Bruna Aguiar do Amaral

Immunohistochemical expression of E-cadherin and β-catenin in ameloblastomas and tooth germs

OBJECTIVE The aim was to analyze the expression of E-cadherin and beta-catenin in ameloblastomas and tooth germs to determine their roles in cell differentiation processes and invasiveness compared with odontogenesis. STUDY DESIGN Twenty-one ameloblastoma cases (16 solid and 5 unicystic tumors) and 5 tooth germs were submitted to the immunohistochemical detection of E-cadherin and beta-catenin. Immunoreactivity was evaluated using descriptive and semiquantitative analysis, investigating the location and intensity of staining. The Fisher exact test was performed, and P values of <.05 were considered to indicate statistical significance. RESULTS There was no statistically significant difference in the expression of E-cadherin and beta-catenin between solid and unicystic ameloblastomas (P = .59; P = .63; respectively). The same was found when comparing solid and unicystic ameloblastomas with the tooth germs for both E-cadherin (P = .53; P = .44; respectively) and beta-catenin (P = .12; P = .16; respectively). Nuclear staining of beta-catenin was observed in only 4 cases (3 solid and 1 unicystic tumor). CONCLUSION The results showed no differences in the expression of E-cadherin or beta-catenin between tooth germs and solid and unicystic ameloblastomas. The expression of these molecules seems mainly to be related to the process of cell differentiation.

Effect of acetyl resin retentive arms on the retentive force of circumferential clasps: An in vitro study

PURPOSE To compare and to evaluate the stability of the retentive force of cobalt-chromium (Co-Cr) circumferential clasps (control) to those with an acetyl resin retentive arm. METHODS Sixteen specimens with a couple of circumferential clasps were made using Co-Cr over a metal model providing 0.25 mm undercuts. Eight specimens were fabricated without the anterior retentive arm, which was made later using acetyl resin (Dental D). Insertion and removal simulation test was performed through 7250 cycles. The retentive force was recorded in Newtons (N) for periods corresponding to 0, 1, 2, 3, 4, and 5 years. The data were subjected to ANOVA and Tukey test to compare periods and to Students t test to compare groups (α=0.05). RESULTS Mean (SD) is presented for Co-Cr and resin groups, respectively: 8.09(3.05) and 2.79(1.57) in period 0; 10.48(4.25) and 3.32(1.92) in 1 year; 10.09(4.15) and 3.47(1.81) in 2 years; 9.87(4.30) and 3.46(1.87) in 3 years; 9.46(3.93) and 3.27(1.59) in 4 years; 9.63(3.79) and 3.41(1.59) in 5 years. There were significant differences for Co-Cr between periods of 0 and 1 (p<0.001), 0 and 2 (p<0.01) and 0 and 3 (p<0.05). In the resin group, no significant differences were found between periods (p>0.05). Comparisons between the groups showed statistical differences for all tested periods: 0 (p=0.0012), 1 (p=0.0013), 2 (p=0.0019), 3 (p=0.0031), 4 (p=0.0027) and 5 years (p=0.0014). CONCLUSIONS Acetyl resin retentive arms, even if only in the anterior clasps, can significantly reduce the retentive force, but this force remained stable after 5 years of simulated use.

Estudo Clínico Longitudinal Comparativo da Condição Periodontal de Pilares Diretos de Próteses Parciais Removíveis Dento-Suportada e Dento-Muco-Suportada

Objetivo: Realizar uma avaliacao clinica longitudinal do periodonto de pacientes usuarios de protese parcial removivel (PPR), comparando os pilares diretos de PPR dento-suportada com os de PPR dento-muco-suportada. Metodo: Participaram da pesquisa 50 pacientes, com media de idade de 45 anos. Estes foram examinados no momento da instalacao da protese e apos 3, 6, 9 e 12 meses, por um unico examinador. Em cada exame foram verificados: recessao gengival (RG), profundidade de sondagem (PS), indice de placa (IP), indice gengival (IG) e quantidade de mucosa ceratinizada (MC).Todos os pacientes receberam orientacao de higiene oral, acompanhada de profilaxia e, quando necessario, foi realizada raspagem e alisamento corono-radicular. Para avaliar os desfechos com relacao ao tipo de protese no grupo pilar direto, foi feita analise a partir do intervalo de confianca. Resultados: A protese dento-muco-suportada mostrou valores significativamente superiores de RG, IG e IP, enquanto significativamente inferiores de MC. Ao longo do tempo, os dois tipos de protese nao apresentaram diferencas significativas do exame inicial para o final para as variaveis RG, PS, MC e IG, enquanto o IP foi significativo somente na protese dento-suportada. Conclusao: Os elementos pilares adjacentes a extremidades livres apresentaram condicao periodontal menos favoravel do que os pilares adjacentes a espacos intercalados, porem o uso de PPR nao agravou a condicao inicial, apos um periodo de acompanhamento de 12 meses. Indicando que em um ano nao se observa grandes diferencas entre os pilares diretos das proteses dento-suportadas e dento-muco-suportadas, o que sugere um acompanhamento profissional por um periodo mais prolongado.