Device trueness in passivity and misfit of CAD-CAM frameworks: Conventional versus printed casts.

STATEMENT OF PROBLEM: Obtaining a passive and well-adapted framework is challenging when intraoral scanning edentulous arches with multiple implants. The trueness of the printed casts is unclear. PURPOSE: The purpose of this clinical study was to evaluate the trueness of frameworks made from conventional and printed casts regarding clinical passivity and misfit. MATERIAL AND METHODS: Ten participants with complete mandibular fixed implant-supported interim prostheses retained by 4 implants were included. Each participant had a conventional impression and a digital scan made. The digital scan was made using an innovative device. Both conventional and digital casts were made, and the virtual images were used for milling the digital framework in cobalt chromium alloy. All frameworks were evaluated for passivity and marginal vertical misfit with the single screw test, with 4 attempts consisting of the tightened screw position, a test with all screws tightened, and an interspersed tightening test. The Kruskal-Wallis test was used to evaluate the trueness of the tested device for framework construction through the single screw test on vertical marginal misfit in the conventional and printed groups (α=.008). The Friedman test was used to assess the effect of test type (α=.05), and the Wilcoxon test was used to identify group-to-group differences (α=.017). RESULTS: The absence of space between the framework and the abutments and interferences during its placement, as well as good stability, were observed clinically. In laboratory analysis, greater framework misfits were observed in the printed group compared with the conventional group when the single screw test was applied. Comparing the 3 tests used, the greatest misfits were observed when the framework was screwed onto the printed cast. CONCLUSIONS: The innovative device tested for the intraoral scanning of multiple implants had clinically acceptable accuracy for the construction of passive and adapted frameworks. The conventional cast was more accurate than the printed cast, with lower misfit values, in all tests.

Partially digital workflow for making complete-arch implant-supported fixed prostheses: A dental technique.

This article describes a technique for making complete-arch implant-supported fixed prostheses by using intraoral scanning and computer-aided design and computer-aided manufacturing (CAD-CAM) technology for the fabrication of a metal substructure and conventional processing for the prosthesis base. For this, a device was designed to accurately capture the position of multiple implants and the associated digitalized surgical guide, and the metal substructure was planned and milled directly in cobalt-chromium. The color of the gingiva and artificial teeth was selected by using the intraoral scanner software program, and the prosthesis base was processed conventionally. The straightforward methods used to fabricate the prostheses eliminated possible errors associated with conventional substructure casting and occlusal registration.

Survival and prosthetic complications of monolithic ceramic implant-supported single crowns and fixed partial dentures: A systematic review with meta-analysis.

STATEMENT OF PROBLEM: Monolithic ceramic implant-supported restorations have been used to rehabilitate partially edentulous patients. However, knowledge of the survival and prosthetic complications of single crowns (SCs) and fixed partial dentures (FPDs) is limited. PURPOSE: The purpose of this systematic review with meta-analysis was to evaluate the clinical performance of monolithic ceramic implant-supported SCs and FPDs in terms of survival and prosthetic complication rates. MATERIAL AND METHODS: The systematic review was registered on the prospective register of systematic reviews (PROSPERO) (CRD42017078568). Five electronic databases were independently searched by 2 authors for articles published until May 2022. In addition, a hand search was performed in the nonpeer-reviewed literature, specific journals, and reference lists of included articles. A single-arm meta-analysis was performed by using the R program. The risk of bias and quality were assessed using the Cochrane risk of bias tools and the Newcastle-Ottawa scale. RESULTS: Twenty-eight studies were included in the quantitative synthesis. A total of 1298 monolithic ceramic implant-supported restorations (1116 SCs and 182 FPDs) were evaluated in 1193 participants, with a median observation time of 24 months (range: 12 to 72 months). Meta-analysis indicated the proportion of failures and prosthetic complication rates of 2% (95% confidence interval [CI]: 1% to 4%) for SCs. No difference was observed for monolithic zirconia and lithium disilicate SCs. In the FPDs, only monolithic zirconia was considered, with 1 failure reported totaling the proportion of failures of 0% (0% to 1%) and complication rates of 4% (0% to 12%). The most complications reported for both types of restorations were screw loosening, debonding, and minor chipping and were considered repairable. The included studies showed a low risk of bias and good quality. CONCLUSIONS: The use of monolithic ceramic implant-supported SCs, independent of ceramic material, and monolithic zirconia implant-supported FPDs should be considered an effective and safe treatment option because of favorable short-term survival and low prosthetic complications. However, additional well-conducted studies with a longer-term follow-up and direct comparison between veneered restorations are recommended to reassess clinical performance.

The influence of nocturnal use of complete dentures on cardiorespiratory parameters of patients with obstructive sleep apnea: a systematic review and meta-analysis.

OBJECTIVE: To assess whether wearing complete dentures during sleep influences the cardiorespiratory parameters of patients with obstructive sleep apnea (OSA). MATERIALS AND METHODS: A systematic review was performed based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to determine whether wearing complete dentures during sleep influences the cardiorespiratory parameters of patients with OSA. An electronic search was performed in four databases, PubMed/MEDLINE, Cochrane Library, Web of Science, and SCOPUS, and in the gray literature (TRIALS) until November 2021. This review included clinical trials, randomized clinical trials, and studies in which patients using conventional complete dentures were diagnosed with OSA using polysomnography and the cardiorespiratory parameters were measured using oximetry or polysomnography during sleep. RESULTS: In total, 788 references were found in the database, and 12 articles were selected for full reading. Six articles were selected for qualitative and quantitative analyses after applying the inclusion and exclusion criteria and reading the full article. The meta-analysis showed that mean oxygen saturation (SpO2) increased with the use of complete dentures (p = 0.001), but the other parameters showed no significant differences between those wearing and not wearing dentures during sleep. CONCLUSIONS: The mean SpO2 reduced in patients wearing complete dentures, but the other cardiorespiratory parameters evaluated were not affected. CLINICAL RELEVANCE: This study indicates a possible influence of the use of complete dentures on the mean SpO2 during sleep. The use of complete denture could aid other treatments in improving respiratory and sleep quality.

Biomechanical Evaluation of Different Implant-Abutment Connections, Retention Systems, and Restorative Materials in the Implant-Supported Single Crowns Using 3D Finite Element Analysis.

This is an in silico study aimed to evaluate the biomechanical influence of different implant-abutment interfaces (external hexagon and Morse taper implants), retention systems (cement and screw retained), and restorative crowns (metal-ceramic and monolithic) using 3-dimensional finite element analysis (3D-FEA). Eight 3D models were simulated for the maxillary first molar area using InVesalius, Rhinoceros, and SolidWorks and processed using Femap and NEi Nastran software. Axial and oblique forces of 200 and 100 N, respectively, were applied on the occlusal surface of the prostheses. Microstrain and von Mises stress maps were used to evaluate the deformation (cortical bone tissue) and stress (implants/fixation screws/crowns), respectively, for each model. For both loadings, Morse taper implants had lower microstrain values than the external hexagon implants. The retention system did not affect microstrain on the cortical bone tissue under both loadings. However, the cemented prosthesis displayed higher stress with the fixation screw than the external hexagon implants. No difference was observed between the metal-ceramic and zirconia monolithic crowns in terms of microstrain and stress distribution on the cortical bone, implants, or components. Morse taper implants can be considered as a good alternative for dental implant rehabilitation because they demonstrated better biomechanical behavior for the bone and fixation screw as compared to external hexagon implants. Cement-retained prosthesis increased the stress on the fixation screw of the external hexagon implants, thereby increasing the risk of screw loosening/fracture in the posterior maxillary area. The use of metal-ceramic or monolithic crowns did not affect the biomechanical behavior of the evaluated structures.

Clinical comparison between crestal and subcrestal dental implants: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: How the performance of dental implants is related to their occlusogingival placement, crestal or subcrestal, is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate marginal bone loss, implant survival rate, and peri-implant soft tissue parameters between implants placed at the crestal and subcrestal bone level. MATERIAL AND METHODS: Two independent reviewers searched the PubMed/MEDLINE, Embase, and Cochrane Library databases for randomized clinical trials published up to September 2020. The meta-analysis was based on the Mantel-Haenszel and the inverse variance methods (α=.05). RESULTS: The search identified 928 references, and 10 studies met the eligibility criteria. A total of 393 participants received 709 implants, 351 at crestal bone levels and 358 at subcrestal bone levels. Meta-analysis indicated that crestal bone level implants showed similar marginal bone loss to that seen with subcrestal bone level implants (mm) (P=.79), independent of the subcrestal level (P=.05) and healing protocol (P=.24). The bone level implant placement did not affect the implant survival rate (P=.76), keratinized tissue (mm) (P=.91), probing depth (mm) (P=.70), or plaque index (%) (P=.92). CONCLUSIONS: The evidence suggests that both approaches of implant placement are clinically acceptable in terms of peri-implant tissue parameters and implant-supported restoration survival.

Does non-surgical periodontal treatment influence on rheumatoid arthritis? A systematic review and meta-analysis.

OBJECTIVE: The objective of this systematic review was to evaluate the efficacy of non-surgical periodontal therapy on rheumatoid arthritis activity. MATERIAL AND METHODS: Articles published until April 2019 were electronically searched and screened using PubMed / MEDLINE, Scopus, and Cochrane databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA). This study was recorded in the international PROSPERO database (CRD42019132205). The PICO question (population, intervention, comparison, results) was: in adult patients with rheumatoid arthritis and periodontitis (P), does non-surgical periodontal treatment (I), as compared to no treatment (C), provides better outcomes in rheumatoid arthritis activity (O). RESULTS: After searching the databases, seven articles were selected for qualitative and five for quantitative analysis. The total number of participants included was 292, with an average age of 50.5 years. All patients had rheumatoid arthritis and periodontal disease. Non-surgical periodontal treatment significantly reduced Disease Activity Score 28 (P = 0.004; I2 = 92%) and erythrocyte sedimentation rate (P = 0.01; I2 = 78%), but with no significant effect on C-reactive protein (P = 0.34; I2 = 92%). CONCLUSIONS: It can be concluded that non-surgical periodontal treatment can benefit patients with rheumatoid arthritis.

Effect of bone quality and bone loss level around internal and external connection implants: A finite element analysis study.

STATEMENT OF PROBLEM: A consensus regarding the biomechanical effects of vertical bone loss in normal and osteoporotic bone tissue according to different implant-abutment interfaces is lacking. PURPOSE: The purpose of this finite element analysis study was to evaluate the effect of vertical bone loss (without bone loss; with 1.5-mm bone loss; with 3-mm bone loss; and with 4.5-mm bone loss) in normal and osteoporotic bone that received a Ø4×10-mm implant with different implant-abutment connections (external connection [external hexagon] and internal connection [Morse taper]) by using 3D finite element analysis. MATERIAL AND METHODS: Sixteen 3D models were simulated. Axial and oblique forces of 200 N and 100 N, respectively, were applied on the occlusal surfaces of the prostheses. Maximum principal stress and microstrain were determined from the bone tissue of each model. von Mises stress analysis was used to evaluate the stress distribution in implants and prosthetic components (fixation screws, abutment, and crown). RESULTS: The results showed higher stress concentrations in models with bone loss as increased vertical bone loss contributed to higher stress and microstrain in the bone tissue, regardless of the quality of bone and implant-abutment connection. Osteoporotic bone contributed to increase in microstrain in the trabecular bone. The internal connection showed lower stress than the external connection implants only in models without marginal bone loss. Furthermore, higher stress concentrations were observed in the implants and fixation screws in models with increased bone loss and external connection implants, mainly under oblique loading. Osteoporotic bone did not affect stress distribution in the implants and prosthetic components. CONCLUSIONS: Progressive bone loss contributed to higher stress in the bone tissue, implants, and prosthetic components. The osteoporotic bone affects only the microstrain in the trabecular bone, but not the stress in the implants and prosthetic components. The internal connection implants showed lower stress in the cortical bone only in models without bone loss, while external connection implants exhibited higher stress in the implants and screws under oblique loading.

Pterygomaxillary Disjunction and its Influence on the Result of Surgically Assisted Maxillary Expansion: A Systematic Review and Meta-analysis.

AIM: The aim of this study was to evaluate the available evidence to identify the influence of pterygomaxillary disjunction on the result of surgically assisted maxillary expansion. BACKGROUND: LeFort I type osteotomy with disjunction of the pterygomaxillary suture is a procedure widely used in maxillofacial surgery. However, the need for its performance during surgically assisted maxillary expansions has been discussed in literature, since serious complications can be caused during this stage. REVIEW RESULTS: Systematic review of articles was performed using three databases (PubMed, Web of Science, and Cochrane) published until May 2019. After applying the selection criteria, five articles were included in the systematic review, with a total of 141 patients. Meta-analysis showed the absence of significant difference between intervention and control groups in the preoperative period (standardized mean difference = -0.28; confidence interval, CI 95% = -0.81, 0.26; p = 0.31) and postoperative period (standardized mean difference = -0.12; 95% CI = -0.65, 0.42; p = 0.66). In general, the heterogeneity of statistical estimates was low (I2 = 0%). CONCLUSION: No statistically significant difference was observed between control group (without pterygomaxillary disjunction) and intervention group (with pterygomaxillary disjunction). CLINICAL SIGNIFICANCE: Based on the data analyzed in this systematic review, it could be concluded that pterygomaxillary disjunction is not a mandatory step to achieve satisfactory maxillary expansion. Thus, not performing pterygomaxillary disjunction can prevent complications and reduce surgical time.

Quality Assessment of Systematic Reviews on Platform-Switching vs Platform-Matched Implants: An Overview.

The objective of this study was to perform a quality analysis of systematic reviews with meta-analyses that focused on the comparison of platform-switching (implant-abutment mismatching) and platform-matched (PM) implants. The assessment of multiple systematic reviews (AMSTAR) and Glenny (Checklist) Scales were used to qualify the studies. PubMed, Scientific Electronic Library Online (SciELO), Web of Science (formerly ISI Web of Knowledge), and Cochrane databases were searched, by topic, for systematic reviews on dental implants with switching platforms. A total of 8 systematic reviews, including 7 studies with meta-analyses, were selected. The AMSTAR scale indicated a high (n = 6) to moderate (n = 2) score for the included studies. The quantitative analysis indicated that platform-switching implants preserved more bone tissue when compared with platform-matched implants (6 meta-analyses; P < .001, smaller mean difference: -0.29 mm, 95% CI: -0.38, -0.19 and greater mean difference: -0.49 mm, 95% CI: -0.73, -0.26). Quantitative analysis based on 7 systematic reviews with meta-analysis indicated positive peri-implant bone preservation for implants restored with an implant-abutment mismatching (PSW). Further, there is evidence to improve the design of current systematic reviews. Future systematic reviews in this thematic area should consider searches in gray literature and different databases and include only randomized controlled clinical studies.

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.

Evaluation of Marginal Misfit of Implant-Supported Fixed Prostheses Made Using Different Techniques.

PURPOSE: To evaluate the vertical marginal (VM) and horizontal marginal (HM) misfit of frameworks made using different techniques. MATERIALS AND METHODS: A total of 30 frameworks were divided into three groups of 10 samples each based on manufacturing technique: nichrome cast (G1), milled in zirconia (G2), and milled in wax and fused to metal (G3). Marginal misfit was measured using a three-dimensional optical microscope. RESULTS: The highest VM misfit was in G3 (83.5 µm), followed by G1 (55 µm) and G2 (42 µm). The highest HM misfit was in G2 (118 µm), followed by G3 (102 µm) and G1 (-85 µm). CONCLUSION: Frameworks milled in zirconia resulted in the lowest VM misfit, while frameworks filled in wax and fused to metal resulted in higher VM. The HM misfit was favorable in the lost-wax technique.

Influence of Diabetes on the Survival Rate and Marginal Bone Loss of Dental Implants: An Overview of Systematic Reviews.

We aimed to conduct an analysis of the systematic reviews (SRs) in literature about the implant survival rate (ISR) and marginal bone loss (MBL) in diabetic and nondiabetic patients. This work was registered in The International Prospective Register of Systematic Reviews (CRD42018095314) and was developed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Cochrane Library Handbook. A search was performed on PubMed, Cochrane, Scopus, Embase, and LILACS. The PICO (problem/patient/population, intervention/indicator, comparison, outcome) question was "Do the survival rates of dental implants and marginal bone loss differ between diabetic and nondiabetic patients?" A total of 130 articles were retrieved. After eliminating repetitions, 118 were reviewed. Finally, 6 SRs were included. All the reviews indicated that there is no effect of diabetes on the ISR; however, a negative effect of the disease can be observed in MBL. Analysis of the quality of the studies was performed using the assessment of SRs in dentistry (Glenny Scale) and Assessing the Methodological Quality of Systematic Reviews (AMSTAR 2). Glenny Scale showed a moderate to high quality of the included studies. In contrast, AMSTAR 2 pointed out a critically low level for 4 studies, with no study fulfilling the criteria for high quality. It may be concluded that there is no effect of diabetes on the ISR; however, a negative effect of the disease can be observed on MBL.

CAD/CAM vs Conventional Technique for Fabrication of Implant-Supported Frameworks: A Systematic Review and Meta-analysis of In Vitro Studies.

PURPOSE: To compare the marginal vertical misfit between implant-supported frameworks fabricated using CAD/CAM systems and the conventional technique (lost-wax casting). MATERIALS AND METHODS: This review was performed according to PRISMA criteria and registered on PROSPERO (CRD42017055685). An electronic search was performed independently by two examiners in the MEDLINE (Pubmed), Embase, Web of Science, and Cochrane Library databases to find studies published up to April 2018. RESULTS: The database search yielded 507 references. After removing duplicate references, 384 studies remained. Eleven in vitro studies were selected according to the eligibility criteria (inter-reader κ = 0.88). Nine different CAD/CAM systems were used to fabricate 172 frameworks of different materials, including zirconia, monolithic lithium disilicate, and metallic alloys. Subgroup analyses were performed for different types and retention systems of the frameworks. In the general analysis, marginal misfit observed with the CAD/CAM systems was lower than with the conventional method (P = .003), as was observed in the subgroup analysis for single-unit frameworks (P < .00001). For fixed (P = .89), cemented (P = .60), and screwed (P = .18) frameworks, no significant difference was observed between the evaluated techniques. CONCLUSION: The CAD/CAM systems showed improved marginal fit over the conventional lost-wax casting technique for fabricating single-unit frameworks; however, in the subgroup analyses, no difference was observed for the fixed implant-supported type or for the retention systems evaluated.

Optimal number of implants for complete-arch implant-supported prostheses with a follow-up of at least 5 years: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Consensus is lacking regarding the optimal number of implants for supporting complete-arch prostheses with good survival rates and lower prosthetic complications and marginal bone loss. PURPOSE: The purpose of this systematic review was to evaluate the influence of the number of implants used for complete-arch prostheses with at least 5 years of follow-up. MATERIAL AND METHODS: A search was performed in the PubMed/MEDLINE, Scopus, and Cochrane Library databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria and was registered in The International Prospective Register of Systematic Reviews (CRD42016048468). The following was the population, intervention, comparison, outcome (PICO) question: Does the number of implants influence the longevity of complete-arch prostheses? RESULTS: Nineteen studies including 1006 patients with a mean age of 61.44 years were selected for evaluation. The number of implants per jaw ranged between 2 and 9 in the maxilla, mandible, or both jaws. For implant survival rate in complete-arch prostheses with fewer than 5 implants per jaw, the pooled weighted event rate was 1.4% (I2=25.26%; P=.211) and 4.2% (I2=81.35%; P<.001) for complete arches with more than 4 implants per jaw. For the prosthesis survival rate, the pooled weighted event rate for a complete-arch with fewer than 5 implants per jaw was 1.5% (I2=0%; P=.677) and 9% (I2=17.33%; P=.304) for complete arches with more than 4 implants per jaw. For prosthesis complications for complete arches with fewer than 5 implants per jaw, the pooled weighted event rate was 19.9% (I2=93.5%; P<.001) and 24.5% (I2=88.89; P<.001) for complete arches with more than 4 implants per jaw. The mean marginal bone loss for complete arches with fewer than 5 implants per jaw was 1.22 ±0.49 mm (I2=99.46; P<.001) and 1.46 ±0.46 mm (I2=99.6; P <.001) for more than 4 implants per jaw. CONCLUSIONS: The current systematic review indicated no relationship of the number of implants used to support a complete-arch prosthesis with implant survival rate, prosthesis survival rate, prosthesis complications, or marginal bone loss in studies with follow-up periods of between 5 and 15 years.

Does the Presence of a Cantilever Influence the Survival and Success of Partial Implant-Supported Dental Prostheses? Systematic Review and Meta-Analysis.

PURPOSE: To investigate if the presence of a cantilever influences the survival and success of partial fixed implant-supported prostheses, through a systematic review and meta-analysis, with additional analysis of the survival and marginal bone loss rates and prosthesis complications. MATERIALS AND METHODS: The register protocol of the review in the PROSPERO database is CRD42016052008. The MEDLINE and Scopus databases were used for an electronic search of relevant studies up to November 2016, by means of two independent reviewers. The keywords included the combinations "fixed partial denture" with "dental implants", and with "extension" or "cantilever"; and "implant-supported dental prosthesis" with "extension" or "cantilever". The inclusion criteria were randomized clinical trials and prospective and retrospective clinical studies in English that addressed the comparison of success and survival of the use of implant-supported fixed prostheses, with and without cantilevers. Data from the selected studies were used to perform the statistical analysis. RESULTS: Among the 408 articles identified, 4 articles met the eligibility criteria. The presence of a cantilever did not compromise marginal bone loss or the survival of the prostheses. However, minor complications were encountered for the group of partial fixed prostheses without cantilevers, with a statistical difference (P = .008). CONCLUSION: Cantilevers can be used in fixed prostheses and do not interfere negatively in the survival or success of the prosthesis or the marginal bone loss. However, there are minor complications when prostheses without cantilevers, or short cantilevers, are used.