3D-printed and conventional provisional single crown fabrication on anterior implants: A randomized clinical trial.

OBJECTIVES: The present study aims to compare provisional single crowns on anterior implants made using conventional PMMA and 3D-printed workflows. The study assessed the occurrence of failures, color variation, signs of early deterioration, operating time, and patients' satisfaction with the treatment through a randomized controlled trial. METHODS: This study was conducted as a randomized controlled trial, following the SPIRIT and CONSORT guidelines. Patients were included in the study after meeting the eligibility criteria and were randomly assigned to one of two groups (conventional and 3D-printed). FDI criteria, visible plaque index (VPI), bleeding on probing (BOP), and color variation were considered as the primary outcomes. Operating time and patient satisfaction were also assessed as secondary outcomes. Fisher's exact test was performed to analyze the association between the primary and secondary outcomes and the study groups. Mann-Whitney test was used to compare the mean VAS satisfaction scores between the conventional PMMA and 3D-printed groups (STATA 14™, with an α = 0.05). RESULTS: A total of 42 provisional single crowns (n = 21) were made for 33 patients. Only the fracture parameter (FDI) showed a statistically significant difference, with 3D-printed provisionals exhibiting higher rates of catastrophic failures compared to conventional ones (p = 0.05). Although the operating time for the 3D-printed group was shorter (p < 0.001), no statistical difference observed in patients' satisfaction regarding esthetics, phonetics, chewing, or comfort. SIGNIFICANCE: 3D-printed and conventional PMMA provisional single crowns showed comparable clinical performance, except for the observed fracture types. Although 3D-printed provisional restorations showed a shorter operating time, overall patients' satisfaction was not affected.

Endodontic therapy in patients with inherited bleeding disorders: a scoping review.

This systematic scoping review aimed to map available evidence regarding endodontic therapy in patients with inherited bleeding disorders (IBDs). Studies in medicine or dentistry were selected if they reported on endodontic therapy in individuals with IBDs such as hemophilia A, hemophilia B, or von Willebrand disease. Two independent researchers performed searches and screening in PubMed/MEDLINE, Embase, Scopus, Web of Science, and Cochrane Library. The search initially yielded 676 potentially relevant studies, 14 of which were included in the final analysis. Of these 14 studies, 3 were classified as consensus statements or guidelines, 3 as observational studies, 2 as reviews, 5 as case reports, and 1 as an editorial. Most of the evidence regarding prophylactic treatment (eg, blood transfusion, replacement therapy, or medication administration) prior to endodontic therapy was derived from observational studies. The most frequently reported procedure was endodontic therapy, while 1 case report described a surgical endodontic procedure. Most studies included in the analysis reported that these procedures could be performed under local anesthesia. Two case reports and 1 observational study described complications after endodontic therapy in patients with IBDs. This scoping review revealed a lack of well-designed studies related to the topic of endodontic therapy in patients with IBDs. The available evidence suggests that endodontic therapy in patients with IBDs can be considered a low-risk procedure; local anesthesia should be used in most cases when patients with IBDs are treated, but the use of prophylactic measures is preferred when nerve block anesthesia is required; endodontic therapy can be conducted in a clinical setting without the need for hospital admittance; and, although the number of reported complications is small, the risk should not be ignored.

Reporting quality of scoping reviews in dental public health.

BACKGROUND: The study aimed to explore reporting characteristics of scoping reviews in dental public health and the impact of some factors on the reporting quality. METHODS: This study searched for dental public health scoping reviews in PubMed and Scopus without year restrictions and restricted to English-language publications. Study selection was undertaken by two reviewers independently. One reviewer, after training, extracted data from included studies considering general study characteristics and reporting characteristics. The impact of PRISMA-ScR publication, journal endorsement, and use of study protocol on the reporting was explored. RESULTS: Eighty-one scoping reviews were included. Five items presented rates of appropriate reporting higher than 80% considering the overall percentage. Related to the impact of PRISMA-ScR publication, six items were found more often in scoping reviews published after the publication of PRISMA-ScR than in scoping reviews published before the publication of PRISMA-ScR. With regards to journals endorsement, only two reporting characteristics were found more often in scoping reviews published in journals that endorse the PRISMA-ScR statement than in scoping reviews published in non-endorsers journals. Last, regarding the use of the pre-specified protocol, five reporting characteristics presented differences in studies reporting the use of pre-specified protocol than in studies that did not mention the use of a protocol. All differences were statistically significant. CONCLUSIONS: Important information is missing in the included scoping reviews demonstrating crucial reporting problems.

A Modified Technique for Induced Gingival Growth Around Compromised Teeth Prior to Implant Placement: A Report of Two Cases.

Regenerative and reconstructive periodontal plastic surgery are important options for treating marginal tissue recession and can be indicated for root coverage or periodontal procedures prior to implant placement. Among the available procedures, periodontal flaps with subepithelial connective tissue graft (CTG) is the most common treatment option to achieve proper tissue manipulation. The present study proposes a modification of a previous technique for inducing spontaneous gingival growth around teeth that will be extracted prior to implant placement, through successive reduction of the buccal root surface. This successive reduction of root surfaces is performed with diamond burs, and such reductions create space for the gingival tissue to grow coronally by reducing root convexity and, consequently, stimulating the healing process with the formation of granulation tissue that will then differentiate into keratinized tissue. The presented technique is suggested to improve the esthetic outcomes for cases involving tooth extraction, implant placement in the extraction socket, and immediate loading with interim restoration and CTG.

Assessment of Surgical and Radiographic Parameters for Abutment Height Selection: A Prospective Study with 1-Year Follow-up.

PURPOSE: The "one-abutment, one-time" concept entails the placement of a definitive abutment at the time of implant placement, without removal during prosthesis manufacture, with the aim to promote a safer environment for the peri-implant tissues. Identifying surgical and radiographic parameters that can assist with the abutment height selection would facilitate the adoption of the one-abutment, one-time concept. Therefore, the aim of this study was to assess the role of surgical and radiographic parameters as predictive factors for abutment height selection in implant-retained single crowns. MATERIALS AND METHODS: This prospective study assessed the role of surgical and radiographic measurements in the implant survival and success rates and marginal bone loss in implant-retained single crowns. Implants were placed in both healed sites and extraction sockets, and the distances between the implant platform and alveolar bone crest, implant platform and gingival margin, and buccal gap (when present) were recorded using a straight periodontal probe. Digital radiographs were made at implant placement (T0), abutment height selection (Ta), and 1-year follow-up (Tf), and the distance between the implant platform and the alveolar bone crest (mm) was assessed. Linear regression models and Pearson correlation were used to assess the influence of primary and secondary outcomes on abutment height. RESULTS: A total of 130 implants were placed in 68 patients. The mean surgical distance between the bone crest and the implant platform was 1.71 ± 1.01 mm, and the mean distance from the gingival margin to the implant platform was 3.94 ± 1.90 mm, while at the abutment selection appointment, the mean transmucosal height was 3.58 ± 1.50 mm. A high linear correlation was found between the selected abutment height and two primary outcomes: the radiographic implant platform to alveolar bone crest distance at T0 (r2 = 0.66; P < .001) and the transmucosal height at Ta (r2 = 0.81; P < .001). CONCLUSION: Radiographic measurements of the distance between the implant platform and the alveolar bone crest at implant placement can serve as an important parameter to select the abutment height for definitive restorations.

Delayed Bleeding in a Hemophilic Patient After Sinus Floor Elevation and Multiple Implant Placements: A Case Report.

Dental treatments in hemophilic patients are challenging, and the absence of adequate preparation for the procedures can be life-threatening. This letter describes a delayed postoperative bleeding after multiple dental implants with sinus floor elevation in a patient with mild hemophilia A.

Comparison of material properties and biofilm formation in interim single crowns obtained by 3D printing and conventional methods.

STATEMENT OF PROBLEM: Three-dimensionally printed interim restorations are among the recent technological advancements in dentistry. However, evidence of their performance is lacking. PURPOSE: The purpose of this in vitro study was to compare the properties of interim restorations made by 3D printing with different technologies, laser stereolithography (SLA), technology and selective laser sintering (SLS) with those obtained by conventional techniques from acrylic resin and bis-acryl resin. MATERIAL AND METHODS: Four different groups (acrylic resin, bis-acryl resin, SLS, SLA) were tested for flexural strength, Vickers microhardness, fatigue test, compressive strength, surface roughness before and after polishing, and biofilm formation. Specimens were made in the form of rectangular blocks, disks, and single crowns by following the manufacturing technique of each material. One-way ANOVA was used to test biofilm formation, Vickers microhardness, and the results of the 3-point bend flexural test, while the paired t test was used to assess differences in surface roughness between the materials (α=.05 for all tests). RESULTS: The highest Vickers microhardness value was for acrylic resin interim crowns, while the elastic moduli were lower for both the 3D printed materials. Only the SLA resin fractured during the fatigue test. For surface roughness, a statistically significant difference was found among the studied materials (P<.001), with SLA resin and bis-acryl resin having the lowest values. No statistically significant differences were found for biofilm formation (P>.05). CONCLUSIONS: SLS resin had favorable results for the Vickers microhardness, higher maximum flexural strength, and peak stress in load-to-fracture tests, the fatigue test, and biofilm formation compared with acrylic resin and bis-acryl resin, while SLA resin showed favorable results only for biofilm formation and surface roughness.

Influence of low-level laser therapy on implant stability in implants placed in healed sites: a randomized controlled trial.

BACKGROUND: The present study aims to assess the influence of low-level laser therapy (LLLT) on stability in implants placed in healed sites. MATERIAL AND METHODS: The present study followed the SPIRIT statement and is reported according to CONSORT. Patients were randomly allocated to LLLT or control groups. LLLT consisted in the application of 808-nm GaAlA laser applied before the preparation of the implant bed and after suturing (80 seconds; 11J/cm2). Implant stability quotient (ISQ) and the distance between the implant platform to the alveolar bone crest (millimeters) were assessed at implant placement (T0) and the abutment selection phase (4-6 months, Ta). RESULTS: A total of 64 implants were placed in 33 patients. The insertion torque ranged from 10 to 70 N.cm (mean 43.23; SD ±16.82). The T0 ISQ ranged from 18 to 95.5 (mean 61.7; SD ±18.23) and the crestal bone radiographic distance was 2.03 mm (SD±1.27). At Ta, the ISQ ranged from 39 to 90 (mean 64.2; SD±9.84), and the mean crestal bone radiographic loss was 1.70mm (SD±1.65). However, no differences were observed when LLLT and control groups were compared with ISQ difference (Ta-T0; p=0.598) or radiographical peri-implant alterations (p=0.531). CONCLUSION: LLLT did not influence the implant stability in implants placed in healed sites compared to a control group. TRIAL REGISTRATION: ReBEC, RBR-35TNJ7 . Registered May 23, 2018.

Impact of COVID-19 pandemic on oral health procedures provided by the Brazilian public health system: COVID-19 and oral health in Brazil.

OBJECTIVE: The objective of this study was to assess the number of dental procedures performed in the Brazilian Public Health System (SUS) during the first wave of COVID-19 in Brazil (1st semester of 2020) and compare it with the same period of 2019. METHODS: A retrospective study was conducted based on the SUS Dataset (DATASUS). Descriptive analysis of the number of dental procedures and socio-demographic regions was presented and the number of dental procedures during the first semester of 2020 was compared to 2019, using Wilcoxon Signed Rank Test (α = 0.05). The number of COVID-19 confirmed cases and deaths were also retrieved from DATASUS. RESULTS: Dental procedures decreased from 47 million in the first semester of 2019 to 15 million in 2020, representing an overall decrease of about 66%. Statistically significant differences were observed for the numbers of procedures regarding preventive actions related to oral health (-84.53%; p < 0.001), primary care (-60.69%; p < 0.001), endodontic specialized care (-52.50%; p < 0.001), and periodontal and oral surgery specialized care (-54.57%; p < 0.001). CONCLUSION: The COVID-19 pandemic also reduced by half the number of oral health procedures provided by the SUS in almost all Brazilian states regardless of whether these states had a large number of confirmed cases or deaths. Future policies are recommended in order to reduce the negative impact of the suspension of dental services on the oral health of the population.

The mass production of systematic reviews about COVID-19: An analysis of PROSPERO records.

OBJECTIVE: This study aimed to assess the characteristics of different designs of systematic reviews (SRs) registered in the International Prospective Register of Systematic Reviews (PROSPERO) about COVID-19. METHODS: The search was performed in the PROSPERO database using the strategy proposed by the database and considered only human studies. The last date of the search was April 27, 2020. Full text of all records was accessed, and data were extracted by a single researcher, which was further double-checked by another researcher. A descriptive analysis was performed considering record characteristics using tables. RESULTS: We included 564 records from which the vast majority were registered as SRs (n = 513, 91%). In general, we found poor reporting and missing or confusing information, since 84% of the records (n = 474) did not report the full search that would be adopted, 16% (n = 90) did not report clearly the databases that would be used, and 49.1% (n = 277) did not report the number of primary outcomes. The main focus of most of the records involved clinical, epidemiological, complication, and laboratory characteristics (n = 173, 30.7%) or the treatment of COVID-19 (n = 138, 24.5%). CONCLUSION: A large number of SRs about COVID-19 have been conducted, and many of the assessed records were poorly reported and would be difficult to replicate. Besides, collected data points to an epidemic of redundant reviews on COVID-19.

Preliminary validation of the Dental Clinical Learning Environment Instrument in a Brazilian dental school.

INTRODUCTION: This study aimed to perform a preliminary validation of the Dental Clinical Learning Environment Instrument (DECLEI) in a Brazilian dental school. MATERIAL AND METHODS: Dental Clinical Learning Environment Instrument was translated into Brazilian-Portuguese, and Brazilian DECLEI's items relevance and content validity were assessed using the content validity index (CVI). DECLEI was then distributed to 155 Brazilian undergraduate dental students attending the 7th and 8th semester of dental studies. Principal Component Analysis (PCA) was used as an initial exploration of the Brazilian DECLEI's internal structure. Item-total correlations for the remaining items were calculated to identify items with poor discrimination coefficients. The internal consistency reliability for the final set of 17 items was calculated using Cronbach's alpha coefficient. The sensitivity of the instrument to measure differences between groups regarding year in dental school, race and sex was also assessed. RESULTS: The CVI was ≥0.80 for all 24 items of the Brazilian DECLEI indicating that all items were relevant to the local culture. Principal Components Analysis (PCA) provided evidence of a single dominant component containing 17 items (Cronbach's α = .86), and all 17 items met the benchmark of acceptable item-total correlation. Significant differences were found only when comparing 7th- and 8th-semester students. CONCLUSIONS: Dental Clinical Learning Environment Instrument has the potential to be used as a reliable instrument to measure clinical learning environments for Brazilian dental students.

Inherited bleeding disorders in oral procedures. Assessment of prophylactic and therapeutic protocols: a scoping review.

BACKGROUND: This scoping review aimed to map available evidence regarding minor/major oral procedures in patients with inherited bleeding disorders (IBDs). METHODS: Studies in medicine or dentistry that reported minor and major oral procedures in individuals presenting IBDs (e.g. haemophilia A or B, von Willebrand disease) were selected. Search and screening were performed in PubMed/Medline, Scopus, Web of Science and Cochrane Library by two independent researchers. RESULTS: Initial search yielded 4152 citations, of which 257 were included in the final analysis. Most of the evidence for prophylaxis use was derived from observational studies and the most-commonly reported prophylactic protocols were fresh frozen plasma and factor VIII concentrate. A considerable number of studies reported postoperative complications and hospitalizations. CONCLUSION: The present study identified that (1) there is room for new studies to assess the use of antifibrinolytic agents with no factor replacement; (2) to date, the use of factor replacement therapy is the most indicated approach when treating patients with IBDs with adjunct systemic or local antifibrinolytic agents to reduce post-operative complications; and (3) there is a critical need for high-quality evidence studies since much of the conclusions of the included studies are not supported by statistical analysis.

Novel bendable abutments as a solution to correct unfavorable implant inclination. A clinical report.

OBJECTIVE: This clinical case report describes a novel bendable abutment as a prosthetic solution for implants presenting with an unfavorable inclination. CLINICAL CONSIDERATIONS: A metal-ceramic screw-retained single crown was made on this novel bendable abutment in a patient presenting with a pronounced buccal inclination of an implant. A plastic reference guide is used to define the correct inclination and then this inclination is transferred to the abutment using a specific bending device at the same appointment. CONCLUSIONS: Bendable abutments can be used as a solution to correct unfavorable implant inclinations. This abutment can be customized at the same appointment considering a case-specific inclination rather than conventional pre-angled abutments. CLINICAL SIGNIFICANCE: Bendable abutments can be customized according to each case specificities while conventional pre-angled abutments may not be adequate for all patients. Also, the abutment customization could be easily done by dentists at their own practices using a specific bending device with hand pressure only, saving time, and the need to order pre-angled abutments or having it in stock.

Influence of low-level laser therapy on implant stability in implants placed in fresh extraction sockets: A randomized clinical trial.

BACKGROUND: Low-level laser therapy (LLLT) has been suggested to improve primary stability at the early stages of osseointegration in animal models. However, there is still scarce evidence about its influence on implant stability in humans. PURPOSE: To assess the influence of LLLT on implant stability in implants placed in fresh extraction sockets. MATERIAL AND METHODS: A randomized controlled trial was designed according to the SPIRIT guidelines and is reported following the CONSORT. Patients were randomly allocated according to control or LLLT groups. LLLT consisted in the application of GaAlAs laser (808 nm, avg. power density: 50 mW, circular spot diameter and area: 0.71 cm/0.4cm2 ) applied in six points in contact mode with peri-implant soft tissue (1.23 minutes in each point of application; dose per point 11 J) before bone perforation and after suturing. The total dose resulted in 66 J per application moment. This LLLT protocol was applied only in the dental implant placement session. Implant stability was by ISQ at implant placement (T0 ) and the abutment selection (Ta ). Digital radiographs for T0 and Ta were used to assess the distance between the implant platform and alveolar bone crest, in millimeters. T-test and Shapiro-Wilk test were used to analyze data between groups using the implant as a unit of analysis. RESULTS: Fifty implants were placed in 44 patients. The insertion torque ranged from 15 to 60 N.cm (mean 35.64 ± 13.34). Two implants of the LLLT and one of the control groups were lost to follow-up and one implant of the control group failed to osseointegrate (4.3%). ISQ at T0 ranged from 17 to 79 (mean 59.33 ± 13.05) and from 40 to 89 (mean 66.46 SD ± 11.56) at Ta . No differences were observed when comparing the groups with ISQ difference (P = .433) or radiographical peri-implant alterations (P = .261). CONCLUSIONS: LLLT did not influence implant stability in implants placed in fresh extraction sockets when assessed at healing abutment installation.

Protocol registration improves reporting quality of systematic reviews in dentistry.

BACKGROUND: The aims of this study were to assess whether the previous registration of a systematic review (SR) is associated with the improvement of the quality of the report of SRs and whether SR registration reduced outcome reporting bias. METHODS: We performed a search in PubMed for SRs in dentistry indexed in 2017. Data related to SR registration and reporting characteristics were extracted. We analyzed if the reporting of 21 characteristics of included SRs was associated with the prospective registration of protocols or reporting of a previously established protocol. The association between prospective registering of protocols, reporting of funding and number of included studies versus outcome reporting bias was tested via multivariable logistic regression. RESULTS: We included 495 SRs. One hundred and 62 (32.7%) SRs reported registering the SR protocol or working from a previously established protocol. Thirteen reporting characteristics were described statistically significant in SRs registered versus SRs that were not. Publication bias assessment and Report the number of participants showed the highest effects favoring the register (RR 1.59, CI 95% 1.19-2.12; RR 1.58, CI 95% 1.31-1.92 respectively). Moreover, Registration was not significantly linked with the articles' reporting statistical significance (OR 0.96, CI 95% 0.49-1.90). CONCLUSION: There is a positive influence of previously registering a protocol in the final report quality of SRs in dentistry. However, we did not observe an association between protocol registration and reduction in outcome reporting bias.

Assessment of stress/strain in dental implants and abutments of alternative materials compared to conventional titanium alloy-3D non-linear finite element analysis.

The aim of this study was to assess the stress/strain in dental implant/abutments with alternative materials, in implants with different microgeometry, through finite element analysis (FEA). Three-dimensional models were created to simulate the clinical situation of replacement of a maxillary central incisor with implants, in a type III bone, with a provisional single crown, loaded with 100 N in a perpendicular direction. The FEA parameters studied were: implant materials-titanium, porous titanium, titanium-zirconia, zirconia, reinforced fiberglass composite (RFC), and polyetheretherketone (PEEK); and abutment materials-titanium, zirconia, RFC, and PEEK; implant macrogeometry-tapered of trapezoidal threads (TTT) and cylindrical of triangular threads (CTT) (ø4.3 mm × 11 mm). Microstrain, von Mises, shear, and maximum and minimum principal stresses in the structures and in peri-implant bone were compared. There was increased stress and strain in peri-implant bone tissue caused by implants of materials with lower elastic modulus (mainly for PEEK and RFC). They also presented higher concentration of stresses in the implant itself (especially RFC). Zirconia implants led to lower stress and strains in peri-implant bone tissue. Less rigid abutments (RFC and PEEK) associated with titanium implants led to higher stress in the implant and in peri-implant bone tissue. The TTT macrogeometry showed a higher stress concentration in the implant and peri-implant bone tissue. The stress/strain in peri-implant bone tissue and implant structures were affected by the material used, where reduced values were caused by stiffer materials. Lower stress/strain values were obtained with cylindrical implants of triangular treads.

Influence of Implant Inclination and Prosthetic Abutment Type on the Biomechanics of Implant-Supported Fixed Partial Dentures.

Obtaining parallelism during implant placement is often difficult, leading to inclination of implants. The present study evaluated the stress distribution in 3-unit fixed partial dentures supported by 2 implants with different inclinations and prosthetic abutments. Universal castable long abutments (UCLAs) or tapered abutments were used considering 17° of implant angulation in different directions (mesial, distal, buccal, or lingual). To do so, 3-dimensional finite element models were built and exported to specific analysis software. Forces were applied to the functional cusps. Data were obtained with regard to the maximum principal and von Mises stresses (in MPa). No relevant differences were observed in the stress values in the cortical and cancellous bone nor in the prosthesis with UCLA or tapered abutments. However, a relevant stress reduction in the prosthetic screws of the tilted implant was observed when using UCLA abutments. According to the obtained results, it is possible to suggest that both UCLA or tapered abutments can be used for 3-unit fixed partial dentures when 1 of the implants is tilted. UCLA abutment might lead to less biomechanical problems related to screw loosening or fracture.

Industry sponsorship bias in clinical trials in implant dentistry: Systematic review and meta-regression.

AIM: Industry sponsorship might distort the conduct and findings of studies in a large range of medical disciplines. The objective of this study was to assess whether industry sponsorship bias is present in randomized controlled trials (RCTs) on dental implants. MATERIAL AND METHODS: Two databases were searched (MEDLINE; Web of Science) to identify RCTs published between 1996 and 2016 assessing different implant systems, components or techniques, such as implant-abutment connections, geometries, surfaces, loading protocols or regions of placement. Studies' sponsorship status was classified as unclear, non-sponsored or sponsored. Our outcome was marginal bone loss per year (MBL/year) of follow-up. Random-effects meta-analysis of MBL/year with subgroup analysis according to sponsorship status was performed. Moreover, multivariable stepwise-selection meta-regression was performed to assess whether sponsorship status, among other covariates, was associated with MBL/year. RESULTS: One hundred and two RCTs (4,775 patients, 8,806 implants) were included. Overall mean (95% confidence interval) MBL/year was 0.74 mm (95% CI 0.67/0.82). There was no significant difference in MBL/year among sponsorship categories; unclear: 0.64 (95% CI 0.37/0.91); non-sponsored: 0.65 (095% CI 0.55/0.75); and sponsored: 0.82 (95% CI 0.71/0.94). CONCLUSION: Meta-regression did not demonstrate a significant association of MBL/year with sponsorship status or other covariates was found. We did not detect significant sponsorship bias in RCTs on dental implants.

Influence of Different Implant Geometry in Clinical Longevity and Maintenance of Marginal Bone: A Systematic Review.

PURPOSE: To assess, through a systematic review, the influence of different implant geometries on clinical longevity and maintenance of marginal bone tissue. METHODS: An electronic search was conducted in MEDLINE, Scopus, and Web of Science databases, limited to studies written in English from 1996 to 2017 using specific search strategies. Only randomized controlled trials (RCTs) that compared dental implants and their geometries were included. Two reviewers independently selected studies, extracted data, and assessed the risk of bias of included studies. RESULTS: From the 4006 references identified by the search, 24 were considered eligible for full-text analysis, after which 10 studies were included in this review. A similar behavior of marginal bone loss between tapered and cylindrical geometries was observed; however, implants that had micro-threads in the neck presented a slight decrease of marginal bone loss compared to implants with straight or smooth neck. Success and survival rates were high, with cylindrical implants presenting higher success and survival rates than tapered ones. CONCLUSIONS: Implant geometry seems to have little influence on marginal bone loss (MBL) and survival and success rates after 1 year of implant placement; however, the evidence in this systematic review was classified as very low due to limitations such as study design, sample size, and publication bias. Thus, more well-designed RCTs should be conducted to provide evidence regarding the influence of implant geometry on MBL and survival and success rates after 1 year of implant placement.

Stress distribution in cylindrical and conical implants under rotational micromovement with different boundary conditions and bone properties: 3-D FEA.

Factors related to micromovements at bone-implant interface have been studied because they are considered adverse to osseointegration. Simplifications are commonly observed in these FEA evaluations. The aim of this study was to clarify the influence of FEA parameters (boundary conditions and bone properties) on the stress distribution in peri-implant bone tissue when micromovements are simulated in implants with different geometries. Three-dimensional models of an anterior section of the jaw with cylindrical or conical titanium implants (4.1 mm in width and 11 mm in length) were created. Micromovement (50, 150, or 250 µm) was applied to the implant. The FEA parameters studied were linear vs. non-linear analyses, isotropic vs. orthogonal anisotropic bone, friction coefficient (0.3) vs. frictionless bone-implant contact. Data from von Mises, shear, maximum, and minimum principal stresses in the peri-implant bone tissue were compared. Linear analyses presented a relevant increase of the stress values, regardless of the bone properties. Frictionless contact reduced the stress values in non-linear analysis. Isotropic bone presented lower stress than orthogonal anisotropic. Conical implants behave better, in regard to compressive stresses (minimum principal), than cylindrical ones, except for nonlinear analyses when micromovement of 150 and 250 µm were simulated. The stress values raised as the micromovement amplitude increased. Non-linear analysis, presence of frictional contact and orthogonal anisotropic bone, evaluated through maximum and minimum principal stress should be used as FEA parameters for implant-micromovement studies.