Characteristics and Risk Factors for the Fracture of One-Piece Implants.

Objective: The one-piece dental implant was originally designed to overcome the structural weaknesses of the two-piece implant. However, a fractured one-piece implant requires removal because the abutment cannot be repaired or replaced to support new prosthetic restorations. The aim of this study was to clarify the features and risk factors for fracture of the one-piece implant. Methods: This study was designed as a retrospective case series research. The subjects were patients who were treated for fractures of the one-piece implant at a clinic in Japan between 2012 and 2021. Fractures of the one-piece implant were diagnosed by cone-beam computed tomography, and the association between age and duration from implant placement to fracture was analyzed by one-way ANOVA followed by the Tukey test. Results: Eighteen patients and 20 one-piece implants (under 39 years: 5 patients and 6 implants; 40-59 years: 7 patients and 7 implants; over 60 years: 6 patients and 7 implants) had fractures in their one-piece implants. Of the fractured implants, 11 had a diameter of 3 mm, and 9 had a diameter of 4 mm. The mean durations up to implant fracture were 662 days in the younger group, 1467 days in the middle group, and 1239 days in older group, and the duration was significantly shorter in the younger group. In addition, 83.3% of fracture implants in the younger group were in the molar region. All fractures of the one-piece implants occurred under the bone margin. Two patients had torus mandibularis, and 1 patient was had bruxism. Conclusions: One-piece implants in younger patients that are located in the lower molar position are the most susceptible to implant fracture, and the fracture occurred under the bone margin in all cases.

Tooth-Implant-Supported Prosthetic Structures Versus Implant-Supported Restorations.

Objectives: The primary aim was to compare the amount of bone height change that occurs around the tooth and the implant when having tooth-implant-supported prosthetic restorations versus bone height change that appears around implants in only implant-supported prosthetic restorations. The secondary aim was to examine the influence of various factors such as the number of teeth involved in the construction, their endodontic treatment, number of implants, the type of implantology construction, the jaw in which the construction is located, the condition of the opposite jaw, gender, age, and working time, as well as to examine whether the initial bone level influenced the amount of change in bone height itself. Materials and methods: With a total of 50 respondents, 25 X-ray panoramic images were representing tooth-implant-supported prosthetic restorations, while the other 25 were representing implant-supported prosthetic restorations. Bone measures were taken (from enamel-cement junction/implant neck to the most apical bone point) from 2 panoramic radiographs. The first one is immediately after the implant placement and the second and the last one again in half a year up to seven years after, depending on the time when the photo was taken for each patient. The obtained difference represented the bone resorption, the bone formation, or a state without change. Influence of different factors, such as sex, age of the patient, working time, the number of teeth involved in the construction, endodontic treatment, number of implants, the type of implant construction, the jaw where the construction is located, the condition of the opposite jaw, as well as the initial bone condition, was examined. During the statistical analysis, frequency tables, basic statistical parameters, the Mann-Whitney U test, the Kruskal-Wallis Anova, Wilcoxon test, and regression analysis were used, and the results were presented in tabular form and the form of the Pareto diagram of t-values. Results: No statistically significant difference in bone change (whether we are talking about the place of the implant (-0.359±1.009 and median value 0.000), the place of a tooth (-0.428±0.746 and median value -0,150) in tooth-implant supported restorations, or the place of the implant in case of implant-supported structures (-0,059±0,200 and median value -0,120)) was proven. When talking about the influence of other factors, by regression analysis, the number of implants was shown to be the only factor with a statistically significant influence (ß=0.54; P=0.019) in a change of bone level, but only when talking about implant-supported restorations. Conclusion: No significant difference was proven between bone height change, neither around the tooth nor the implant in tooth-implant-supported prosthetic restorations compared to the bone height changes around the implant in only implant-supported prosthetic restorations. Among all the examined factors, the number of implants has shown to have statistically significant contribution to the amount of bone height change in implant-supported prosthetic restorations.

Oral Rehabilitation of a Patient with Papillon Lefèvre Syndrome Using Fixed Full-Arch Hybrid Prostheses Supported by Four Axially Loaded Implants: A Case Report with Four-Year Follow-up.

This report details the successful prosthetic rehabilitation of a 25-year-old male patient with Papillon Lefèvre Syndrome (PLS) using an implant-supported hybrid prosthesis. Six implants were placed in the maxilla, and four were placed in the mandibular arch. All implants were inserted axially (non-tilted) and were planned to be loaded after a healing period of 6 months. One implant failed due to graft loss during the healing phase, which was removed and the remaining implants were restored with a hybrid prosthesis after 6 months, using the delayed loading protocol. The patient was followed-up for four years and all the remaining implants successfully integrated and remained fully functional during this period. The prosthesis significantly improved the functional, aesthetic, and psychological well-being of the patient. This case report is the first of its kind to use only four axially placed implants for rehabilitation of a PLS patient with a successful four-year follow-up.

Influence of diameter in the stress distribution of extra-short dental implants under axial and oblique load: a finite element analysis

Aim: This study evaluated the influence of a wide diameter on extra-short dental implant stress distribution as a retainer for single implant-supported crowns in the atrophic mandible posterior region under axial and oblique load. Methods: Four 3D digital casts of an atrophic mandible, with a single implant-retained crown with a 3:1 crown-to-implant ratio, were created for finite element analysis. The implant diameter used was either 4 mm (regular) or 6 mm (wide), both with 5 mm length. A 200 N axial or 30º oblique load was applied to the mandibular right first molar occlusal surface. The equivalent von Mises stress was recorded for the abutment and implant, minimum principal stress, and maximum shear stress for cortical and cancellous bone. Results: Oblique load increased the stress in all components when compared to axial load. Wide diameter implants showed a decrease of von Mises stress around 40% in both load directions at the implant, and an increase of at least 3.6% at the abutment. Wide diameter implants exhibited better results for cancellous bone in both angulations. However, in the cortical bone, the minimum principal stress was at least 66% greater for wide than regular diameter implants, and the maximum shear stress was more than 100% greater. Conclusion: Extra-short dental implants with wide diameter result in better biomechanical behavior for the implant, but the implications of a potential risk of overloading the cortical bone and bone loss over time, mainly under oblique load, should be investigated

Implant digital impression accuracy using extraoral scanners: a three-dimensional analysis

Aim: To analyze the accuracy of extraoral systems (Ceramill Map400+, AutoScan-DS200+, and E2) in full implantprosthetic rehabilitation three-dimensionally. Methods: A metallic edentulous maxilla with four implants was digitalized by a contact scanner (MDX-40 - Roland, control) and used as a control image to compare with other images generated by three laboratory scanners (10 samples per group). Letters identified all the four components: A and D angled 45º, and B and C parallel. The BioCAD software exported the images (.STL) to compare and verify deviations of the analogs on the X, Y, and Z axes. The nonparametric Kruskal-Wallis test and the two-way ANOVA on ranks with a post hoc Tukey test analyzed the data with 5% significance. Results: No statistical differences were observed in the accuracy between the extraoral scanners (p=0.0806). However, when analyzing only the components, component D was more accurate when scanned with Ceramill Map400+ compared with AutoScan DS200+ (p<0.001) and with E2 (p=0.002). Conclusions: All extraoral systems assessed showed digitalization accuracy but with more deviations in angled implants. The Ceramill Map400+ scanner showed the best results for the digital impression of a complete arch

Clinical performance of implant supported mandibular overdentures with cantilever bar and stud attachments: A retrospective study.

BACKGROUND: Treatment of edentulous patients with implant-supported over-dentures improves denture's retention and stability. Published data concerning implant-supported overdenture with cantilever bars that claimed that can affect the survival and bone loss of implants are scarce. PURPOSE: The purpose of this study was to evaluate 5-year clinical performance of mandibular implant-supported over-dentures with different attachment systems. MATERIALS AND METHODS: In this retrospective study, 103 patients who had received mandibular over-dentures supported by two implants were evaluated in a 5-year follow up. Studied groups were patients with Spherblock ball attachment (58 patients), Dolder bar with cantilever (36 patients), and Locator attachment (9 patients). Marginal bone-loss around implants, prosthetic complications, soft tissue status of the implants (gingival index, plaque index, pocket depth, and bleeding on probing) were used to compare studied groups. Visual Analogue Scale (VAS) criteria was used to assay patient's satisfaction. One-way ANOVA, Scheffe, Kruskal-Wallis, Mann-Whitney, and Fisher's exact tests, were used for the data analysis (α = 0.05). RESULTS: One hundred and three patients (46 male, 57 female, mean age 64.7 ± 8.6) with 206 implants (Strauman) were studied. The implant survival rate was 100% with mean bone loss of 0.22 mm around implants in 5 years. Prosthetic complications including attachment wear and denture fracture occurred more often with ball attachments. The number of attachment replacement, and post insertion appointments were significantly less in patients with bar attachments (p < 0.05). Pocket depth and gingival index were less in the ball attachment (p < 0.05). CONCLUSION: Mandibular overdenture supported by two implants can be considered a successful treatment in edentulous patients. The frequency of prosthetic complication is higher in unsplinted than splinted superstructures.

Does the Use of Surface Electromyography Could Improve Quality of Life among Patients Rehabilitated by Mandibular Overdentures on Different Attachments?

Abstract Objective: To analyze and compare changes of quality of life parameter among dental patients rehabilitated by the implant-supported overdentures with different attachment systems. Material and Methods: Forty-eight patients were recruited as a study cohort. The implant placement procedure was based on the results obtained by CBCT scanning and individualized surgical templates manufactured for correct implant placement. Each individual received two k3Pro Implants (Sure Type with 4.0 or 4.5 mm in diameter) at the intraforaminal area due to standard protocol of implantation provided by the manufacturer under local anesthesia. All patients were distributed between two groups based on the fact of using either Locator- or ball-attachments. Rank correlation was measured using Spearman correlation coefficient, while linear correlation was evaluated by Pearson correlation coefficient. Results: No statistically meaningful differences were noted regarding patients' distribution among groups considering age (p>0.05) and gender (p>0.05). Provided patient-level analysis demonstrated that increase of conventional full denture service time was positively correlated with escalation of OHIP-EDENT scores. The most prominent inter-correspondences were noted specifically between longevity of denture service and elevation of scores within "Functional limitation" (r=0.61; p<0.05), "Physical pain" (r=0.51; p<0.05) and "Physical disability" (r=0.57; p<0.05) subdomains. No statistically argumented regressions were noted between increase tendency of OHIP-EDENT scores and gender (p>0.05) or age (p>0.05) parameters. Conclusion: Significant improvements of quality of life measured with OHIP-EDENT were noted for both types of attachments compared to the pre-treatment situation independently of additionally provided surface electromyography-based alignment.

Bone evaluation of single edentulous areas of maxilla: short communication / Avaliação óssea de regiões maxilares candidatas à reabilitação unitária implantossuportada: uma comunicação curta

Objective: Evaluate the height and bone thickness in healed sites of single implant areas. Materials and Methods:In this cross-sectional study, cone-beam computed tomography (CBCT) images of single edentulous areas of maxilla of patients who needed aesthetic single implant rehabilitations were evaluated for measure the height and thickness using an implant planning software. Data were statistically analyzed using the Mann-Whitney and Pearson correlation test, considering the time, reason and region of tooth loss. For all tests, a p-value <0.05 was considered significant. Results: 48 patients with single tooth loss were included. The statistical analysis demonstrated that reason for the loss was not related to height or bone thickness. Bone thickness was statis-tical significant higher in the posterior region. For the anterior region, the bone thickness was significantly higher when the tooth was lost within 5 years. Pearson correlation test showed a moderate negative signifi-cant correlation between time of tooth loss and bone thickness in anterior region. Conclusion: Reason for tooth loss had no influence on the bone measurements of the residual ridge. In contrast, bone thickness may vary according to the region of tooth loss. The time of tooth loss and bone thickness in the anterior region were inversely proportional. Registration number at https://ensaiosclinicos.gov.br/rg/RBR-5cnyjj.

Objetivo: Avaliar a altura e espessura óssea em sítios unitários cicatrizados. Materiais e Métodos: Neste estudo transversal, imagens de tomografia computa-dorizada de feixe cônico (TCFC) de regiões edêntulas unitárias maxilares de pacientes candidatos a reabilitação unitária implantossuportada foram mensuradas em relação à altura e espessura óssea usando um software de planejamento de implante. Os dados foram analisados estatisticamente por meio do teste Mann-Whitney e de correlação de Pearson, considerando o tempo, o motivo e região da perda dentária. Para todos os testes, um valor de p <0,05 foi considerado significativo. Resultados: Foram incluídos 48 pacientes com perda dentária unitária. A análise estatística demonstrou que o motivo da perda dentária não influenciou na altura ou na espessura óssea. A espessura óssea foi estatisticamente maior na região posterior. Para a região anterior, a espessura óssea foi significativamente maior quando o dente foi perdido em até 5 anos. O teste de correlação de Pearson demonstrou uma correlação significativa negativa moderada entre o tempo de perda do dente e a espessura óssea na região anterior. Conclusão: O motivo da perda dentária não influenciou nas medidas ósseas do rebordo residual. Em contraste, a espessura do osso pode variar de acordo com a região da perda dentária. O tempo de perda dentária e a espessura óssea da região anterior foram inversamente proporcionais. Número de registro em https://ensaiosclinicos.gov.br/rg/RBR-5cnyjj

Marginal misfit of heat-pressed milled wax-pattern and CAD/CAM crowns and its effect on stress distribution in implant-supported rehabilitations

Aim: To compare the marginal fit of lithium disilicate CAD/CAM crowns and heat-pressed crowns fabricated using milled wax patterns, and evaluate its effect on stress distribution in implantsupported rehabilitation. Methods: A CAD model of a mandibular first molar was designed, and 16 lithium disilicate crowns (8/group) were obtained. The crown-prosthetic abutment set was evaluated in a scanning electron microscopy. The mean misfit for each group was recorded and evaluated using Student's t-test. For in silico analysis, a virtual cement thickness was designed for the two misfit values found previously, and the CAD model was assembled on an implant-abutment set. A load of 100 N was applied at 30° on the central fossa, and the equivalent stress was calculated for the crown, titanium components, bone, and resin cement layer. Results: The CAD/CAM group presented a significantly (p=0.0068) higher misfit (64.99±18.73 µm) than the heat-pressed group (37.64±15.66 µm). In silico results showed that the heat-pressed group presented a decrease in stress concentration of 61% in the crown and 21% in the cement. In addition, a decrease of 14.5% and an increase of 7.8% in the stress for the prosthetic abutment and implant, respectively, was recorded. For the cortical and cancellous bone, a slight increase in stress occurred with an increase in the cement layer thickness of 5.9% and 5.7%, respectively. Conclusion: The milling of wax patterns for subsequent inclusion and obtaining heat-pressed crowns is an option to obtain restorations with an excellent marginal fit and better stress distribution throughout the implant-abutment set

Prosthetic dental management of a patient with anhidrotic ectodermal dysplasia: a case report / Manejo protésico dental de un paciente con displasia ectodérmica anhidrótica: reporte de caso

Introduction: Ectodermal dysplasia (ED) comprises a broad group of genetic disorders characterized by alterations of the structures derived from the ectoderm, including those of the stomatognathic system. Case Report: The present article aims to report the prosthetic management of a patient with anhidrotic ectodermal dysplasia. A male patient diagnosed with ED who attended the dental consultation displaying oligodontia; underdeveloped alveolar ridges were observed. Results: The established treatment consisted of the adaptation of implant-supported fixed full-arch prosthesis designed through CAD-CAM technology for the lower jaw and of a removable partial prosthesis with muco-dental support for the upper jaw. The dental approach of patients with ED is based on a correct analysis of the facial characteristics and stomatological conditions of each subject. Conclusion: A multidisciplinary approach is mandatory due to the biological and functional complexity in biomechanical terms of these individuals.

Introducción: La displasia ectodérmica (DE) comprende un amplio grupo de trastornos genéticos caracterizados por alteraciones de las estructuras derivadas del ectodermo, incluidas las del sistema estomatognático. Reporte de Caso: El presente artículo tiene como objetivo informar del manejo protésico de un paciente con displasia ectodérmica anhidrótica. Paciente varón diagnosticado de DE acudió a consulta odontológica por oligodoncia; Se observaron crestas alveolares subdesarrolladas. Resultados: El tratamiento establecido consistió en la adaptación de una prótesis de arcada completa fija implantosoportada diseñada mediante tecnología CAD-CAM para el maxilar inferior y de una prótesis parcial removible con soporte muco-dental para el maxilar superior. El abordaje odontológico de los pacientes con DE se basa en un correcto análisis de las características faciales y condiciones estomatológicas de cada sujeto. Conclusión: Un enfoque multidisciplinario es obligatorio debido a la complejidad biológica y funcional en términos biomecánicos de estos individuos.

Three-dimensional finite element analysis of buccally cantilevered implant-supported prostheses in a severely resorbed mandible.

PURPOSE: The aim of the study was to compare the lingualized implant placement creating a buccal cantilever with prosthetic-driven implant placement exhibiting excessive crown-to-implant ratio. MATERIALS AND METHODS: Based on patient's CT scan data, two finite element models were created. Both models were composed of the severely resorbed posterior mandible with first premolar and second molar and missing second premolar and first molar, a two-unit prosthesis supported by two implants. The differences were in implants position and crown-to-implant ratio; lingualized implants creating lingually overcontoured prosthesis (Model CP2) and prosthetic-driven implants creatingan excessive crown-to-implant ratio (Model PD2). A screw preload of 466.4 N and a buccal occlusal load of 262 N were applied. The contacts between the implant components were set to a frictional contact with a friction coefficient of 0.3. The maximum von Mises stress and strain and maximum equivalent plastic strain were analyzed and compared, as well as volumes of the materials under specified stress and strain ranges. RESULTS: The results revealed that the highest maximum von Mises stress in each model was 1091 MPa for CP2 and 1085 MPa for PD2. In the cortical bone, CP2 showed a lower peak stress and a similar peak strain. Besides, volume calculation confirmed that CP2 presented lower volumes undergoing stress and strain. The stresses in implant components were slightly lower in value in PD2. However, CP2 exhibited a noticeably higher plastic strain. CONCLUSION: Prosthetic-driven implant placement might biomechanically be more advantageous than bone quantity-based implant placement that creates a buccal cantilever.

How the initial retentive force of implant-supported overdentures can be affected with splinted and unsplinted attachments systems.

Background: The aim of this study was to evaluate the retention of implant-supported overdentures with different attachment systems. Materials and Methods: In this in vitro study edentulous model with 2 Straumann implant in symphyseal region was used to make an overdenture with different attachment systems. (Dolder bar with 1 and 3 metal clips, Hader bar with 1 and 3 plastic clips, ball on bar with 2 and 4 plastic caps, Locator, Rhein plastic caps and Eleptical matrix). Retention values were recorded by universal testing machine with a cross speed of 50.8 mm/min in vertical, posteroanterior, and lateral direction. Repeated measure ANOVA and Duncan tests were used for the data analysis (α =0.05). Results: There was a statistically significant difference between the retention values of studied attachments in different dislodgment directions (P < 0.05). The highest and lowest retention were recorded for 4 balls on bar (56.71 N) and Rhein pink caps (27.89 N) in the vertical direction. Three metal clips (61.43 N) and Rhein pink cap (24.77 had the highest and lowest retention force in the posteroanterior direction. In the lateral direction, 4 balls on bar (62.68 N) and 1 plastic clip (32.27 N) showed the highest and lowest retention, respectively. Conclusion: If the higher retention force has been considered for implant-supported overdenture attachment selection, the clinician can use splinted bar or ball on bar superstructure.

Complicações precoces em próteses parciais fixas implantossuportadas de zircônia monolítica e bicamada: estudo prospectivo, randomizado, de boca dividida / Early complications in fixed partial prosthesis implants supported with monolithic and bilayer zirconia: a prospective, randomized, split-mouth study

As coroas de cerâmica pura estão ganhando força na odontologia uma vez que as exigências estéticas e mecânicas são cada vez mais evidentes, uma vez que as próteses metal free do tipo bicamada, não raramente, apresentam lascamento da cerâmica de cobertura como a principal falha a longo prazo, então iniciou-se o uso de próteses monolíticas. Paralelamente é crescente a busca e o uso de implantes osseointegráveis para suportar as reabilitações parciais, sendo a primeira opção para as reabilitações orais de áreas edêntulas. Logo, o objetivo deste estudo clínico prospectivo, randomizado de boca dividida é avaliar o desempenho clínico e a previsibilidade, caracterizando o número e o tipo de complicações e falhas precoces como desgaste do antagonista, perda óssea, inflamação gengival e falhas mecânicas que possam ocorrer em PPFs de três elementos implantossuportadas com retenção mista em região posterior de mandíbula em zircônia monolítica e infraestrutura de zircônia com cerâmica de cobertura, além de avaliar a percepção estética e satisfação do paciente com cada uma delas. Os pacientes selecionados (N=2) passarão por procedimentos cirúrgicos para instalação de dois implantes na região posterior de mandíbula, sendo dois de cada lado. Após três a quatro meses os cicatrizadores serão instalados e a moldagem será realizada para confecção das próteses seguindo a aleatorização do lado da mandíbula. Serão avaliados desgaste das próteses e dos antagonistas por meio de microscopia eletrônica de varredura; perda óssea periimplantar utilizando radiografias periapicais em três períodos, imediatamente após a instalação das próteses, uma semana após e três meses depois, percepção estética e alteração de cor utilizando o método de escala visual analógica pelo paciente. As hipóteses deste estudo são resistência à fratura e lascamento será semelhante nos grupos avaliados, todos os grupos serão esticamente aceitáveis, o desgaste do antagonista e das próteses será semelhante entre os grupos e a manutenção periodontal e nível de perda óssea será semelhante para os grupos(AU)

The pure ceramic crowns have been gaining strength in dentistry since the aesthetic and mechanical requirements are increasingly evident. Since free metal dentures of the bilayer type, not infrequently, show sputtering of the ceramic cover as the main long-term failure, the use of monolithic prostheses was started. At the same time, the search for and use of osseointegratable implants to support partial rehabilitation is increasing, being the first option for oral rehabilitation of edentulous areas. Therefore, the purpose of this prospective, randomized, split-mouth clinical study is to assess clinical performance and predictability, characterizing the number and type of early complications and failures such as antagonist wear, bone loss, gingival inflammation, and mechanical failures that may occur in PPFs of three implant - supported elements with mixed retention in posterior region of mandible in monolithic zirconia, zirconia infrastructure with covering ceramics and metaloceramics, besides evaluating aesthetic perception and patient satisfaction with each one. Patients selected (n = 8) will undergo surgical procedures to install two implants in the posterior mandible, two on each side. After three to four months the healing will be installed and the molding will be performed to make the prosthesis following the randomization of both the patients and the side of the jaw. Wear of prostheses and antagonists will be assessed by scanning electron microscopy and profilometry; bone loss peri-implant using periapical radiographs in seven periods, immediately after the implant installation, 7 days after surgery, before the installation of the healers, at the installation of the prosthesis, 21 days after, six and twelve months later, aesthetic perception and color change using the method of visual analog scale by the patient and an intraoral spectophotometer. The hypotheses of this study are resistance to fracture and chipping will be similar in the evaluated groups, all groups will be ethically acceptable, the wear of the antagonist and the prostheses will be similar between groups and the periodontal maintenance and level of bone loss will be similar for the groups(AU)

Screwed and cement implant prosthesis: current clinical considerations / Prótese sobre implante cimentada e parafusada: considerações clínicas atuais

ABSTRACT Introduction: There is no consensus as to which cemented or screwed retention system is best to avoid bone loss around the implant from a fixed implant-supported restoration. Objective: To evaluate the prosthesis retention systems on screw and cemented implants, regarding: bone loss, survival and failure rate, biological complications and microbiological analysis. Methods: A search was made for scientific articles that contemplated the subject through the databases Pubmed and SciELO, without period restriction. The titles, abstracts and then access to the full text has been verified. Results: It was found that excess cement may play an important role in the development of peri-implant disease. Technical failures are most seen in prosthesis retained by screws, and biological complications in cemented crowns. The success rate for both restraint systems is high, and retention-independent implant prosthesis treatment provides predictability. Conclusion: The appropriate retention system for the patient depends on several factors, including indication, advantages and disadvantages, retention provided, aesthetics and clinical performance.

RESUMO Introdução: Não há consenso sobre qual sistema de retenção, cimentado ou parafusado, é o melhor para evitar perda óssea ao redor do implante de uma restauração fixa implanto-suportada. Objetivo: Avaliar os sistemas de retenção de próteses sobre implantes parafusadas e cimentadas, quanto aos fatores: perda óssea, taxa de sobrevivência e de falhas, complicações biológicas e análises microbiológicas. Métodos: Foi realizada uma busca por artigos científicos que contemplassem o tema através das bases de dados Pubmed e SciELO, sem restrição de período. Os títulos, resumos e em seguida o acesso ao texto completo foi verificado. Resultados: Foi observado que o excesso de cimento pode desempenhar um papel importante no desenvolvimento da doença peri-implantar. Falhas técnicas são mais observadas em próteses retidas por parafusos e complicações biológicas em coroas cimentadas. A taxa de sucesso para os dois sistemas de retenção é alta e o tratamento com próteses sobre implantes independente da retenção oferece previsibilidade ao caso. Conclusão: O sistema de retenção apropriado para o paciente depende de diversos fatores, incluindo a indicação, vantagens e desvantagens, retenção fornecida, estética e desempenho clínico.

Peri-Implant Diseases and Biologic Complications at Implant-Supported Fixed Dental Prostheses in Partially Edentulous Patients.

PURPOSE: This is a single center, retrospective study to assess the prevalence of peri-implant disease and biologic complications in a cohort of partially edentulous subjects in relation to selected prosthetic factors. MATERIALS AND METHODS: Subjects previously treated with one or more implant-supported fixed dental prosthesis (ISFDPs) were recalled for a comprehensive examination. Clinical and radiographic records were taken and questionnaires were administered. The prevalence of implant failure, peri-implant disease and other biologic complications were correlated with selected prosthetic, clinical and patient-related factors using chi-square and multiple regression analyses. RESULTS: A convenience sample of 71 subjects with 100 prostheses supported by 222 dental implants were enrolled in the study. The mean follow-up time after prosthesis delivery was 3.3 ± 1.5 years (range of 1-9 years). The cumulative implant survival rate was 99.1%. Peri-implantitis was the most frequent major biologic complication (5% of implants), while the most frequent minor biologic complication was peri-implant mucositis (84.10% of implants). A diagnosis of peri-implant mucositis was more likely associated with cement-retained prostheses compared to screw-retained prostheses (OR 6.8, 95% CI 1.1-78.6, p = 0.045) and for short-span prostheses (≤3 prosthetic units) (OR 2.3, 95% CI 1.1-5.0, p = 0.034). Subject-reported quality of life measures were high regardless of the existence of major and/or minor complications, but decreased with increasing number of minor and total biologic complications. CONCLUSIONS: Peri-implant mucositis and other minor biologic complications were highly prevalent. The distribution of the observed complications differed based on the method of prosthesis retention and the number of prosthetic units replaced.

Vertical Marginal Discrepancy of Retrievable Cement/Screw-retained Design and Cement-retained Implant-supported Single Metal Copings.

AIM: To compare the vertical marginal discrepancy of retrievable cement/screw-retained design (RCSRD) and cement-retained (CR) implant-supported single metal copings cemented on implant abutments. MATERIALS AND METHODS: Single metal copings were fabricated for 20 4.5 × 10 mm titanium dental implants. Two groups of 10 implants each were randomly allocated. One group received RCSRD metal copings and the other group received CR metal copings. Both types of restorations were fabricated on solid abutments with 5.5 mm of diameter. The copings were cemented with resin cement. After the cementation procedure, cement excess was carefully removed in both groups. Inspections of coping-abutment vertical marginal discrepancy were measured using scanning electronic microscopy (SEM) under 800× magnification. The independent sample Student's t test was used to detect differences between groups (p < 0.05). RESULTS: The RCSRD implant-supported metal coping group (57.80 ± 2.34 µm) showed statistically better vertical marginal discrepancy than the CR implant-supported metal coping group (64.40 ± 2.23 µm) (p = 0.001). CONCLUSION: The RCSRD implant-supported metal copings offer less vertical marginal discrepancy than the CR copings group. This new technique would decrease the marginal discrepancy with less bacterial filtration and biomechanical problems. CLINICAL SIGNIFICANCE: Retrievable cement/screw-retained design is another alternative technique for dental implant rehabilitation that combines the advantages of CR and SR prostheses. The hybrid design offers less vertical marginal discrepancy for better control of bacterial filtration and biomechanical problems.

Efeitos da ciclagem mecânica, técnica de confecção e diferentes cerâmicas sobre a adaptação marginal e resistência à fratura de próteses implantossuportadas / Effects of mechanical cycling, manufacturing technique and ceramics types on the marginal fit and fracture resistance of implant-supported prostheses

O objetivo desse estudo in vitro foi avaliar por meio da metodologia de ciclagem mecânica a adaptação marginal (vertical/horizontal) e resistência à fratura, verificando a decorrência e possíveis complicações protéticas de próteses parafusadas implantossuportadas (hexágono externo) confeccionadas por diferentes técnicas e materiais cerâmicos. Foram confeccionados 50 corpos de prova, pela técnica convencional e Computer aided design and Computer aided manufacturing (CAD-CAM) divididos em cinco grupos (n=10 por grupo) sendo MC (Metalocerâmica); ZrL (Coping fresado em zircônia com link mais aplicação de cerâmica feldspática); Zr (Coping fresado em zircônia mais aplicação de cerâmica feldspática); MZrL (Monolítica de zircônia com link); MZr (Monolítica de zircônia), os quais foram submetidos à ciclagem mecânica em uma angulação de 30°, a 37°C e submetidos a 5 x 106 ciclos com aplicação de carga de 150N a uma frequência de 2,0Hz. No capítulo 1 foram avaliados à adaptação marginal vertical e horizontal (µm) antes e após ciclagem mecânica em Microscópio Óptico Tridimensional (3D) e no capítulo 2 os padrões de falhas das cerâmicas em Estereomicroscópio e Microscópio eletrônico de varredura (MEV) pós ciclagem mecânica. Os dados quantitativos foram analisados quanto a distribuição de normalidade e adotou-se o teste mais adequado considerando o nível de significância de 0,05. Os resultados obtidos para o capítulo 1 foram que em relação a desadaptação marginal vertical antes da ciclagem mecânica (tempo inicial-T0), houve diferença significativa com maiores valores de desadaptação para MC (93,93±22,84µm) e MZrL (66,12±11,87µm), p<0.05, quando comparados à Zr (49,92±3µm) e MZr (49,76±3,9µm), unindo os grupos com (ZrL+MZrL: 63,04±9,33µm) e sem link (Zr+MZr: 49,84±3,38µm) comparados ao grupo controle (MC) houve diferença significativa entre todos os grupos, p< 0.05, com menores valores de desadaptação para o grupo sem link. Em termos de desadaptação marginal horizontal antes da ciclagem mecânica (tempo inicial - To), houve diferença significativa com maiores valores de desadaptação para o grupo MC (-130,275±34,97µm), p<0.05, e menores valores de desadaptação para o grupo MZr (- 10,35±23,14µm), p<0.05, quando comparados aos demais grupos, além disso para o grupo sem link (Zr: -70,27±22,61µ vs MZr: -10,35±23,14µ), houve diferença significativa (p<0.05) com menores valores de desadaptação para MZr. Unindo os grupos com (-75,98±14,17µm) e sem link (-40,31±37,73µm), foi identificada diferença significativa entre todos os grupos quando comparados ao controle (MC: -130,27±34,97µm), (p< 0.001), com menores valores para o grupo sem link. Em relação à comparação antes e após ciclagem (Tf-T0), para análise da adaptação marginal vertical, o grupo MC (10,05±5,74µm) foi o que apresentou maiores valores de desadaptação, p<0.05, quando comparado aos demais grupos, já para análise da adaptação marginal horizontal, o grupo Zr (3±13,97µm) apresentou diferença estatística, p<0.05, na comparação com ZrL (-4,48±13,59µm) e MZrL (-2,825±11,81µm), unindo os grupos com (- 3,65±12,72µm) e sem link (0,35±10,99µm), houve menores valores de desadaptação para o grupo sem link, p<0.05. Para o capítulo 2, um total de 14 amostras falharam (lascamento/fratura de cerâmica). Os grupos MZrL e MZr apresentaram significativamente menor associação de falhas, com apenas uma falha (MZr) (p=0.035), assim como em relação ao tipo de substrato, os grupos MZrL e MZr apresentaram menos falhas (p=0,011). O uso de links e o número de ciclos não indicaram diferenças significativas entre os grupos (p≥0,05). Para área da falha, houve diferença significativa para o grupo Zr (15,55m²), p=0,029, apresentando maior extensão de área quando comparado aos demais. Em relação ao local da falha o grupo MC apresentou uma maior quantidade de falhas, com 5 falhas na região de orifício do parafuso quando comparado aos demais (p=0,043), os quais apresentaram falhas em diferentes locais. Portanto, o uso da tecnologia CAD/CAM foi o que resultou em menores valores de desadaptação marginal vertical e horizontal, assim como para resistência à fratura com destaque para as coroas monolíticas de zircônia(AU)

The aim of this in vitro study was to evaluate, through the mechanical cycling methodology, the marginal fit (vertical / horizontal) and fracture resistance, verifying the outcome and possible prosthetic complications of screwed-retained prostheses (external hexagon) made by different techniques and ceramic materials. Fifty specimens were made using the conventional technique and Computer aided design and Computer aided manufacturing (CAD-CAM) divided into five groups (n = 10 per group) being MC (Metal-ceramics crowns); ZrL (Coping milled in zirconia with link and covered feldspar ceramic); Zr (Coping milled in zirconia with covered feldspar ceramic); MZrL (Monolithic zirconia with link); MZr (Monolithic zirconia), which were subjected to mechanical cycling at an angle of 30 °, at 37 ° C and subjected to 5 x 106 cycles with a 150N load application at a frequency of 2.0Hz. In chapter 1, the vertical and horizontal marginal fit (µm) were evaluated before and after mechanical cycling under a threedimensional optical microscope (3D) and in chapter 2 the failure modes by the stereomicroscope and scanning electron microscope (SEM) after mechanical cycling. Quantitative data were analyzed for normality distribution and the most appropriate statistical test was adopted considering the significance level of 0.05. The results obtained for chapter 1 were that in relation to vertical marginal misfit before mechanical cycling (initial time-T0), there was a significant difference with higher misfit values for MC (93.93 ± 22.84µm) and MZrL (66, 12 ± 11.87µm), p <0.05, when compared to Zr (49.92 ± 3µm) and MZr (49.76 ± 3.9µm), joining the groups with (ZrL + MZrL: 63.04 ± 9.33µm) and without link (Zr + MZr: 49.84 ± 3.38µm) compared to the control group (MC) there was a significant difference between all groups, p<0.05, with lower misfit values for the group without link. In terms of horizontal marginal misfit before to mechanical cycling (initial time - To), there was a significant difference with higher misfit values for the MC group (-130.275 ± 34.97µm), p<0.05, and lower misfit values for the group MZr (-10.35 ± 23.14µm), p < 0.05, when compared to the other groups, in addition for the group without a link (Zr: -70.27 ± 22.61µm vs MZr: -10.35 ± 23, 14µm), there was a significant difference (p< 0.05) with lower misfit values for MZr. Joining the groups with (-75.98 ± 14.17µm) and without link (-40.31 ± 37.73µm), a significant difference was identified between all groups when compared to the control (MC: -130.27 ± 34, 97µm), (p<0.001), with lower values for the group without a link. Regarding the comparison before and after cycling (Tf-T0), for analysis of vertical marginal fit, the MC group (10.05 ± 5.74µm) was the one with the highest misfit values, p <0.05, when compared to the others groups, already for analysis of the horizontal marginal adaptation, the Zr group (3 ± 13.97µm) showed statistical difference, p <0.05. For chapter 2, a total of 14 samples failed, the groups MZrL and MZr showed significantly less association of failures, with only one failure (MZr), p = 0.035, as well as in relation to the type of substrate, the groups MZrL and MZr showed fewer failures (p = 0.011). The use of links and the number of cycles did not indicate significant differences between the groups (p≥0.05). For the chipping and/or fracture dimensions, there was a significant difference for the Zr group (p = 0.029) presenting a larger area of chipping when compared to the others. Regarding the location of the failure, the MC group showed a greater number of chipping in the screw orifice region when compared to the others (p = 0.043), which failed in different locations. Therefore, the use of the CAD / CAM system resulted in lower values of vertical and horizontal marginal maladjustment, as well as fracture resistance, with emphasis on monolithic crowns(AU)

[Three-dimensional finite element analysis of four-implants supported mandibular overdentures using two different attachments].

Objective: To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method. Methods: Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures. Results: Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa). Conclusions: In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.

Three-dimensional finite element analysis of four-implants supported mandibular overdentures using two different attachments / 中华口腔医学杂志

Objective@#To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method.@*Methods@#Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures.@*Results@#Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa).@*Conclusions@#In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.

Comportamento biomecânico de diferentes protocolos cirúrgicos/protéticos para maxila atrófica: análise fotoelástica e extensométrica extensométrica / Biomechanical behavior of diferente surgical protocols for atrofic maxillas: photoelastic and Strain Gauge analysis

Os pacientes com maxila atrófica ainda representam um problema complexo para os cirurgiões dentistas, tornando sua reabilitação um grande desafio, devido à baixa quantidade e qualidade óssea, e também de áreas anatômicas a serem preservadas como a fossa nasal e o seio maxilar que pode apresentar-se pneumatizados. O objetivo deste estudo foi avaliar a distribuição de tensões qualitativa e quantitativamente, por meio da análise fotoelástica (AF) e extensométrica (AE), de três diferentes protocolos alternativos ao procedimento de enxertia óssea para a reabilitação implantossuportada de maxila atrófica: implante convencional (S- standard - 3,75x11,5mm) associado a implante curto (C) (5x7mm), implante convencional (S) associado a implante inclinado em 30º e dois implantes convencionais instalados no eixo axial utilizando prótese com extensão em cantilever. A partir de um protótipo da maxila edêntula com atrofia na região posterior, confeccionada por meio de um modelo digital 3D, os corpos de prova foram divididos em 04 grupos de 01 espécime cada para AF e quatro grupos de 05 espécimes para a AE. Foram confeccionados 24 modelos, destes 4 foram de resina fotoelástica (PL-2) e 20 de poliuretano (F160). Foram utilizados implantes do tipo cone morse e confeccionadas próteses fixas implantossuportadas múltiplas (14-16) parafusadas. Os grupos foram divididos de acordo com protocolo de reabilitação proposto em: ISA - dois implantes (S) paralelos ao eixo axial, sendo um instalado na região do primeiro pré-molar (14) e outro na região do primeiro molar (16); ISAICA - dois implantes instalados paralelos ao eixo axial, sendo um implante (S) na região do primeiro pré-molar (14) e um implante curto (C) na região do primeiro molar (16); ISAISI - dois implantes (S), sendo um paralelo ao eixo axial instalado na região do primeiro pré-molar (14) e outro com inclinação distal de 30° na região do primeiro molar (16) e ISAPC - dois implantes (S) paralelos ao eixo axial instalados na região do primeiro pré-molar (14) e segundo pré-molar (15), com o pôntico (16) em cantiliever. Para AF, o conjunto modelo fotoelástico/implante/prótese foi posicionado em um polariscópio circular associado a uma máquina de ensaio universal (EMIC), sendo aplicada força axial de 100N. As tensões geradas foram registradas fotograficamente e analisadas qualitativamente. Para AE, 6 extensômetros foram posicionados ao redor dos dois implantes de cada grupo. Os sinais elétricos foram captados por um aparelho de aquisição de dados (ASD2002). Os dados quantitativos foram submetidos a ANOVA e ao teste Tukey (P<0.005). Pela AF, os protocolos de tratamento ISAICA e ISAPC apresentaram maior número de franjas de alta tensão em comparação os protocolos ISAISI e ISA. Pela AE, os protocolos ISAICA e ISAPC apresentaram maiores valores de tensão (microstrain), sendo diferentes do grupo controle ISA (P<.005). Já o protocolo ISAICA não apresentou diferença do grupo controle. Conclui-se que o protocolo de reabilitação de maxila atrófica com associação de implante axial e implante com inclinação distal de 30° apresentou o melhor comportamento biomecânico, sendo considerado a melhor alternativa ao procedimento de enxertia óssea para a reabilitação implantossuportada de maxila atrófica(AU)

Patients with atrophic maxillary still represent a challenge to rehabilitate for dentists in general due to limitations on bone quantity and quality and the anatomical setting of the sites to be preserved, such as nasal cavity and maxillary sinus, that could be pneumatized. The aim of this study was to assess qualitative and quantitative the stress distribution, through photoelastic analysis (PA) and strain gauge (SG), of three alternative techniques to bone augmentation procedures for implant placement: standard implant (S- standard - 3,75x11,5mm) associated to short implant (C) (5x7mm), standard implant (S) associated to 30 º tilted implant, two conventional implants placed in the long axis and a cantilever prosthesis. A maxillary prototype model, with posterior atrophic region, was manufactured from a digital 3D model and divided into four groups with 01 specimen for the PA and 05 specimen for the SG. A total of 24 models were manufactured, 4 from photoelastic resin (PL-2) and 20 from polyurethane (F160). Morse taper implants were used and multiple screwed implant supported prostheses were manufactured (14-16). The groups were divided according to the rehabilitation protocol: ISA ­ two parallel implants in the long axis (S), one in the pre-molar region (14) and in the molar region (16); ISAICA ­ two parallel implants in the long axis, one standard (S) in the pre-molar region (14) and one short (C) in the molar region (16); ISAISI ­ two standard implants, one parallel to the long axis (14) and one tilted at 30˚ (16) and ISAPC ­ two parallel implants in the long axis, in the first (14) and second (15) pre molar region, with a cantilever prostheses (16). For the PA, the assemble photoelastic model/implants/prostheses was positioned in a circular polariscope associated to a universal test machine (EMIC), and an axial load of 100N applied. The tension generated were photographed and analyzed qualitatively. For the SGA, 6 extensometers were attached around two implants of each group. The electoral signals were captured with a data acquisition machine (ASD2001). The data were submitted to ANOVA and Tukey test (P <0.005). By AF, the ISAICA and ISAPC treatment protocols presented higher number of high-voltage fringes compared to the ISAISI and ISA protocols. By the AE, the ISAICA and ISAPC protocols presented higher values of tension (microstrain), being different from the ISA control group (P <.005). The ISAICA protocol did not present any difference in the control group. It was concluded that the protocol of atrophic maxilla rehabilitation with an association of axial implant and implant with distal inclination of 30 ° presented the best biomechanical behavior, being considered the best alternative to the bone grafting procedure for the implant-supported rehabilitation of atrophic maxilla(AU)