Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever) had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments

Confiabilidade de um método de imagem digital para medição de deflexão mandibular medial em adultos dentados

Medial mandibular flexure (MMF) is the functional approximation of hemi-mandibles in jaw opening and protrusion, which may affect conventional or implant-supported arch prostheses. OBJECTIVE: This study evaluated the intra- and inter-rater reliability of a digital image method for linear measurement of MMF in dentate subjects. MATERIAL AND METHODS: Mandibular occlusal impressions in vinyl polysiloxane during rest and maximum opening were obtained from seven adult volunteers. Each impression and the Mitutoyo digital calipers with a 10mm opening were scanned at a 200% magnification. The images were processed using Adobe Photoshop software to get reference points on contralateral first molars. Linear intermolar measurements were taken using the Image Tool software (UTHSCSA), which was calibrated with the standard opening of the digital calipers. Intermolar distance was measured in triplicate for each image by two independent examiners. MMF was calculated by subtracting the intermolar distance in maximum opening (or protrusion) from the distance in rest position. Data were analyzed by intraclass correlation (ICC) tests for estimating intra- and inter-rater reliability. RESULTS: MMF values ranged from -0.21 to 0.44mm. Intra-rater ICCs were 0.982 and 0.993, and inter-rater ICC was 0.696. CONCLUSION: The present results show excellent intra-rater and good inter-rater reliability of this digital image method for measuring MMF in dentate subjects.A deflexão mandibular medial (MMF) é uma deformação funcional que ocorre com a aproximação das hemi-mandíbulas em abertura e protrusão, podendo afetar próteses convencionais e implanto-suportadas em arco. OBJETIVOS: Este trabalho avaliou a confiabilidade intra- e inter-examinador de um método de imagem digital para aferição linear da MMF. MATERIAL E MÉTODOS: Foram selecionados sete voluntários adultos dentados, obtendo-se registros oclusais inferiores de silicona de adição em repouso, abertura e protrusão máximas. Os registros foram escaneados juntamente com um paquímetro Mitutoyo com abertura de 10mm num aumento de 200%. A imagem foi processada no programa Adobe Photoshop obtendo-se pontos de referência intermolares, e as medições lineares foram feitas no programa ImageTool (UTHSCSA) calibrado com a medida padrão do paquímetro. Foram feitas medições em triplicata da medida da distância intermolar para cada imagem. A MMF foi calculada subtraindo-se a distância intermolar em abertura da distância em repouso/ protrusão. Os dados foram analisados por coeficientes de correlação intraclasse (ICC) para estimar a confiabilidade intra- e inter-examinadores. RESULTADOS: Os valores de MMF variaram de -0,21 a 0,44mm. Os ICCs intra-examinador foram 0,982 e 0,993, e o ICC inter-examinador foi 0,696. CONCLUSÃO: Os resultados demonstram excelente confiabilidade intra-examinador e boa confiabilidade inter-examinador deste método de imagem digital para aferição de MMF em adultos dentados

Quality of life and mastication in denture wearers and cleft lip and palate adults

<div><p>Abstract The impact of oral rehabilitation on masticatory function and oral health-related quality of life (OHRQoL) may vary with the experience of the individual with tissue loss. Our hypothesis is that patient-centered outcomes vary among adults who have experienced large defects in the maxilla due to congenital or acquired conditions even after oral rehabilitation to restore aesthetics and function. This study compared OHRQoL, perceived masticatory ability, maximum bite force (MBF), and symptoms of pain and depression among subjects with acquired (edentulous maxilla) and congenital (cleft lip and palate) loss of oral tissues in the maxilla after dental treatment. A gender-matched sample (n = 60) of cleft lip and palate (CLP), maxillary denture wearers (DENT) and controls (CONT) was recruited. OHRQoL was assessed using OHIP-14. Chewing was evaluated through a masticatory ability questionnaire and by MBF. The RDC/TMD Axis II questionnaire was used to assess symptoms of pain and depression. Data were analyzed by Fisher's test, Kruskal Wallis test, and Spearman correlation coefficients. CLP showed higher OHIP-14 and depression scores than DENT and CONT (p < 0.05). Sub-analysis by OHIP-14 items (%FOVO) showed higher prevalence of psychological impact for CLP and of functional impacts for DENT. The number of foods difficult to chew, of food textures difficult to chew, and avoided foods were similar between CLP and DENT. OHIP-14, MBF, and depression scores showed significant correlation (p < 0.05). The results suggest that adults with treated CLP or maxillary DENT have chewing impairment and lower MBF than healthy subjects, with different psychological and functional impacts.</p></div

Adaptação de bases de próteses totais submetidas a polimento químico

OBJECTIVE: This study evaluated the effect of chemical polishing on the internal adaptation of complete denture bases fabricated with Veracril® resin and polymerized by either the conventional (C) or microwave (M) techniques. MATERIAL AND METHODS: Six groups (n=6/group) were tested: 1) C + no polishing (CO); 2) C + chemical polishing (CQ); 3) C + immersion in hot water at 75&ordm;C (CW); 4) M + no polishing (MO); 5) M + chemical polishing (MQ); and 6) M + immersion in hot water at 75&ordm;C (MW). Internal adaptation immediately after the polishing treatment and after 30 days of storage in water at 37&ordm;C was evaluated by weighing a vinyl polysiloxane film reproducing the gap between resin base and metallic master model, using a precision scale. Data were analyzed by ANOVA and Tukey test and paired Student's t test, at a significance level of 0.05. RESULTS: No significant difference in immediate adaptation was found as a function of technique, polishing treatment, or interaction of technique/polishing. After 30 days, adaptation means (g) were: CO=2.46&plusmn;0.32 a; CQ=3.40&plusmn;0.23 d; CW=3.14&plusmn;0.22 c; MO=3.23&plusmn;0.37 c, d; MQ=3.41&plusmn;0.47 d; MW=2.81&plusmn;0.33 b (means followed by different letters are statistically different at alpha=0.05). All groups but group CO had significant increase of misfit over the tested period. CONCLUSION: The present results suggest that Veracril® resin denture bases submitted to chemical polishing had decrease of internal adaptation in 30 days, although immediate adaptation was not affected.OBJETIVO: Este trabalho avaliou o efeito do polimento químico sobre a adaptação interna de bases de próteses totais confeccionadas em resina acrílica ativada termicamente Veracril® polimerizada por técnica convencional (C) ou por microondas (M). MATERIAIS E MÉTODOS: Foram testados seis grupos (n=6/grupo): 1) C + sem polimento (CO); 2) C + polimento químico (CQ); 3) C + banho de água a 75&ordm;C (CW); 4) M + sem polimento (MO); 5) M + polimento químico (MQ); e 6) M + banho de água a 75&ordm;C (MW). A adaptação interna foi avaliada por pesagem em balança analítica de precisão de uma película de silicona de adição interposta entre base de resina e modelo-mestre metálico. A adaptação foi medida imediatamente após o polimento e após 30 dias de armazenamento em água a 37&ordm;C. Os dados foram analisados por ANOVA e teste de Tukey, e por teste t de Student pareado, ao nível de significância de 0,05. RESULTADOS: Não houve diferença significativa na adaptação imediata em função do tipo de polimerização, do polimento ou da interação polimerização/polimento. Após 30 dias, as médias de adaptação (g) foram: CO=2,46 0,32 a; CQ=3,40 &plusmn; 0,23 d; CW=3,14 &plusmn; 0,22 c; MO=3,23 &plusmn; 0,37 c, d; MQ=3,41 &plusmn; 0,47 d; MW=2,81 &plusmn; 0,33 b (médias seguidas por letras diferentes diferem entre si, alfa=0,05). Todos os grupos apresentaram aumento significativo de desadaptação ao longo do tempo, com exceção do grupo CO. CONCLUSÃO: Os resultados sugerem que as bases de resina Veracril® submetidas a polimento químico apresentaram diminuição de adaptação interna em 30 dias, embora a adaptação imediata não tenha sido afetada

Development of an experimental optoelectronic device to study the amplitude of mandibular movements

This study aimed to present a wireless mandibular motion tracking device and optoelectronic data acquisition system developed to analyze the real-time spatial motion of the entire mandible during mouth opening and closing with no restriction of any movement. The procedures were divided into three phases: confection of a kinematic arch, dynamic digital video image acquisition, and image processing and analysis by using graphic computation. Four sequences of jaw opening/closing movements were recorded in lateral view: two from the maximum intercuspation (MIC) and the other two from a forced mandibular retruded position. Jaw motion was recorded by a digital video camera and processed as spatial coordinates corresponding to the position variation of the markers in the kinematic arch. The results showed that the method was capable of recording and processing the dynamics of the mandibular movements during jaw opening/closing using pixel-magnitude points. The mandible showed points with less displacement located near the temporomandibular joint during the opening/closing movements from the mandibular retruded position. When the jaw movements were recorded from MIC, these points were located near the mandibular foramen

A within-subject comparison of short implants in the posterior region: retrospective study of up to 10 years

PURPOSE: This intra-patient retrospective study of up to 10 years evaluated the clinical success and risk factors of 6- and 8-mm long implants and their respective prostheses. MATERIALS AND METHODS: The sample consisted of patients treated at a Military Polyclinic dental service, who received both 6- and 8-mm long tissue level implants in the posterior region of the same arch. Data were collected from the dental charts, clinical and radiographic exams, self-report of sleep bruxism, measurement of maximum occlusal force, and clinical crown-to-implant (C/I) ratio. Data were analyzed by descriptive and inferential statistics with univariate and hierarchical multivariate models, at the 0.05 significance level. RESULTS: The 30 patients (27 women) had 85 implants and 83 prostheses. Two implants were lost before prosthesis installation (implant survival: 97.6%). Ten events of prosthetic complication (screw tightening loss) occurred in five patients (success rate: 87.9%) in a single moment. Only the variable C/I ratio had a significant effect for repairable prosthesis complication (P<.05). CONCLUSION: The results suggest that 6- and 8-mm long implants have similar long-term clinical success for implants and prostheses.info:eu-repo/semantics/publishedVersio

Avaliação funcional da reabilitação oral com prótese parcial removível após cinco anos

Most removable partial denture (RPD) wearers are satisfied with their prostheses, but the factors that influence satisfaction and acceptance are still not determined. OBJECTIVE: This study explored technical, biological, and satisfaction variables for the functioning of RPDs after five years, and compared the evaluation by the patient and by the clinician. MATERIAL AND METHODS: Fifty adults (39 females, 11 males) were re-examined after five years of RPD service. Data were collected through clinical examination and a structured questionnaire to record the conditions of supporting soft tissues, prosthesis acceptance and technical characteristics, mastication, esthetics, comfort, hygiene, and need for professional intervention. Data were analyzed by descriptive statistics and Spearman correlation. RESULTS: More than 50% of patients classified their RPDs as excellent regarding retention, mastication, esthetics, comfort, and hygiene. In the professional evaluation, retention and stability were considered excellent in more than 66% of cases, and hygiene of teeth and prostheses was considered good in 52% and 46%, respectively. The metallic framework and acrylic base were considered adapted in 92% of cases. Prosthesis acceptance was associated with retention, mastication, esthetics, hygiene, and comfort evaluated by the patient, and with retention, stability, and condition of the framework evaluated by the clinician. Retention and mastication/comfort evaluated by the patient had moderate positive correlation with retention and stability measured by the clinician. There was no association of hygiene evaluation by the patient and by the clinician. CONCLUSIONS: After five years, the oral rehabilitation with RPDs was satisfactory for most cases. There was correspondence between retention/retention and mastication-comfort/stability variables evaluated by the patient and by the clinician. Oral and prosthesis hygiene were not related.A maioria dos usuários de PPR mostra-se satisfeita com suas próteses, porém os fatores que influenciam a satisfação e aceitação não estão determinados. OBJETIVO: Este estudo explorou variáveis técnicas, biológicas e de satisfação no funcionamento de próteses parciais removíveis (PPRs) após cinco anos de uso, comparando a avaliação do paciente e do cirurgião-dentista. MATERIAIS E MÉTODOS: Cinqüenta adultos (39 mulheres, 11 homens) foram reexaminados após cinco anos da instalação de PPR. Através de exame clínico e questionário estruturado, foram coletados os dados relativos às condições dos tecidos de suporte, aceitação e características técnicas da PPR, mastigação, estética, conforto, higiene e necessidade de intervenção profissional. Os dados foram analisados por estatística descritiva e por correlação de Spearman. RESULTADOS: Mais de 50% dos pacientes classificaram suas próteses como excelente quanto à retenção, mastigação, estética, conforto e higiene. Na avaliação do profissional, retenção e estabilidade foram consideradas excelentes em mais de 66% dos pacientes, e a higiene dos dentes e da prótese foi considerada boa em 52% e 46% dos casos, respectivamente. As armações metálicas e bases acrílicas foram consideradas adaptadas em 92% dos casos. Aceitação da prótese foi associada com retenção, mastigação, estética, higiene e conforto avaliados pelo paciente, e com retenção, estabilidade e condição da armação metálica avaliadas pelo profissional. Retenção e mastigação/conforto, avaliados pelo paciente, mostraram correlação positiva moderada com retenção e estabilidade medidas pelo profissional. Não houve associação entre avaliação de higiene pelo paciente e pelo profissional. CONCLUSÕES: Após cinco anos, a reabilitação oral com PPR estava satisfatória na maioria dos casos. Houve correspondência entre as variáveis retenção/retenção e mastigação-conforto/estabilidade. Higiene oral e da prótese não mostraram associação