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

Prosthetic complications and quality of life among wearers of mandibular overdenture with the Facility-Equator system

Abstract This longitudinal study aimed to assess the performance of the Facility-Equator system as mandibular overdenture (MO) retainers from a prosthetic perspective during 2 years of loading and to investigate the oral health-related quality of life (OHRQoL) and whether prosthetic events can affect the OHRQoL. Twenty-four patients (68.1 ± 7.51 years) reported their OHRQoL through the Geriatric Oral Health Assessment Index (GOHAI) and Oral Health Impact Profile (OHIP-EDENT) questionnaires before MO loading and after 1 and 2 years of usage. Prosthetic occurrences were recorded during this period. Data were analyzed using the Wilcoxon test, Mann-Whitney test, and Spearman correlation coefficients. Of the 127 prosthetic events that occurred in the first year, the most frequent events were prosthesis adjustments (16.5%), dislodgement of the Equator attachment (14.17%), and O-ring replacement (11.8%). Eighty-seven prosthetic events were recorded in the second year, the most frequent events being prosthesis adjustments (27.6%), O-ring replacement (20.7%), and recapturing the female matrix (11.5%). All domains of the GOHAI and OHIP-EDENT questionnaires exhibited a significant difference (p < 0.05) between the baseline and 1- and 2-year evaluations, except in the Social Disability and Psychological Discomfort domains (p > 0.05) of OHIP-EDENT after 1 year. Complications related to prosthetic maintenance, such as fracturing of the prosthesis, Equator dislodgement, prosthesis rebasing, and new overdenture confection, affect the OHRQoL (p < 0.05), primarily the Physical Pain and Discomfort domains, especially in the first year of MO loading.

Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study

Abstract Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

3D finite element model based on CT images of tooth: a simplified method of modeling

Aim: This study aimed the description of a protocol to acquire a 3D finite element (FE) model of a human maxillary central incisor tooth restored with ceramic crowns with enhanced geometric detail through an easy-to-use and low-cost concept and validate it through finite element analysis (FEA). Methods: A human maxillary central incisor was digitalized using a Cone Beam Computer Tomography (CBCT) scanner. The resulted tooth CBCT DICOM files were imported into a free medical imaging software (Invesalius) for 3D surface/geometric reconstruction in stereolithographic file format (STL). The STL file was exported to a computer-aided-design (CAD) software (SolidWorks), converted into a 3D solid model and edited to simulate different materials for full crown restorations. The obtained model was exported into a FEA software to evaluate the influence of different core materials (zirconia - Zr, lithium disilicate - Ds or palladium/silver - Ps) on the mechanical behavior of the restorations under a 100 N applied to the palatal surface at 135 degrees to the long axis of the tooth, followed by a load of 25.5 N perpendicular to the incisal edge of the crown. The quantitative and qualitative analysis of maximum principal stress (ceramic veneer) and maximum principal strain (core) were obtained. Results: The Zr model presented lower stress and strain concentration in the ceramic veneer and core than Ds and Ps models. For all models, the stresses were concentrated in the external surface of the veneering ceramic and strains in the internal surface of core, both near to the loading area. Conclusion: The described procedure is a quick, inexpensive and feasible protocol to obtain a highly detailed 3D FE model, and thus could be considered for future 3D FE analysis. The results of numerical simulation confirm that stiffer core materials result in a reduced stress concentration in ceramic veneer

Oral candidiasis and denture stomatitis in diabetic patients: Systematic review and meta-analysis

Abstract Here, the prevalence of oral candidiasis and denture stomatitis among diabetic patients compared to healthy ones was summarized through a systematic review with meta-analysis. Medline, Scopus, Web of Science, Lilacs, Cochrane Library, Embase, and the grey literature were searched without restriction, until May 2020. Eligibility criteria were established, data were extracted, and quality assessment was conducted by two trained examiners. Qualitative synthesis was based on the recommendations of Fowkes and Fulton. Two meta-analyses were performed on studies investigating patients with: a) oral candidiasis and b) denture stomatitis. Out of 6034 screened studies, seven were eligible for qualitative and quantitative synthesis; of these, three evaluated oral candidiasis and four evaluated denture stomatitis. Qualitative synthesis showed that the main methodological problems of the studies included sample size, source of controls, matching, and randomization. Diabetic patients had a similar chance of developing oral candidiasis to non-diabetic patients (OR1.40 [0.96; 2.04], p = 0.08, I2 = 94%). However, diabetic patients had a higher chance to present denture stomatitis compared to non-diabetic patients (OR 1.92 [1.42, 2.59] p < 0.0001, I2 = 0%). Therefore, diabetic patients have a higher chance of developing denture stomatitis compared to non-diabetic patients. However, for all analyses, the certainty of the evidence was considered to be very low.

Effect of Silicon dioxide coating of acrylic resin surfaces on Candida albicans adhesion

Abstract Acrylic resin has been used in the manufacture of prostheses, however, in the oral cavity, this material starts to retain microorganisms capable of causing gingival inflammation due its porosities. The aim of this study was to evaluate the influence of the use of silicon dioxide as a coating layer applied onto acrylic resin, on the adhesion of Candida albicans (Ca). After the incubation period in Sabouraud Dextrose Broth, a total of 1 ml of the Ca suspension was added to plate wells, each well containing a specimen of acrylic resin. The adhesion ability of Ca on acrylic resin was determined by counting colonies. Three groups (n = 6) of acrylic resin were assessed: with polishing (RP); without polishing (RW); with polishing and coating layer of silicon dioxide (RPC). Ca deposited on the surface of the acrylic resin was also observed using Scanning Electron Microscopy (SEM). Statistical assessment by Kruskal-Wallis and Student-Newman-Keuls Method were done (α = 2%). There was significant difference among the groups. The RPC group showed the lowest growth, with an average of 5.59 Log CFU/cm 2 ; there was a statistically significant difference in relation to group RW, which presented a growth of 6.07 Log CFU/cm 2 and to group RP with 5.91 Log CFU/cm 2 (p < 000.1). SEM images demonstrated that in the RP and RPC group, the surface of the resin had greater regularity, and smaller number of microorganisms. The application of silicon dioxide coating on acrylic resin appears to be a promising alternative, and its use can help in reducing the adhesion of Ca in prostheses.

Does traumatic occlusal forces lead to peri-implant bone loss? A systematic review

Abstract Observational studies have indicated that crestal bone level changes at implants are typically associated with clinical signs of inflammation, but still mechanical overload has been described as possible factor leading to hard-tissue deficiencies at implant sites without mucosal inflammation. The aim of this paper was systematically review the literature regarding the possible effect of traumatic occlusal forces on the peri-implant bone levels. Literature search was conducted using PubMed, Scielo and Lilacs, including the following terms: oral OR dental AND implant$ AND (load OR overload OR excessive load OR force$ OR bruxism) AND (bone loss OR bone resorption OR implant failure$). Databases were searched for the past 10 years of publications, including: clinical human studies, either randomized or not, cohort studies, case control studies, case series and animal research. Exclusion criteria were review articles, guidelines and in vitro and in silico (finite element analysis) research, as well as retrospective studies. The PICO questions formulated was: "does traumatic occlusal forces lead to peri-implant bone loss?" The database searches as well as additional hand searching, resulted in 807 potentially relevant titles. After inclusion/exclusion criteria assessment 2 clinical and 4 animal studies were considered relevant to the topic. The included animal studies did not reveal an association between overload and peri-implant bone loss when lower overloads were applied, whereas in the presence of excessive overload it seemed to generate peri-implant bone loss, even in the absence of inflammation. The effect of traumatic occlusal forces in peri-implant bone loss is poorly reported and provides little evidence to support a cause-and-effect relationship in humans, considering the strength of a clinically relevant traumatic occlusal force.

Can implant surfaces affect implant stability during osseointegration? A randomized clinical trial

Abstract This randomized clinical trial evaluated the insertion torque (IT), primary, and secondary stability of dental implants with different surface treatments during the osseointegration period. Nineteen patients with bilateral partial edentulism in the posterior mandibular region were randomly allocated to two implant brand groups and received implants with different surface treatments in the opposite site of the arch: Osseotite and Nanotite or SLA and SLActive. During implant placement, the maximum IT was recorded using a surgical motor equipped with a graphical user interface. The implant stability quotient (ISQ) was assessed immediately after the IT, and was measured weekly via resonance frequency analysis during 3 months. The data were analyzed by a one-way ANOVA, the Bonferroni test, paired t tests and Pearson's correlation coefficient. The IT values were similar (p > 0.05) for all implant types ranging from 43.82 ± 6.50 to 46.84 ± 5.06. All implant types behaved similarly until the 28th day (p > 0.05). Between 35 and 56 days, Osseotite and SLActive showed lower ISQ values (p < 0.001) compared to Nanotite and SLA implants. After 56 days, only Osseotite maintained significantly lower ISQ values than the other implants (p < 0.05). After 91 days the ISQ values were significantly higher than the baseline for all four implant types (p < 0.001). The ISQ and IT values were significantly correlated at the baseline and at the final evaluation for Osseotite, Nanotite, and SLActive implants (p < 0.001). After 91 days, ISQ and IT values were only significantly correlated for the Osseotite implants (p < 0.05). All implants types exhibited acceptable primary and secondary stability.

Misfit and fracture load of implant-supported monolithic crowns in zirconia-reinforced lithium silicate

Abstract Zirconia-reinforced lithium silicate (ZLS) is a ceramic that promises to have better mechanical properties than other materials with the same indications as well as improved adaptation and fracture strength. Objective In this study, marginal and internal misfit and fracture load with and without thermal-mechanical aging (TMA) of monolithic ZLS and lithium disilicate (LDS) crowns were evaluated. Material and methods Crowns were milled using a computer-aided design/computer-aided manufacturing system. Marginal gaps (MGs), absolute marginal discrepancy (AMD), axial gaps, and occlusal gaps were measured by X-ray microtomography (n=8). For fracture load testing, crowns were cemented in a universal abutment, and divided into four groups: ZLS without TMA, ZLS with TMA, LDS without TMA, and LDS with TMA (n=10). TMA groups were subjected to 10,000 thermal cycles (5-55°C) and 1,000,000 mechanical cycles (200 N, 3.8 Hz). All groups were subjected to compressive strength testing in a universal testing machine at a crosshead speed of 1 mm/min until failure. Student's t-test was used to examine misfit, two-way analysis of variance was used to analyze fracture load, and Pearson's correlation coefficients for misfit and fracture load were calculated (α=0.05). The materials were analyzed according to Weibull distribution, with 95% confidence intervals. Results Average MG (p<0.001) and AMD (p=0.003) values were greater in ZLS than in LDS crowns. TMA did not affect the fracture load of either material. However, fracture loads of ZLS crowns were lower than those of LDS crowns (p<0.001). Fracture load was moderately correlated with MG (r=-0.553) and AMD (r=-0.497). ZLS with TMA was least reliable, according to Weibull probability. Conclusion Within the limitations of this study, ZLS crowns had lower fracture load values and greater marginal misfit than did LDS crowns, although these values were within acceptable limits.

Short implants to support mandibular complete dentures - photoelastic analysis

Abstract This study evaluated the stress behavior around short implants in edentulous atrophic mandibles. Six groups included implants with two diameters regular and wide (4 and 5 mm) and three lengths (5, 7 and 9 mm) as follows: Ci9 (9 x 4 mm), Ci7 (7 x 4 mm), Ci5 (5 x 4 mm), Wi9 (9 x 5 mm), Wi7 (7 x 5 mm) and Wi5 (5 x 5 mm). These groups were compared to the control group CG (11 x 4 mm). The analysis was performed with the photoelastic method (n = 6). Each model comprised 4 implants with the same length and diameter connected by a chromium-cobalt bar that simulates a fixed denture. A 0.15 kg force was applied at the end of the cantilever (15 mm), and the maximum shear stress was recorded around the distal and subsequent implants. The stress values were determined, and the quantitative data (Fringes®) were submitted to statistical analysis with one-way ANOVA and the Dunnett test (p < 0.05). It was observed that the reduction in implant length increased stress values with a significant difference (p < 0.05) between CG Ci7 and Ci5, while the increase in implant diameter reduced the stress values without any differences found between short and long implants. Implants with 5 and 7 mm with regular diameter increased stress levels while short implants with larger diameters experienced similar stress to that of longer implants.

Short-term quality of life change perceived by patients after transition to mandibular overdentures

Abstract The aim of this longitudinal observational study was to evaluate the oral health-related quality of life (OHRQoL) following patient rehabilitation with implant-retained mandibular overdentures (IMO) and to identify the contribution of the different domains to OHRQoL. The Oral Health Impact Profile (OHIP-EDENT), Dental Impact on Daily Living (DIDL), and Geriatric Oral Health Assessment Index (GOHAI) questionnaires were completed twice by 25 patients: after 3 months of rehabilitation with complete dentures (CD) and after 3 months of IMO loading using stud abutments. The evaluation after IMO rehabilitation showed significant improvement in three DIDL domains: appearance (p = 0.011), eating and chewing (p = 0.003), and general performance (p = 0.003). The GOHAI results showed significant differences in two domains: psychosocial (p = 0.005) and pain and discomfort (p = 0.0004). The OHIP-EDENT outcomes showed significant improvements in five domains: functional limitation (p = 0.0001), physical pain (p = 0.0002), physical disability (p = 0.0010), and psychological disability and handicap (p = 0.032). The largest observed effect sizes were close to one standard deviation and were observed in the eating and chewing domain (0.93) of the DIDL; the pain and discomfort domain (0.83) of the GOHAI, and the functional limitation (0.89), physical pain (1.02), physical disability (0.84) domains of the OHIP-EDENT. The percentage of satisfied patients increased in all domains. Self-reported OHRQoL of CD wearers was significantly improved after 3 months of treatment with IMO, especially concerning the functional and pain-related aspects.

Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants

Abstract This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical), implant connection (external hexagon, EH or internal hexagon, IH), and occlusal loading (axial or oblique), for both immediately and delayed loaded implants. Analysis of variance at 95%CI was used to evaluate the peak maximum principal stress and strain in bone after applying a 100 N occlusal load. The results showed that the type of prosthetic abutment influences bone stress/strain in only immediately loaded implants. Attachment of conical abutments to IH implants exhibited the best biomechanical behavior, with optimal distribution and dissipation of the load in peri-implant bone.

The effect of fluoride toothpaste on root dentine demineralization progression: a pilot study

The anticaries effect of fluoride (F) toothpaste containing 1100 µg F/g in reducing enamel demineralization is well established, but its effect on dentine has not been extensively studied. Furthermore, it has been shown that toothpaste containing a high F concentration is necessary to remineralize root dentine lesions, suggesting that a 1100 µg F/g concentration might not be high enough to reduce root dentine demineralization, particularly when dentine is subjected to a high cariogenic challenge. Thus, the aim of this pilot study was to evaluate in situ the effect of F toothpaste, at a concentration of 1100 µg F/g, on dentine demineralization. In a crossover and double-blind study, conducted in two phases of 14 days, six volunteers wore a palatal appliance containing four slabs of bovine root dentine whose surface hardness (SH) was previously determined and to which a 10% sucrose solution was applied extra-orally 8×/day. Volunteers used a non-F toothpaste (negative control) or F toothpaste (1100 µg F/g, NaF/SiO2) three times a day. On the 10th and 14th days of each phase, two slabs were collected and SH was determined again. Dentine demineralization was assessed as percentage of SH loss (%SHL). The effect of toothpaste was significant, showing lower %SHL for the F toothpaste group (42.0 ± 9.7) compared to the non-F group (62.0 ± 6.4; p < 0.0001), but the effect of time was not significant (p > 0.05). This pilot study suggests that F toothpaste at 1100 µg F/g is able to decrease dentine caries even under a high cariogenic challenge of biofilm accumulation and sugar exposure.

Mimetização de prótese parcial fixa em caso de fluorose dentária / Partial fixed prosthesis mimicking in case of dental fluorosis

Introdução: O sucesso estético em prótese dentária, seja em reabilitações extensas ou unitárias, se baseia na mimetização da peça protéica. A não percepção da substituição da estrutura dentária perdida é o objetivo atual na Odontologia Restauradora. A presença de manchas ou características específicas torna essa camuflagem mais difícil e, a necessidade de esconder a prótese torna-se um desafio. Descrever a confecção de uma prótese fixa metalocerâmica caracterizada em paciente diagnosticado com fluorose intensa e generalizada. Foi utilizada a técnica da estratificação com representação de manchas opacas através de ranhuras irregulares, bem como o registro fotográfico como método auxiliar na transmissão de informação entre o protesista e o laboratório. A caracterização das manchas se mostrou um método importante a ser considerado na reabilitação bucal, tornando o sorriso mais harmonioso

Introduction: The esthetic success of dental restorations in either extensive or unit cases is based on mimicking the prosthesis. Not percepting the lost tooth replacement is the current objective in restorative dentistry. Additionally, the presence of staining or specifc characteristics makes the dental camouflage more diffcult. In these cases, the need for hiding the prosthesis becomes a challenge. Objective: This report aims to describe the mimicking of a ceramic fxed partial denture in a patient diagnosed with severe and widespread fluorosis. Case report: The layering technique was used in this case, which allowed the characterization of the stains with irregular groves. It was also used the photographic record as an auxiliary method in information transmission between prosthodontist and laboratory. Conclusion: Mimicking of fxed partial denture was showed as an important alternative to be considered in oral rehabilitation, making the smile more harmonious.

Poly (Methyl Methacrylate) absorption and releasing of nystatin and fluconazole / Absorção e liberação de nistatina e fluconazol por polimetilmetacrilato

Objectives: The aim of this study was to verify if there are poly (methyl methacrylate) (PMMA) absorptionand releasing of nystatin (NYS) and fluconazole (FLZ) after simulated treatment of oral candidosis. Materialsand methods: Specimens (30 × 25 × 5 mm) prepared with PMMA polymerized by hot water bath or microwaveenergy were immersed into NYS (3.12 μg/mL), FLZ (2.56 μg/mL) or deionized water (control) during14 days at 35 ± 2 °C. After treatment simulation, specimens were immersed into distilled water during 3, 7, 10and 14 days. The immersion liquid was changed after each analysis. Higher performance liquid chromatographywas used in order to detect antifungal compounds. In order to determine if there was surface depositionof drugs on PMMA resin, specimens were analyzed with electronic microscopy (SEM). Results: None of theantifungal agents was released from the PMMA resins. Conclusion: Within the limitations of this study, itcould be concluded that PMMA resins had no drug absorption with posterior release.

Objetivos: O objetivo deste estudo foi verificar se o poli (metil metacrilato) (PMMA) é capaz de absorver e liberar nistatina (NYS) e fluconazol (FLZ) após simular um tratamento para candidose oral. Materiais e métodos:Espécimes (30 × 25 × 5 mm) foram preparados em resina de PMMA por banho de água quente ou energia demicro-ondas e, em seguida, imersos em solução contendo NYS (3.12 μg/mL), FLZ (2.56 μg/mL) ou água deionizada(controle) durante 14 dias a 35 ± 2 °C. Após a simulação de tratamento, os espécimes foram imersos em água destilada durante 3, 7, 10 e 14 dias. O líquido de imersão foi trocado após cada análise. Cromatografia líquida de alta performance foi utilizada para detectar a presença dos agentes antifúngicos. Para determinar se houve deposição dos agentes antifúngicos na superfície de PMMA, os espécimes foram analisados por microscopia eletrônica de varredura(MEV). Resultados: Não houve liberação de agentes antifúngicos dos espécimes. Conclusão: Considerando as limitações deste estudo, pode-se concluir que a resina de PMMA não absorve ou libera agentes antifúngicos.

Superfícies biomiméticas: novo paradigma da osseointegração / Biomimetic surfaces: new paradigm of osseointegration

O sucesso dos implantes está, frequentemente, associado ao processo de osseointegração. Isso leva a uma busca por tratamentos de superfície para que o titânio se torne cada vez mais bioativo e induza a neoformação óssea. O conceito da superfície biomimética surge com o intuito de gerar uma superfície que module positivamente a osseointegração, de modo que o implante apresente capacidade de osteoindução por meio do reconhecimento biomolecular da superfície. A hidroxiapatita e os fosfatos de cálcio foram os primeiro agentes propostos para o biomimetismo da superfície com o tecido ósseo; no entanto, hoje é proposta a utilização de proteínas da matriz extracelular óssea e fatores de crescimento para mimetizar a fisiologia do tecido e aumentar ainda mais a previsibilidade dos implantes. Quando os resultados das pesquisas puderem ser traduzidos em projetos industriais, novas superfícies podem surgir no mercado, garantindo maior segurança para a instalação de implantes em sítios ósseos desfavoráveis e o carregamento oclusal precoce.

Dental implants success is often associated with the osseointegration process. To induce the bone formation, there is a search for surface treatments to create a more bioactive titanium. The concept of biomimetic surface arises in order to generate a surface that positively modulates the implant osseointegration, presenting osteoinductive capacity through the biomolecular recognition of the surface. Hydroxyapatite and calcium phosphates were the first agents proposed for surface coating to mimic the bone tissue; however. the use of bone extracellular matrix proteins and growth factors have been proposed to mimic the physiology of the tissue and further increase its predictability. When the research results become translated into industrial projects, new surfaces may emerge in the market providing greater security for implants installation in unfavorable bone sites and early occlusal loading.

Occlusal force, electromyographic activity of masticatory muscles and mandibular flexure of subjects with different facial types

OBJECTIVE: The aim of this study was to evaluate whether vertical facial patterns influence maximal occlusal force (MOF), masticatory muscle electromyographic (EMG) activity, and medial mandibular flexure (MMF). MATERIAL AND METHODS: Seventy-eight dentate subjects were divided into 3 groups by Ricketts's analysis: brachyfacial, mesofacial and dolychofacial. Maximum occlusal force in the molar region was bilaterally measured with a force transducer. The electromyographic activities of the masseter and anterior temporal muscles were recorded during maximal voluntary clenching. Medial mandibular flexure was calculated by subtracting the intermolar distance of maximum opening or protrusion from the distance in the rest position. The data were analyzed using ANOVA followed by Tukey's HSD test. The significance level was set at 5 percent. RESULTS: Data on maximum occlusal force showed that shorter faces had higher occlusal forces (P<0.0001). Brachyfacial subjects presented higher levels of masseter electromyographic activity and medial mandibular flexure, followed by the mesofacial and dolychofacial groups. Additionally, dolychofacial subjects showed significantly lower electromyographic temporalis activities (P<0.05). CONCLUSION: Within the limitations of the study, it may be concluded that maximum occlusal force, masticatory muscle activity and medial mandibular flexure were influenced by the vertical facial pattern.

Influence of female hormonal fluctuation on maximum occlusal force

Hormonal fluctuations during the menstrual cycle may influence on muscular tensions and probably alter occlusal force. The aim of this study was to evaluate whether hormonal levels affect maximum occlusal force (MOF) of healthy women throughout the different phases of the menstrual cycle. Sixty complete dentate subjects who were not under use of oral contraceptives were selected to participate in this study. MOF was bilaterally evaluated on the molar region, during 3 complete menstrual cycles, using 5.65 mm-wide sensors. Measurements were carried out during each of the following menstrual cycle phases: menstrual, follicular, periovulatory and luteal, presumed by ovulation test. Data were analyzed by one-way ANOVA and Tukey-Kramer test (p<0.05). Comparisons among menstrual cycle phases showed no differences on MOF (p=0.27). Under the conditions of this study, it may be concluded that hormonal fluctuations during the menstrual cycle do not affect MOF of a sample of healthy women.

As flutuações hormonais durante o ciclo menstrual podem influenciar as tensões musculares e possivelmente alterar a força oclusal. O objetivo deste estudo foi avaliar se os níveis hormonais afetam a força máxima oclusal (FMO) de mulheres saudáveis durante as diferentes fases do ciclo menstrual. Sessenta pacientes completamente dentadas que não usavam contraceptivos orais foram selecionadas para participar neste estudo. FMO foi avaliada bilateralmente na região dos molares, durante 3 ciclos menstruais completos, utilizando sensores de 5,65 mm de espessura. As mensurações foram realizadas durante cada fase do ciclo menstrual: menstrual, folicular e lútea periovulatória, identificadas por teste ovulatório. Os dados foram analisados por ANOVA um critério seguido do teste de Tukey-Kramer (p<0,05). As comparações entre as fases do ciclo menstrual não apresentaram diferenças na FMO (p=0,27). Segundo as condições deste estudo, pode-se concluir que as flutuações hormonais durante o ciclo menstrual não afetaram a FMO de mulheres saudáveis.

Long-term efficacy of denture cleansers in preventing Candida spp. biofilm recolonization on liner surface

This study evaluated the long-term efficacy of denture cleansers against Candida spp. biofilm recolonization on liner surface. Specimens were fabricated of a poly(methyl methacrylate)-based denture liner and had their surface roughness evaluated at baseline and after cleansing treatments. C. albicans or C. glabrata biofilms were formed on liner surface for 48 h, and then the specimens were randomly assigned to one of cleaning treatments: two alkaline peroxides (soaking for 3 or 15 min), 0.5 percent sodium hypochlorite (10 min) or distilled water (control; 15 min). After the treatments, the specimens were sonicated to disrupt the biofilm, and residual cells were counted (cell/mL). Long-term effectiveness of the cleaning processes was determined by submitting a set of cleaned specimens to biofilm growth conditions for 48 h followed by estimation of cell counts. The topography of specimens after cleaning treatments was analyzed by SEM. Data were analyzed by ANOVA and Tukey's test (α; = 0.05). Results of cell count estimation showed significant differences in cleanliness among the treatments (p < 0.001), and it could be observed by SEM. However, no significant difference (p > 0.05) was observed among the Candida species regarding the recolonization condition. Alkaline denture cleansers showed similar cleaning performance and both differed from the control (p < 0.001). Sodium hypochlorite was the only treatment that removed biofilm efficiently, since no viable cells were found after its use. In conclusion, alkaline peroxide denture cleansers were not effective in removing Candida spp. biofilm from denture liner surfaces and preventing biofilm recolonization.

Fixed partial dentures in an up to 8-year follow-up

Information on the longevity of fiber-reinforced composite fixed partial dentures (inlay FPDs) should be considered in the selection of materials, operative techniques and patient instructions related to prognosis and long-term cost-effectiveness. OBJECTIVE: This study evaluated the long-term survival of fiber-reinforced, adhesively-bonded composite prostheses placed in posterior teeth. Materials and Methods: Twenty-one patients that received adhesively bonded polyethylene inlay FPDs in posterior teeth were selected from a private practice dental office and invited to evaluation. Of the eligible 21 patients, 13 (mean age 50.3 ± 11.5 years) agreed to be enrolled as participants, providing 22 restorations, as several subjects presented more than one inlay FPD. One dentist placed all inlay FPDs using Ribbond as reinforcement and Tetric Ceram/Durafil or Charisma/Renamel composite combinations, according to manufacturer's instructions. Two independent calibrated operators performed the evaluation, using modified USPHS criteria. Survival functions of restorations were analyzed with Kaplan-Meier and Log Rank test (α = 0.05). RESULTS: The majority of restorations received A or B scores. Four (18.2 percent) inlay FPDs fractured among the 22 evaluated. The mean estimate survival rate was 7 years (95 percent CI: 5.9 to 8.1), and the overall percentage of survival was 81.8 percent. There were no significant differences (p>0.05) between composite combinations or tooth location considering all clinical aspects evaluated and survival functions. CONCLUSION: Posterior fiber-reinforced fixed partial dentures exhibited acceptable clinical performance after a period up to 8 years.