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.

Resumo Este estudo observacional transversal com 24 participantes teve como objetivo avaliar as diferenças na força de mordida (FM) e na PM (performance mastigatória) entre usuários de prótese total convencional (PTC) e de overdenture mandibular (OM) e a correlação entre essas variáveis. O teste de FM foi realizado bilateralmente com um dispositivo de força oclusal. Durante o teste de PM, os pacientes foram solicitados a mastigar uma porção padronizada de Optocal por 40 ciclos mastigatórios. O teste de Shapiro Wilk foi empregado para verificar a normalidade dos dados, o teste T de Student para identificar diferenças entre os grupos e os coeficientes de correlação de Pearson para investigar inter-relações entre variáveis. Uma regressão linear múltipla foi realizada pelo método stepwise. Valores de p≤0,05 foram considerados estatisticamente significantes. Diferentemente dos usuários de OM, os usuários de PTC apresentaram uma diferença significativa (34%) na FM entre o lado dominante e o não dominante (p=0,04). Os usuários de OM apresentaram FM significativamente maior (p=0,01) sem apresentar um lado dominante (p=0,38) e obtiveram PM significativamente melhor nos seguintes parâmetros: os valores de PMX50 diminuíram 27,25% (p=0,01), PMB diminuiu em 48,38% (p=0,01), e EM 5.6 diminuiu 53,25% (p=0,02), enquanto EM2.8 aumentou 151,57% (p=0,01). A FM e PMX50 no grupo de usuários da IMO foram negativamente correlacionados (-0,57;p=0,05); esse coeficiente de correlação foi o único parâmetro incluído no modelo de regressão multivariada. Os usuários da OM possuem maior FM e melhor performance mastigatória do que os usuários de PTC, observados principalmente na redução do tamanho das partículas mastigadas. A PM está correlacionada com um maior FM nos usuários da OM através de uma melhor trituração de partículas.

Abstract: This cross-sectional observational study with 24 patients evaluated differences in bite force (BF) and masticatory performance (MP) between conventional complete denture (CCD) and implant mandibular overdenture (IMO) users and the correlation between these variables. The BF test was performed bilaterally with an occlusal force device. During the MP test, patients were asked to chew Optocal particles for 40 cycles. The Shapiro Wilk test was employed to verify the normality of the data, the student t test to identify differences between groups, and Pearson’s correlation to investigate interrelationships between variables. A multiple linear regression was subsequently performed via the stepwise method. P values ≤0.05 were considered statistically significant. Unlike IMO users, CCD users presented a significant difference (25.6%) in BF between the dominant and non-dominant chewing side (p=0.04). IMO users presented significantly higher BF (p=0.01) without presenting a dominant side (p=0.38), and also performed significantly better for the following MP parameters: MPX50 values decreased by 27.25% in IMO users (p=0.01), MPB decreased by 48.38% (p=0.01), and ME 5.6 decreased by 53.25% (p=0.02), while ME2.8 increased by 151.57% (p=0.01). The BF and MPX50 in the IMO wearers group were negatively correlated (-0.57; p=0.05); this correlation coefficient was the only parameter included in the multivariate regression model. IMO users have higher BF and better masticatory performance than CCD users, especially in terms of chewed particles size reduction. MP is correlated with a higher BF in IMO users through better particle trituration.

Resumo Este estudo avaliou a influência da altura da porção transmucosa do pilar protético com junção cone morse e do comprimento dos implantes no comportamento biomecânico coroas unitárias com diferentes proporção coroa-implante. Seis modelos virtuais (S11, M11, L11, S13, M13 e L13) foram construídos combinando pilares protéticos com transmucoso considerado: curto (S: 2,5 mm), médio (M: 3,5 mm) ou longo (L: 4,5 mm) com diferentes comprimentos de implantes (11 ou 13 mm). Um incisivo central superior de 11 mm de altura foi construído para cada pilar. Cada conjunto foi posicionado em um modelo de osso virtual e exportado para análise matemática. Uma malha de 0,60 mm foi criada após análise de convergência e uma carga de 49 N foi aplicada ao cíngulo da coroa em um ângulo de 45°. A distribuição de estresse gerada por carga foi analisada nos componentes protéticos de acordo com o critério de tensão de von Mises (σvM) e no osso cortical e medular por meio da tensão de cisalhamento (εmax). O uso de pilares com porção transmucosa mais longa (L11) aumentou a tensão no pilar protético em 250%, e resultou em tensões 40% maiores no parafuso e 92% no osso cortical em relação aos pilares com transmucoso curto (S11). O aumento do comprimento do implante produziu uma ligeira redução da tensão de cisalhamento no osso cortical. O osso medular não foi afetado pela relação coroa-implante. Pilares protéticos com porção transmucosa mais longa concentram tensões no implante e no osso cortical, quando a proporção coroa-implante é aumentada.

Abstract This in silico study evaluated the influence of the abutment collar height and implants length on the biomechanical behavior of morse taper single dental implants with different crown-to-implant ratio. Six virtual models were constructed (S11, M11, L11, S13, M13 and L13) by combining short (S: 2.5 mm), medium (M: 3.5 mm) or long (L: 4.5 mm) abutment collar heights with different implant lengths (11 or 13-mm). An upper central incisor of 11-mm height was constructed on top of each abutment. Each set was positioned in a virtual bone model and exported to analyze mathematically. A 0.60-mm mesh was created after convergence analysis and a 49 N load was applied to the cingulum of the crown at an angle of 45°. Load-generated stress distribution was analyzed in the prosthetic components according to von Mises stress criteria (σvM) and in the cortical and cancellous bone by means of shear stress (εmax). The use of longer collar abutments (L11) increased the stress on the abutment by 250% and resulted in 40% higher stresses on the screw and 92% higher cortical shear stresses compared to short collared abutments (S11). Increasing the implant length produced a slight stress reduction on cortical bone. Cancellous bone was not affected by the crown-to-implant ratio. Longer abutment collars concentrate stresses at the implant level and cortical bone by increasing the crown-to-implant ratio.

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.

Abstract Several instruments have been used to measure oral health-related quality of life (OHRQoL). The Oral Health Impact Profile (OHIP) questionnaire was based on the concept that sequential events related to oral diseases can cause discomfort, functional limitations and consequently, result in dysfunctions and even disabilities. There are few studies in the literature that structurally analyze the instruments to verify whether they measure the requirements to which they were designed to. The objective of the study was to evaluate the internal structure of the OHIP-Edent questionnaire. The OHIP-Edent was administered to 54 edentulous patients’ wearers of conventional complete dentures. For structural analysis, an exploratory factorial analysis (EFA) was carried out. After determining the internal consistency of the model (Cronbach’s alpha = 0.88), the fit was checked using the root mean square error approach (value 0.04), the comparative fit index (value 0.982) and the Tucker-Lewis index (value 0.976). After analysis of the 19 questions and the seven domains proposed in the OHIP-Edent questionnaire, the hypothetical factorial model showed three dimensions denominated “Physical Impact”, “Psychological Impact” and “Social Impact”. In this sample of conventional complete denture wearers, the OHIP-Edent seems adequate to measure the “Physical Impact”, “Psychological Impact”, and “Social Impact” of the OHRQoL. The confirmatory factorial analysis confirmed the model and, through adjustment indexes, it was verified that the three dimensions have convergence and consistence adequate in order to characterize the OHRQoL construct with validity.

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.

As bases proteticas em resina acrilica podem sofrer alteracao de cor com o tempo em funcao do acumulo de pigmentos em seu interior, porem ha carencia de informacao sobre o efeito do consumo de chimarrao neste processo. Este trabalho avaliou o efeito de cinco bebidas diferentes, incluindo chimarrao, na cor de resinas acrilicas processadas por tres tecnicas diferentes. Vinte e cinco discos de resina acrilica (3 mm de espessura x 20 mm de diametro) foram fabricados a partir de cada uma das tecnicas de processamento (P1 - polimerizacao por microondas / resina termopolimerizavel por microondas; P2 - termopolimerizacao convencional / resina termopolimerizavel convencional e P3 - polimerizacao por microon - das / resina termopolimerizavel convencional). Os discos foram aleatoriamente divididos em cinco (n=5) grupos por tecnica: G1 - agua; G2 - refrigerante a base de cola; G3 - cafe; G4 - chimarrao e G5 - vinho tinto, e foram mantidos imersos em cada uma das respectivas solucoes por 30 dias a 37 ºC, com trocas das solucoes a cada 3 dias. A cor final foi medida na escala CIE-L*a*b* com um colorimetro Konica-Minolta CR-10 e comparada com os valores originais de L*a*b* previos a imersao de cada corpo-de-prova. Analise de Variancia para dois fatores nao encontrou diferencas entre as tecnicas e apontou diferenca estatisticamente significativa (p<0,05) entre as solucoes. Teste complementar de Tukey mostrou que as menores variacoes de cor ocorreram para agua e refrigerante a base de cola; o cafe apresentou a segunda menor variacao de cor; o chimarrao apresentou a segunda maior variacao enquanto a maior variacao de cor foi encontrada para o vinho tinto. Conclusoes: Concluiu-se que quase toda solucao utilizada provoca mudanca de cor nas resinas acrilicas, principalmente com chimarrao e vinho, consideradas distinguiveis por profissionais e clinicamente inaceitaveis respectivamente.

Denture bases may undergo color change over time induced by pigment accumulation within their body; however there is a lack of information regarding the role of yerba mate tea in this process. This work evaluated the effect of five common beverages, including yerba mate tea, on color changes of acrylic denture base resins processed in three different ways. Three different processing techniques were used (P1 - microwave irradiation / microwave activated resin; P2 - heat polymerization / conventional heat activated resin and P3 - microwave irradiation / conventional heat polymerized resin) to make twenty five resin discs each (3.0 mm thick x 20 mm diameter), totaling seventy-five resin discs. The discs made with each technique were randomly divided into five groups (n=5) and placed in the following solutions: G1-water; G2-cola; G3-coffee; G4- yerba mate tea; G5- red wine, for 30 days at 37ºC. The solutions were renewed every 3 days. Color change on the CIE-L*a*b* scale was measured with a Konica- Minolta CR-10 colorimeter and compared with original L* a* and b* values of each specimen prior to immersion. Data were analyzed using 2-way ANOVA, and showed no difference among techniques and significant statistical differences among solutions (p<0.05). Tukey's post-hoc test showed that the lowest color changes were for water and cola, which were undistinguishable from each other; coffee produced the second lowest color change; yerba mate tea produced second greatest color change, while the greatest color change was produced by red wine. Within the limitations of this study, it was concluded that almost all the solutions used can change color in acrylic resin, especially yerba mate tea, considered distinguishable by professionals, and red wine, considered distinguishable by patients and clinically unacceptable.

Craniofacial dimensions influence oral functions; however, it is not known whether they are associated with function asymmetry. The objective of this study was to evaluate chewing side preference and lateral asymmetry of occlusal contact area and bite force of individuals with different craniofacial patterns. Seventy-eight dentate subjects were divided into 3 groups according to the VERT index as follows: (1) mesofacial, (2) brachyfacial and (3) dolichofacial. Chewing side preference was evaluated using jaw tracking equipment, occlusal contact area was measured by silicon registration of posterior teeth, and bite force was measured unilaterally on molar regions using 2.25 mm-thick sensors. Statistical analysis was performed using ANOVA on Ranks, Student's t-test, and Mann-Whitney tests at a 5% significance level. Mesofacial, brachyfacial, and dolichofacial subjects presented more occlusal contact area on the left side. Only dolichofacial subjects showed lateral asymmetry for bite force, presenting higher force on the left side. No statistically significant differences were found for chewing side preference among all groups. Within the limitations of this study, it can be concluded that craniofacial dimensions play a role in asymmetry of bite force. ClinicalTrials.gov ID: NCT01286363.

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%. 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.

This study evaluated accuracy of fit, impact strength, types and morphology of fractures of a microwave acrylic resin polymerized with a cycle alternative to that recommended by the manufacturer. Onda Cryl was polymerized according to the manufacturer's instructions (MC), 3 min at 360 W, 4-min pause, and 3 min at 810 W; and with an alternative cycle (AC) of 6 min at 630 W. Accuracy of fit was measured at 3 points at the right (A) and left (B) ridge crests and at the midline (C) on the posterior palatal seal for each denture base (n = 10/group). The measurements were taken immediately after finishing and after 30-day storage in water. The impact strength test (Charpy method) was performed with a 40 kJ/cm load (n = 20/group). Fractographic analysis was accomplished for all fragments and the fracture types were characterized by means of their morphology, crack propagation angles and microstructure. Accuracy of fit data were analyzed by ANOVA, impact strength and radius values were compared by the t test, and the fractographic analysis data, by the Wilcoxon Mann-Whitney test. The significance level was fixed at p < 0.05. No statistical differences were found between the two cycles of polymerization used. However, after the 30-day storage period in water, the denture bases showed better fit (P < .05). Most of the fractures were classified as brittle (MD: 70%, AC: 80%). Based on the results of this study, it could be concluded that both polymerization cycles are adequate to polymerize the denture resin studied.

O objetivo deste estudo foi verificar alterações nos movimentos mandibulares durante a pronúncia dos fonemas /m/ e /s/ da língua portuguesa, em pacientes com desgaste dental incisal antes a após a instalação de placas interoclusais e restauração dos dentes. Os voluntários foram divididos em grupo controle, composto por pacientes dentados, e grupo experimental composto por pacientes com desgastes incisais devido ao bruxismo. Desvios laterais para direita e esquerda, e de abertura foram mensurados por meio do método eletromagnético do registro do traçado mandibular durante a pronúncia dos fonemas /m/ e /s/. As avaliações foram realizadas 1 semana e imediatamente antes da instalação de placas interoclusais; 24 h, 7, 30 e 60 dias após a instalação das mesmas, e 1 semana e 1 mês após a restauração dos dentes. Os resultados foram submetidos à ANOVA a dois critérios e testes de Mann-Whitney e Friedman t (p<0,05). O movimento de abertura foi diferente (p<0,05) para ambos os sons em todos os períodos avaliados. Houve diferença (p<0,05) na amplitude anteroposterior durante pronúncia do som /s/ imediatamente antes e 1 mês após a instalação da placa. O desvio lateral para o lado direito apresentou diferença (p<0,05) entre grupos durante a pronúncia do /s/ em todos os períodos após a inserção da placa, e 1 mês e 2 meses após a inserção da mesma para o som /m/. Pacientes com desgaste dental anterior apresentaram amplo movimento de abertura, e movimentos mandibulares durante a pronúncia dos sons /m/ e /s/ não foram alterados após a instalação de placa e restauração dos dentes.

This study described changes in mandibular movements during pronunciation of /m/ and /s/ sounds in Portuguese, in patients presenting dental wear before and after appliance insertion and tooth reconstruction. Subjects were divided into a control group of dentate patients and an experimental group of patients with incisal tooth wear due to bruxism. A magnetic jaw tracking device measured the jaw opening, and translations to left and right sides of the mandible during pronunciation of phonemes. Evaluations were carried out 1 week and immediately before appliance insertion; 24 h, 7, 30 and 60 days after appliance insertion; and 1 week and 1 month after tooth reconstruction. Data were submitted to two-way ANOVA, Mann-Whitney and Friedman tests (p<0.05). Jaw opening was different (p<0.05) for both sounds in all periods. The anteroposterior amplitude for /s/ showed differences immediately before and 1 month after appliance insertion (p<0.05). Lateral amplitude for the right side showed differences between groups after appliance insertion for /s/, and 1 and 2 months after appliance insertion for the /m/ (p<0.05). Volunteers with anterior tooth wear had a wider opening movement, and the movements during speech of /m/ and /s/ sounds were not changed after appliance insertion and reconstruction of teeth.

O objetivo deste estudo foi avaliar a energia livre de superfície (ELS), rugosidade superficial (RS) e dureza de superfície (DS) de dois materiais disponíveis comercialmente para fabricação de "abutments" de implante. Em acréscimo, os espécimes foram investigados por microscopia eletrônica de varredura (MEV) para determinar a morfologia de superfície. Vinte e cinco discos de ligas de Ti-6Al-4V e Tilite (Ni-Cr-Ti) (5 x 2 mm) foram usados neste estudo. A energia livre de superfície foi determinada pela mensuração do ângulo de contato formado entre uma gota de água destilada e deionizada e a superfície do espécime para cada material. A rugosidade superficial foi mensurada com uso de um rugosímetro e a dureza de superfície foi avaliada por meio do teste de microdureza Vickers. Os dados foram analisados usando Análise de variância (P < 0,05). Foram encontradas diferenças significantes (P < 0,05) para os valores de ELS e RS entre Ti-6Al-4V (36,2 erg.cm-2; 0,2 µm) e Tilite (30,9 erg.cm-2; 0,16 µm). Entretanto, os valores de dureza de superfície não foram diferentes para ambos os materiais (Ti-6Al-4V - 325,0 kg/mm² e Tilite - 324,3 kg/mm²) (P > 0,05). A análise topográfica dos materiais pela MEV revelou superfícies diferentes. Dentro das limitações deste estudo, concluiu-se que as ligas de Ti-6Al-4V e Tilite mostraram diferenças nas propriedades de superfícies, exceto dureza, sugerindo que ambas as ligas são adequadas para a confecção de "abutments". Entretanto, estudos são necessários para evidenciar as respostas biológicas aos "abutments" de implantes confeccionados com essas ligas.

The aim of this study was to evaluate surface free energy (SFE), surface roughness (SR) and surface hardness (SH) of two commercially available materials for fabricating dental implant abutments. In addition, the specimens were investigated by scanning electron microscopy (SEM) to determine the surface morphology. Twenty five discs (5 x 2 mm) of Ti-6Al-4V and Tilite (Ni-Cr-Ti) alloys were used in this study. Surface free energy was determined by the contact angle formed between a drop of distilled, deionized water and the surface of the specimen of each material. The surface roughness was measured with a mechanical profilometer and the surface hardness was evaluated by means of the Vickers hardness micro indentation test. SFE, SR and SH data were analyzed using one-way ANOVA (p < 0.05). Statistical differences (p < 0.05) were found between Ti-6Al-4V (36.2 erg.cm-2; 0.2 µm) and Tilite (30.9 erg.cm-2; 0.16 µm) for SFE and SR. However, the differences between the surface hardness values of Ti-6Al-4V (325.0 kg/mm²) and Tilite (324.3 kg/mm²) were not statistically significant (p > 0.05). Evaluations by SEM revealed different surface morphology. Within the limits of this study, it can be concluded that the Ti-6Al-4V and Tilite alloys showed differences in surface properties, except for surface hardness, suggesting that both alloys may be considered appropriate for producing abutments. Further studies are, however, necessary to elucidate the biological responses to implant abutments made with these alloys.