<p>In recent years, measuring customer satisfaction has become one of the key concerns of market research studies. One of the basic features of leading companies is their success in fulfilling their customers’ demands. For that reason, companies attempt to find out what essential factors dominate their customers’ purchasing habits.</p> <p>Millennium Research Group (MRG) - a global authority on medical tech- nology market intelligence - uses a web-based survey tool to collect informa- tion about customers’ level of satisfaction. One of their surveys is designed to gather information about the practitioner’s level of satisfaction on different brands of dental implants. The Dental Implants dataset obtained from the survey tool has thirty-four attributes, and practitioners were asked to rank or specify their level of satisfaction by assigning a score to each attribute.</p> <p>The basic question asked by the company was whether the attributes were useful to make customer behavior predictions. The aim of this study is to assess the reliability and accuracy of these measures and to build a model for future predictions, then, determine the attributes that are most influential</p> <p>in the practitioners’ purchasing decisions. Classification and regression trees (CART) and Partial least squares regression (PLSR) are the two statistical approaches used in this study to build a prediction model for the Dental Implants dataset.</p> <p>The prediction models generated, using both of the techniques, have rel- atively small prediction powers; which may be perceived as an indication of deficiency in the dataset. However, getting a small prediction power is gener- ally expected in market research studies. The research then attempts to find ways to improve the power of these models to get more accurate results. The model generated by CART analysis tends to have better prediction power and is more suitable for future predictions. Although PLSR provides extremely small prediction power, it helps finding out the most important attributes that influence the practitioners’ purchasing decisions. Improvements in pre- diction are sought by restricting the cases in the data to subsets that show better alignment between predictors and customer purchasing behaviour.</p> / Master of Science (MSc)

AIM: To evaluate marginal bone loss around dental implants at the 2nd stage abutment surgery and retrospectively evaluate the association of pre-surgical variables. MATERIAL AND METHODS: Eighty-seven subjects (41 Males and 46 females) were enrolled in this cohort. The subjects' ages ranged from 23 to 80 years. Two endosseous implant brands were utilized: Nobel Biocare and Straumann Bone Level . Clinical measurements (mesial, distal, buccal, and lingual) were recorded from the coronal margin of the implant platform to the bone margin with a periodontal probe (Williams periodontal probe, Hu-Friedy) at the time of implant placement and at the 2nd stage abutment surgery. The pre-surgical variables (medication intake, implant site, bone graft volume, membrane type, and smoking) were evaluated using Chi-square test. RESULTS: The marginal bone loss (MBL) difference was calculated. The Mean clinical MBL: Mesial = 0.71 mm, Distal = 0.56mm, Buccal/Labial = 0.65 mm, and Lingual/Palatal = 0.56 mm. The test showed no statistically significant difference between test and control subjects in each of the variables, with the exception of thyroid medication. A statistically significant (P value = 0.011) association was found between levothyroxine and MBL at the mesial measurement. CONCLUSION: This limited cohort study suggests that medication-controlled hypothyroidism patients may experience an increased risk of marginal alveolar bone loss around dental implants at the 2nd stage abutment surgery. The final determination will be recalculated when the study population reaches the estimated requirement of 200 subjects.

Among the prosthetic and implant biomaterials in the oral cavity currently exciting tremendous interest, titanium and resin are the main components of implants and dentures respectively. From their introduction in the oral cavity, a highly complex heterogeneous biofilm coats these biomaterials. The present thesis analyzes the complex relationships that are formed between one single microorganism (Candida albicans), one defence system of the oral cavity (oral peroxidases) and the two aforementioned biomaterials (titanium and resin). These biomaterials are indeed in contact with peroxidases: myeloperoxidase from neutrophils and sialoperoxidase from salivary secretions. Oral peroxidases belong to the salivary non immune innate defence mechanisms that control the oral microbial flora. In the presence of hydrogen peroxide (H2O2), they catalyze in vivo the oxidation of thiocyanate (SCN-) into hypothiocyanite (OSCN-), in vitro the oxidation of iodide (I-) into hypoiodite (OI-). In the salivary compartment and in oral biofilms, H2O2 is mainly formed by bacteria. In our investigations, H2O2 was produced by an enzyme sequence glucose (G) / glucose-oxidase (GOD). The OSCN- and OI- are antibacterial, antiviral and antifungal oxidants. Few studies have considered their action on Candida biofilms.<p>Candida albicans is a commensal yeast of the oral cavity which can turn parasitic when the host immune defences are weakened. This fungus forms biofilms on biomaterials within the mouth, especially on dentures, the decontamination of these prostheses is therefore essential to avoid the risk of candidosis. (Candida et prothèses dentaires. Ahariz M. Loeb I. Courtois Ph. Rev. Stomatol. Chir. Maxillofac. 111: 74-78, 2010).<p>In vitro, our investigations aimed to analyze the relationships between peroxidase systems and Candida. The effect of peroxidase systems (G / GOD / KI or KSCN / peroxidase) on Candida suspensions, on biofilms already formed or in formation was evaluated with various inputs of hydrogen peroxide and was studied by incorporation of enzymatic sequences in the culture media used for Candida biofilms formation. The susceptibility of Candida albicans ATCC 10231 to OSCN- versus to OI-, produced by lactoperoxidase (LPO), was studied in three different experimental models: - in a liquid culture medium – on a solid medium (with agarose gel), - in a biofilm model developed in the context of this work. The latter consisted of titanium powder suspended in Sabouraud broth contaminated with Candida albicans. The growth of Candida in the supernatant (planktonic phase) was evaluated by turbidimetry and the biomass of yeasts adherent to biomaterials (attached phase) by the tetrazolium salt MTT method. Enzymatic studies have allowed the optimization of the concentrations and activities of peroxidase systems components and the illustration of the competition between thiocyanate and iodide for lactoperoxidase. Peroxidase systems G/GOD/I-/LPO and G/GOD/SCN-/LPO prevented or limited the growth of Candida in the planktonic and attached phases on titanium powder for at least 21 days. At a dose of GOD (0.2 U / ml), the system G/GOD/I-/LPO has limited the development of planktonic and attached phases for 4 days while the system G/ GOD/SCN-/LPO has shown an inhibitory effect only in the first 2 days of incubation. (Candida albicans susceptibility to lactoperoxidase-generated hypoiodite. Ahariz M. Courtois Ph. Clinical, cosmetic and investigational dentistry; 2: 69-78, 2010).<p>In other experiments, peroxidase was adsorbed on titanium sheets in order to modify their surface and give them the property of inhibiting biofilm formation of Candida after addition of the enzyme substrates. Enzymatic studies and X-ray photoelectron spectroscopy (XPS) showed the adsorption of lactoperoxidase to titanium. In vivo, peroxidases are adsorbed on titanium healing abutments. (Adsorption of peroxidase on titanium surfaces: A pilot study. Ahariz M. Mouhyi J. Louette P. Van Reck J. Malevez C. Courtois P. J. Biomed. Mater. Res. 52: 567-571, 2000).<p>The development of the Candida biofilm was followed on titanium (powder or sheets) as well as on resin. Planktonic and attached phases have been monitored for 21 days. The presence of an exopolysaccharide matrix secreted by the yeasts has been observed with light microscopy and confirmed with fluorescence using the calcofluor method. In a series of experiments on titanium and resin sheets, an attached phase was demonstrated by the same techniques. The efficiency of the peroxidase system using iodide as a substrate was demonstrated when the enzyme was in solution and when it was preadsorbed on titanium (Candida albicans biofilm on titanium: effect of peroxidase precoating. Ahariz M. Courtois Ph. Medical Devices: Evidence and Research; 3: 33-40, 2010).<p>The incorporation in oral gels of other molecules present in exocrine secretions is a research direction that was also discussed: the present studies have demonstrated the in vitro benefits of peroxidase systems (with thiocyanate, chloride or especially iodide as substrates) acting in synergy with colostrum, lactoferrin and lysozyme. But the formulation of specialities that contain these natural antimicrobials is difficult to transpose in vivo as the complexity of the oral environment is very large (Denture contamination by yeasts in the elderly. Vanden Abbeele A. de Meel H. Ahariz M. Perraudin J.-P. Beyer I. Courtois P. Gerodontology; 25: 222-228, 2008).<p>Investigations pursued in vivo in 155 patients allowed the determination of the wild strains of Candida sp present on the fitting surface of the removable dental appliance and on the corresponding palatal mucosa. The link between the presence of yeasts and a reduced salivary flow was confirmed. These wild strains were directly grown and identified on Petri dishes (ChromAgar™ medium) from the macroscopic morphology of colonies and from additional tests (germination test in human serum, formation of chlamydoconidies on RAT medium, API™ galleries identification system ). For a period of two weeks, 14 patients accepted the daily application of a gel on the fitting surface of their denture. It was a double-blind comparison of an active gel containing the thiocyanate - lysozyme - lactoferrin - colostrum complete system with a control gel inactivated by heating. Data analysis showed a reduction in the number of colonies on the palatal mucosa by Candida sp, but not on the denture itself. By contrast, decontamination ex vivo of dentures by immersion in a bath (at room temperature or 37° C) containing either G/GOD producing H2O2 or the complete peroxidase system G/GOD/KI/L producing OI- demonstrated the efficiency of hypoiodite.<p><p><p>Parmi les biomatériaux prothétiques et implantaires qui connaissent actuellement un essor considérable dans la sphère orale, le titane est le composant principal des implants et la résine celui des prothèses dentaires. Dès leur introduction dans la cavité orale, un biofilm hétérogène très complexe les recouvre. Cette thèse analyse la complexité des relations qui se nouent entre un seul micro-organisme (Candida albicans), un système de défense de la cavité orale (les peroxydases orales) et les 2 biomatériaux précités (titane, résine). Ces biomatériaux sont en effet, dans le milieu oral, au contact de peroxydases: la myéloperoxydase des neutrophiles et la sialoperoxydase des sécrétions salivaires. Les peroxydases orales appartiennent aux mécanismes salivaires de défense innée non immunitaires qui contrôlent la flore microbienne orale. En présence de peroxyde d’hydrogène (H2O2), elles catalysent in vivo l’oxydation du thiocyanate (SCN-) en hypothiocyanite (OSCN-) et in vitro l’oxydation d’iodure (I-) en hypoiodite (OI-). Dans le compartiment salivaire et dans les biofilms oraux, l’H2O2 provient essentiellement des bactéries. Dans nos investigations, l’H2O2 était produit par une séquence enzymatique glucose (G) / glucose-oxydase (GOD). L’OSCN- et l’OI- sont des oxydants antibactériens, antiviraux et antifongiques. Peu d’études envisagent leur action sur les biofilms à Candida.<p>\ / Doctorat en Sciences dentaires / info:eu-repo/semantics/nonPublished

Devido à crescente utilização de componentes cerâmicos como estruturas de suporte para restaurações sobre implantes e a ausência de resultados conclusivos, em longo prazo, sobre a influência deste tipo de material no processo de formação e manutenção do biofilme oral e saúde dos tecidos peri-implantares, este estudo teve por objetivo investigar o perfil microbiano do biofilme formado sobre próteses unitárias de implantes com conectores de zircônia (Zr) ou titânio (Ti) e sua implicação clínica nos tecidos de suporte ao longo de 3 anos de função. Vinte indivíduos saudáveis participaram do estudo e foram reabilitados com implantes dentários e coroas protéticas unitárias cimentadas sobre conectores de zircônia (n=10; região anterior de maxila) ou conectores de titânio (n=10; região posterior da mandíbula). Amostras de biofilmes supra e subgengival, e dados de indicadores clínicos (profundidade e sangramento à sondagem, recessão gengival e nível ósseo marginal) foram coletados dos sítios peri-implantares e dentes contralaterais em 4 períodos distintos, na instalação da prótese (T0) e após 12 (T1), 24 (T2) e 36 (T3) meses de função mastigatória. Trinta e sete espécies microbianas foram identificadas e quantificadas pelo método de hibridização DNA-DNA Checkerboard. Os dados foram submetidos à análise estatística não-paramétrica de regressão linear mista (Brunner and Langer nonparametric analysis of longitudinal data in factorial experiments) e múltiplas comparações foram realizadas por meio do teste de Friedman-Conover, corrigido por Benjamini-Hockberg False Discovery Rate (FDR). Para análise da reabsorção óssea marginal foi utilizado o teste Two-Way ANOVA. Todas as análises foram realizadas com um nível de significância de 5%. O perfil microbiano detectado nos implantes restaurados com conectores de zircônia, titânio e seus respectivos dentes contralaterais foi semelhante a partir do período de 12 meses de investigação. Espécies patogênicas e não-patogênicas foram detectadas nos biofilmes supra e subgengival dos dois substratos, com um aumento significante da quantificação das espécies ao longo do tempo. Apesar do perfil semelhante, os substratos investigados influenciaram na quantidade total de micro-organismos identificados (p<0,05). Os conectores de Zr apresentaram maior quantificação de genomas totais nas amostras subgengivais quando comparadas aos conectores de Ti (p<0,05). A profundidade de sondagem reduziu nos implantes com Zr após 12 meses, enquanto nos implantes com Ti aumentou no mesmo período (p<0,05). O sangramento à sondagem e a recessão gengival aumentaram ao longo do tempo para Zr e Ti. Não houve diferença significante nos valores da reabsorção óssea marginal, entre os dois materiais, após 36 meses (p>0,05). De modo geral, pode-se concluir que o perfil microbiano dos biofilmes supra e subgengival dos implantes com Zr ou Ti foi semelhante, com um aumento da quantificação das espécies ao longo do tempo. A microbiota investigada neste estudo parece não ter influenciado os indicadores clínicos ao longo dos 36 meses de acompanhamento. Os resultados clínicos sugerem a manutenção da saúde dos tecidos peri-implantares nos diferentes substratos investigados / Due to the increasing use of ceramic abutments as support structures for implant restorations and the lack of long-term conclusive results on the influence of this type of material on the oral biofilm formation and maintenance of peri-implant tissue health, the purpose of this study was to investigate the microbial biofilm profiles of single-implant restorations using zirconia (Zr) or titanium (Ti) abutments and their clinical implications in the supporting tissues over a 3-year period. Twenty healthy subjects participated in the study and were rehabilitated with single-unit implant restorations cemented on zirconia (n = 10; anterior maxilla) or titanium abutments (n = 10; posterior mandible). Supra and subgingival biofilm samples, and clinical parameters data (probing depth and bleeding on probing, gingival recession and marginal bone level) were collected from the peri-implant sites and contralateral teeth at 4 different time-periods, at the prosthesis installation (T0) and after 12 (T1), 24 (T2) and 36 (T3) months of loading. Thirty-seven microbial species were identified and quantified by DNA-DNA Checkerboard hybridization method. The data were submitted to Brunner and Langer nonparametric analysis of longitudinal data in factorial experiments followed by Friedman-Conover multiple comparisons test, corrected by Benjamin-Hockberg False Discovery Rate (FDR). Two-Way repeated ANOVA was used to analyze marginal bone resorption. Statistical significance was set at 0.05 probability level. The microbial profiles detected in the implants restored with zirconia or titanium abutments and their respective contralateral teeth were similar from the 12-month follow-up. Pathogenic and non-pathogenic species were detected in the supra and subgingival biofilms of the two substrates, with a significant increase in the microbial counts over time. Despite the similar profile, the investigated substrates influenced the total amount of microorganisms identified (p <0.05). The Zr abutments presented higher total genome counts in the subgingival samples when compared to Ti abutments (p <0.05). The probing depth reduced in the implants with Zr after 12 months, whereas in the implants with Ti increased in the same period (p <0.05). Bleeding on probing and gingival recession increased over time for both Zr and Ti. There was no significant difference in marginal bone resorption values between the two materials after 36 months (p>0.05). Overall, it can be concluded that the microbial profile of supra and subgingival biofilms of the implants with Zr or Ti was quite similar, and the microbial counts increased over time. The microbiota investigated in this study does not seem to have influenced the clinical parameters during the 36 months of follow-up. The clinical results suggest the maintenance of peri-implant tissue health in the different substrates investigated

Objetivo. Esta revisão sistemática com metanálise investigou se o protocolo de carga imediata tem mais desvantagens clínicas do que o protocolo de carga precoce para implantes dentários individuais em termos de perda óssea marginal e taxa de sobrevivência de coroas de implantes unitários. Material e métodos: Dois revisores realizaram uma pesquisa avançada de banco de dados eletrônico, sem restrição de idioma ou data, no Medline / PubMed, Embase e na Biblioteca Cochrane até maio de 2016. Os estudos foram escolhidos por título e resumo para triagem, de acordo com os seguintes critérios de inclusão: estudos de implantes dentários; estudos de coorte (prospectivos e retrospectivos) e estudos clínicos aleatorizados; amostras envolvendo pacientes parcialmente desdentados; implantes com carga imediata; carregamento precoce de implantes; e n>=10. Após a leitura do texto completo os artigos foram excluídos de acordo com os seguintes critérios: 1) estudos sem implantes dentários de titânio; 2) revisão sistemática, descrição de técnica, intervenções, protocolos, estudos in vitro e relato de casos; 3) estudos sem implantes com carga imediata; 4) estudos sem implantes com carga precoce; 5) amostras menores do que 10 pacientes; 6) implantes unidos; 7) grupos isolados (pacientes com diabetes, cardiopatas, pacientes com bruxismo ou osso irradiado); 8) acompanhamento menor do que 6 meses; 9) estudos sem taxa de sobrevida; 10) estudos sem acompanhamento da perda óssea marginal; 11) taxa de desistência maior do que 30%. Resultados. Dos 5710 estudos inicialmente identificados, 5 preencheram os critérios de inclusão. Uma metanálise que gerou diferença de risco (DR) e diferença média (DM) com um intervalo de confiança de 95% (IC 95%) foi realizada. Os estudos incluídos não mostraram diferenças significativas entre os protocolos de carga precoce e imediata em coroas de implante unitário em relação à taxa de sobrevivência em 1 e 3 anos (RD -0,00, IC 95% -0,04 a 0,04; P = 0,990 por 1 ano e P = 0,980 por 3 anos), ou perda óssea marginal em 1 (DM 0,09, 95% IC -0,02 a 0,19; P = 0,110) e 3 anos (DM -0,23, 95% IC -0,47 a 0,01; P =, 060 ). Conclusões: Esta revisão sistemática não mostrou diferenças significativas entre os protocolos de carga inicial e imediata em coroas de implante unitário em relação à taxa de sobrevivência ou perda óssea marginal em 1 ou 3 anos. / Purpose. This systematic review and meta-analysis investigated whether the immediate loading protocol has more clinical disadvantages than the early loading protocol for single dental implants in terms of the marginal bone loss and survival rate of single implant crowns. Material and methods. Two reviewers conducted an advanced electronic database search, with no language or date restriction, in Medline/PubMed, Embase, and the Cochrane Library up to May 2016. Studies were chosen by title and abstract for screening in accordance with the following inclusion criteria: dental implants studies; cohort studies (prospective and retrospective) and randomized controlled trials; samples involving partially edentulous patients; immediate loading implants; early loading implants; and n>=10. Results. Of the 5710 studies initially identified, 5 fulfilled the inclusion criteria. A meta-analysis yielding risk difference (RD) and mean difference (MD) with a confidence interval of 95% (95% CI) was performed. The included trials showed no significant differences between early and immediate loading protocols in single implant crowns with regard to survival rate at 1 and 3 years (RD -0.00, 95% CI -0.04 to 0.04; P=.990 for 1 year and P=.980 for 3 years), or marginal bone loss at 1 (MD 0.09, 95% CI -0.02 to 0.19; P=.110) and 3 years (MD -0.23, 95% CI -0.47 to 0.01; P=.060). Conclusions. This systematic review showed no significant differences between early and immediate loading protocols in single implant crowns with regard to survival rate or marginal bone loss at 1 or 3 years.

No description available.

A qualidade óssea, bem como a estabilidade inicial dos implantes, está diretamente relacionada com o sucesso das reabilitações na implantodontia. O presente estudo teve como objetivo analisar a correlação entre índices radiomorfométricos de densidade óssea por meio de radiografias panorâmicas, perfil de qualidade óssea com o auxílio de Tomografia Computadorizada de Feixe Cônico (TCFC) com o uso do software de imagens OsiriX, Análise da Frequência de Ressonância (RFA) e Torque de Inserção do implante. Foram avaliados 160 implantes de 72 indivíduos, com média etária de 55,5 (±10,5) anos. Nas radiografias panorâmicas foram obtidos os índices IM, IPM e ICM, e nas tomografias computadorizadas de feixe cônico, os valores de pixels e a espessura da cortical da crista óssea alveolar, além da estabilidade primária por meio do torque de inserção e análise da frequência de ressonância. Os resultados foram analisados pelo coeficiente de correlação de Spearman, para p<= 0,01 foi obtido entre o torque de inserção e valores de pixels (0.330), o torque de inserção e a espessura da cortical da crista alveolar (0.339), o torque de inserção e o ISQ vestibulo-lingual (0.193), os valores de pixels e espessura da cortical da crista alveolar (0.377), as duas direções vestíbulo-lingual e mesio-distal do ISQ (0.674), o ISQ vestíbulo-lingual e a espessura da cortical da crista alveolar (0.270); os índices radiomorfométricos foram correlacionados entre eles e para p<= 0,05 foi obtido entre torque de inserção e ISQ mesio-distal (0.131), entre o ISQ vestibulo-lingual e os valores de pixels (0.156) e ISQ mesio-distal e IPMI esquerdo (0.149) e ISQ mesio-distal e IPMS esquerdo (0.145). Existe correlação entre a TCFC, o torque de inserção e a RFA na avaliação da qualidade óssea. É possível utilizar, pré-cirurgicamente, os exames de TCFC para avaliar a qualidade e quantidade óssea, tendo em vista as correlações obtidas neste estudo. / The bone quality and initial stability of implants are directly related to the success of rehabilitation in implantology. The aim of this study was to analyze the correlation between radiomorphometric indexes of bone density through panoramic radiographic images, bone quality profile using the Cone-Beam Computed Tomography (CBCT) and the OsiriX imaging software, Resonance Frequency Analysis (RFA) and insertion torque implant. One hundred and sixty implants were evaluated in 72 individuals with a mean age of 55.5 (± 10.5) years. In the panoramic radiographic images, the IM, IPM and ICM indexes were assessed. For the cone beam computed tomography, the analyses included pixel values, thickness of cortical bone crest, as well as the primary stability through the insertion torque and resonance frequency. The results were analyzed by Spearman correlation coefficient for p <= 0.01. The values between insertion torque and pixel were (0.330), the insertion torque and cortical thickness of the alveolar crest were (0.339), for torque insertion and ISQ vestibule-lingual (0.193), and for pixel values and cortical thickness of the alveolar crest (0.377). Considering both directions bucco-lingual and mesial-distal ISQ the values were (0.674), the bucco-lingual ISQ and cortical thickness of the alveolar ridge were (0.270); the radiomorphometric indexes were correlated between themselves. Values of p <= 0.05 were obtained between insertion torque and mesio-distal ISQ (0.131), as well as the ISQ vestibule-lingual and the pixel values (0.156) and also mesial-distal ISQ and left IPMI (0.149) and mesial-distal ISQ and left IPMS (0.145). There is a correlation between the CBCT, the insertion torque and RFA in the evaluation of bone quality. CBCT scans can be used prior to surgery, in order to assess bone quality and quantity, considering the correlations obtained in this study.

O aumento ósseo de rebordos mandibulares posteriores atróficos continua sendo um grande desafio para os cirurgiões orais. Sabe-se que o osso alógeno pode ser utilizado para realização de enxertos aposicionais nessa região, com bons resultados clínicos e histomorfométricos, porém não há estudos sobre a manutenção óssea volumétrica desses enxertos em longo prazo. O objetivo deste estudo foi avaliar tomograficamente, por meio de medidas lineares e volumétricas, a dinâmica de manutenção do osso alógeno córtico-medular fresco congelado em bloco na cirurgia de aumento ósseo de rebordos mandibulares posteriores atróficos em humanos. Os pacientes do estudo foram submetidos à realização de enxertos aposicionais de osso alógeno fresco congelado em bloco na região posterior mandíbula. Os blocos foram modelados manualmente, fixados aos leitos receptores com parafusos de titânio de 1,5 x 10,0 mm e recobertos com osso mineral bovino e membrana absorvível de colágeno suíno. Para avaliação do ganho ósseo em altura, espessura e volume, cada paciente foi submetido a exames de tomografia computadorizada de feixe cônico (TCFC) em 03 períodos experimentais: imediatamente após a cirurgia de enxerto (T1); 06 meses após a enxertia, no momento de instalação dos implantes (T2) e 01 ano após a carga funcional protética (T3). Os dados obtidos foram tabulados e submetidos à análise estatística por meio do teste de Kruskal-Wallis seguido do post test de Tukey. Para comparação entre dois grupos, foram empregados os testes t de Student e Mann-Whitney. Foram operados 20 pacientes, 15 mulheres e 05 homens, com idade entre 37 e 64 anos (51,8 ± 7,5 anos), para os quais um total de 50 blocos ósseos foi utilizado. Dos 50 blocos, 8% foram utilizados para aumento ósseo em altura, 50% para espessura e 42% para altura e espessura. O ganho ósseo em altura foi de T1 = 5,15 ± 1,04 mm, T2 = 3,91± 0,94 mm e T3 = 2,92 ± 0,71 mm; em espessura, foi de T1 = 6,42 ± 1,20 mm, T2 = 4,64 ± 1,32 mm e T3 = 4,02 ± 0,71 mm. O ganho ósseo em volume foi de T1 = 1176,62 ± 358,08 mm³, T2 = 785,78 ± 201,16 mm³ e T3 = 689,72 ± 187,45 mm³. Foi observada diferença estátistica entre os três tempos experimentais tanto para altura quanto para espessura. Porém, volumetricamente, não foi possível observar diferença entre T2 e T3. No total, foram instalados 50 implantes (01 implante/bloco), para os quais foi obtida uma taxa de sobrevivência de 96% após 31,75 ± 6,99 meses de acompanhamento pós-operatório. Com base nos resultados obtidos, pode-se concluir que o osso alógeno fresco congelado em bloco constitui uma alternativa viável para cirurgia de aumento de rebordo mandibulares posteriores atróficos, apresentando uma manutenção volumétrica aceitável em longo prazo e permitindo a instalação de implantes com alta taxa de sucesso. / Atrophic posterior mandible bone augmentation remains a major challenge for oral surgeons. It is known that allogenic bone can be used for appositional grafts in this region, with good clinical and histomorphometric results, howerer there are no long term studies on the volumetric bone maintenance of these grafts. The objective of this study was to evaluate tomographically, through linear and volumetric measurements, the dynamic maintenance of corticocancellous fresh frozen allograft bone blocks for atrophic posterior mandible augmentation in humans. The patients of the study were submitted to fresh frozen allograft bone block appositional grafting surgery in the posterior mandible. The blocks were manually shaped, fixed to the recipient bed with 1.5 x 10.0 mm titanium screws and covered with bovine bone mineral and porcine collagen absorbable membrane. For assessment of bone gain in height, thickness and volume, each patient underwent cone beam computed tomography (CBCT) at 03 experimental periods: immediately after grafting surgery (T1); 06 months after grafting, at the implant placement (T2) and 01 year after prosthetic functional loading (T3). Data were tabulated and submitted to statistical analysis using the Kruskal-Wallis test followed by Tukey post test. For comparison between two groups, Student t test and Mann-Whitney were employed. Twenty patients were operated, 15 women and 05 men, aged between 37 and 64 years (5.8 ± 7.5 years), for which a total of 50 bone blocks was used. Of the 50 blocks, 8% were used for bone augmentation in height, 50% in thickness and 42% for both height and thickness. The bone gain in height was 5.15 ± 1.04 T1 = mm, T2 = 3.91 ± 0.94 mm and T3 = 2.92 ± 0.71 mm; while in thickness was T1 = 6.42 mm ± 1.20, 4.64 ± T2 = T3 = 1.32 mm and 4.02 ± 0.71 mm. The bone gain in volume was T1 = 1176.62 ± 358.08 mm³, T2 = 785.78 ± 201.16 mm³ and T3 = 689.72 ± 187.45 mm³. Statistical difference was observed between the three experimental times for both height and thickness. However, volumetrically, no difference was observed between T2 and T3. Fifty implants were installed (01 implant/block), with a survival rate of 96% after 31.75 ± 6.99 months of postoperative follow-up. Based on these results, it can be concluded that the fresh-frozen allograft bone block is a viable alternative for atrophic posterior mandible augmentation, presenting an acceptable long-term volumetric bone maintenance and allowing dental implant installation with high success rates.

Nos casos de perda óssea vertical severa, principalmente em áreas posteriores da mandíbula, o uso de implantes curtos associado a próteses fixas metaloplásticas esplintadas pode ser uma alternativa às cirurgias de enxerto ósseo e a melhor transmissão de tensões ao osso adjacente, respectivamente. Dentre os métodos que avaliam a distribuição de tensões em torno dos implantes, a Correlação de Imagem Digital (CID) leva vantagens no que diz respeito à possibilidade de avaliar a distribuição das tensões de forma contínua por meio de imagens obtidas ao longo do tempo, durante carregamento oclusal. Diante disso, este trabalho avaliou qualitativa e quantitativamente o desempenho biomecânico de próteses fixas metaloplásticas parafusadas, unidas e isoladas, sobre implantes de diferentes comprimentos, posicionados na região posterior da mandíbula, por meio do método de CID. A partir de quatro modelos mestres, foram confeccionados quatro modelos em resina de poliuretano F16, simulando extremidade livre mandibular, com o dente 44 em resina (Luxatemp) e os dentes 45, 46 e 47 substituídos por implantes curtos (4 x 5 mm) e/ou convencionais (4 x 11 mm). Os grupos (G) deste estudo foram: G1 (dois implantes convencionais [45 e 46] e um curto [47]), G2 (um implante convencional [45] e dois curtos [46 e 47]), G3 (três implantes curtos) e G4 (três implantes convencionais). Próteses fixas metaloplásticas unidas e isoladas foram parafusadas sobre os intermediários e submetidas a diferentes carregamentos oclusais de 250N: puntiforme (distal do 47 e mesial do 45) e oclusal distribuído. Tensões na direção horizontal (&epsilon;xx) foram calculadas e comparadas qualitativa e quantitativamente pelo software de CID (Davis 8.0, LaVision GmbH). Em geral, houve uma concentração de tensões em maior intensidade nas áreas onde os implantes curtos estavam posicionados. No carregamento puntiforme no segundo molar, houve uma predominância de tensões de compressão e tração nos planejamentos com coroas unidas e isoladas, respectivamente, e as tensões de maior magnitude foram encontradas no G2, G3 e G4 com coroas isoladas (p>0,05), apresentando valores mediados (&mu;S) equivalentes a 396,08, 360,45 e 354,04, respectivamente. No carregamento puntiforme envolvendo o segundo pré-molar, houve predominância de tensões de compressão em todos os planejamentos, com magnitudes mais elevadas nos grupos com coroas unidas (p<0,05). As simulações com carga oclusal distribuída revelaram, também, predominância de tensões de compressão em todos os planejamentos, com maior magnitude nos grupos com coroas unidas, sobretudo no G1 (-464,05±106,43) e G3 (-474,39±179,54) e com diferenças estatisticamente significantes em relação aos demais grupos (p<0,05). Dentro das limitações deste estudo, pode-se concluir que a esplintagem das coroas sobre múltiplos implantes promoveu maior concentração de tensões em torno dos implantes durante os carregamentos puntiforme no segundo pré-molar e oclusal distribuído, reforçando a necessidade de contato interproximal e ajuste oclusal efetivos para promover melhor distribuição das tensões. Adicionalmente, a combinação de implantes curtos e convencionais parece ser uma alternativa viável na reabilitação de áreas edêntulas posteriores com altura óssea reduzida. / In cases of severe vertical bone loss, especially in the posterior region of the mandible, the use of short implants associated with splinted resin-veneered fixed dental prostheses (FDPs) can be an alternative to bone graft surgery and better force transmission to the adjacent bone, respectively. Among the methods to evaluate the stress distribution around the implants, the digital image correlation (DIC) has advantages as regards the possibility of evaluating the stress distribution continuously using images taken over time, during occlusal loading. Thus, this study evaluated qualitatively and quantitatively the biomechanical behavior of splinted and non-splinted resin-veneered FDPs, screw-retained on implants of different lengths positioned in the posterior region of the mandible with the aid of the DIC method. Four F16 polyurethane resin models were fabricated to simulate half of the mandibular arch containing tooth 44 in resin (Luxatemp) and teeth 45, 46 and 47 replaced by short (4 x 5 mm) and/or conventional (4 x 11 mm) implants. Groups (G) of this study were: G1 (two conventional implants [45 and 46] and one short implant [47]), G2 (one conventional implant [45] and two short implants [46 and 47]) G3 (three short implants) and G4 (three conventional implants). Splinted and non-splinted FDPs were screwed to the implant abutment and subjected to different oclusal loads of 250N: punctiform (45 mesial and 47 distal) and balanced occlusal load. Strains in the horizontal direction (&epsilon;xx) were calculated based on displacement and compared qualitatively and quantitatively by the DIC software (Davis 8.0, LaVision Inc.). In general, there was a stress concentration at higher intensity in those areas where short implants were placed. In punctiform load on the second molar, there was a compressive and tensile stresses predominance when splinted and non-splinted crowns were used, respectively, and the stresses of greater magnitude were found in the G2, G3 and G4 with non-splinted crowns (p>0.05), showing median values (&mu;S) equivalent to 396.08, 360.45 and 354.04, respectively. In punctiform load involving the second premolar, there was a compressive stress predominance in all planning with highest magnitudes in groups with splinted crowns (p<0.05). The oclusal load distributed simulations also revealed compressive stresses predominance in all planning, with greater magnitude in groups with splinted crowns, especially in G1 (-464.05 ± 106.43) and G3 (-474.39 ± 179.54), both with statistically significant differences when compared to the other groups (p<0.05). Within the limitations of this study, it can be concluded that splinting multiple adjacent implant supported provided a high stress concentration around the implants during punctiform (45 mesial) and balanced occlusal load, reinforcing the need for effective interproximal contact and oclusal adjustment to promote better stress distribution. Additionally, the combination of short and conventional implants seems to be a viable alternative in the rehabilitation of mandibular free end with reduced bone height.

O objetivo desse estudo foi avaliar as taxas de sobrevida de implantes unitários, instalados na maxila, com diferentes tratamentos de superfícies: oxidação anódica (AO), duplo ataque ácido (DAE), ataque ácido e jateamento (SAE) e ataque ácido e jateamento modificada (SAE modificada). Também avaliou a influência de outras variáveis sobre estas taxas. Foram avaliados pacientes com implantes unitários em maxila, atendidos no Centro Odontológico da Polícia Militar de São Paulo e do Centro de Excelência em Prótese e Implantes da Universidade de São Paulo (Brasil), entre janeiro de 2008 e julho de 2013. Os seguintes dados foram coletados: sexo do paciente, características do implante (forma, diâmetro, comprimento), tratamento de superfície, localização do implante (maxila anterior ou posterior), presença de enxerto ósseo e falhas de implantes. O desfecho primário foi a perda do implante (falha). Estatísticas descritivas foram realizadas para caracterizar a distribuição de frequência de implantes em relação às variáveis. A análise da falha do implante foi feita por curvas de sobrevida de Kaplan-Meier. O teste de Mantel-Cox identificou as variáveis associadas à falha do implante ao longo do tempo. A amostra analisada foi constituída por 1076 implantes em 549 pacientes. As falhas ocorreram em 20 implantes (1,9%), 15 deles (75%) em homens e 5 em mulheres (25%). A frequência de falha foi maior em regiões de enxerto ósseo, e esta diferença ocorreu nos implantes em homens e com superfície DAE. A presença de enxerto aumentou em seis vezes as chances de falha do implante em relação às áreas de osso natural. Nos pacientes com implantes com superfície DAE estimou-se que essa chance de falha do implante em área de enxerto aumentou em nove vezes. / The purpose was evaluate the survival rates of single implants installed in maxilla with different surface treatments: anodic oxidation (AO), dual acid-etching (DAE), sandblasted and acid-etched (SAE) e sandblasted and acid-etched modified (SAE modified). It also evaluated the influence of other variables on these rates. Patients with installed single implants in the maxilla treated at Dental Center of Military Police of São Paulo and the Center for Excellence in Prosthodontics and Implants of the University of São Paulo (Brazil) between January 2008 and July 2013 were evaluated. The following data were collected: patient gender, implant characteristics (shape, diameter, length), surface treatment, location of the implant (anterior or posterior maxilla), presence of bone graft and implant failures. The primary outcome was the loss of the implant (failure). Descriptive statistics were used to characterize the frequency distribution of implants in relation to the variables. The analysis of implant failure was made by survival curves of Kaplan-Meier. The Mantel-Cox test was performed to identify variables associated with implant failure over time. The sample consisted of 1076 implants in 549 patients. Failures occurred in 20 implants (1.9%), while 15 of them (75%) were men and 5 women (25%). The frequency of failure was higher in regions of bone graft, and this difference was related to implants in men and in DAE implants. The presence of graft area increased by 6 times the chances of implant failure in relation to areas of natural bone. In DAE implants was estimated that the chance of failure of the implant graft area increased by 9 times.