significantly only in the composite resin arch, with a mean of 39 ± 22 μm for anterior teeth versus 101 ± 19 μm for posterior ones.

CONCLUSIONS

Within the limitations of this preliminary evaluation, monolithic zirconia full-arch rehabilitations induced a clinically acceptable wear on natural and composite antagonists over a 1-year period; they might be considered a viable solution for implant-supported rehabilitations.

In vitro evaluation of a modified 4-META/MMA-TBB resin for filling access holes of screw-retained implant prostheses

This study evaluates a modified 4-META/MMA-TBB resin (M4M) as a candidate material for filling screw-retained implant access hole. Its characteristics were compared with a conventional composite resin (CR) with or without a bonding agent (BA) or a ceramic primer (CP). Ceramic blocks were divided into five groups, including (A) CR, (B) CR with BA, (C) CR with CP and BA, (D) M4M, and (E) M4M with CP. Shear bond strengths were measured after 5000 times of thermocycling. Groups A, B, and D were excluded from further tests as they showed no adhesion. A cylindrical cavity (2.5 mm diameter, 3 mm depth) simulating access hole was prepared in a ceramic block and glazed to evaluate micro-leakage and wear test of groups C and E. The results were statistically analyzed with Mann-Whitney test (p  <  0.05). Shear bond strength of groups C (7.6 ± 2.2 MPa) and E (8.6 ± 1.0 MPa) was not significantly different. In micro-leakage analysis, average wear depth and wear volume, group E (7.5 ± 3.3%, 59.3 ± 12.9 μm, 0.16 ± 0.04 mm(3) ) showed significantly lower values than those of group C (45.6 ± 24.4%, 76.0 ± 16.4 μm, 0.28 ± 0.03 mm(3) ). It is suggested that the combination of CP and M4M can be one of feasible systems to fill the ceramic access holes of the implant upper structure.