Renata Pilli Jóias

Load-application devices: a comparative strain gauge analysis

In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukeys test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM.

Thickness and marking quality of different occlusal contact registration strips

Objectives Evaluate the thickness and the marking quality of different occlusal contact registration strips (OCRS) and a possible correlation between them. Material and Methods The following OCRS were selected: Accufilm II, BK20, BK21, BK22, BK23, BK28, and BK31. The thickness was measured in three points of the OCRS with an electronic measuring device (TESA), and the mean was calculated. To produce the marks on the strips, composite resin specimens were adapted to a universal testing machine (Versat 2000) with 40 kgf load cell at a speed of 1.0 mm/min. The mark images were photographed with a stereoscopic microscope (Stemi SV11) and processed and analyzed by the 550-Leica Qwin® analyzer. Results Values (μm) found in the 1st and 2nd thickness measurements were: Accufilm II - 16.4 and 14.2; BK20 - 10.0 and 8.1; BK21 - 9.5 and 8.0; BK22 - 9.7 and 8.7; BK23 - 9.8 and 7.9; BK28 - 12.8 and 10.0; and BK31 - 8.4 and 8.0, respectively. The mean (mm2) values found in the mark areas were: Accufilm II - 0.078; BK20 - 0.035; BK21 - 0.045; BK22 - 0.012; BK23 - 0.022; BK28 - 0.024; and BK31 - 0.024. The results were submitted to the Kruskal-Wallis (p<0.05) and Pearson’s correlation tests. Conclusions Only in the 2nd measurement, the OCRS thickness observed was similar to the value indicated by the manufacturers; the Accufilm II and the BK28 strips showed the better marks; and no correlation was found between the thickness and the marking area.

Evaluation of the dental arch asymmetry in natural normal occlusion and Class II malocclusion individuals

Objective: To verify the presence and degree of asymmetry of dental arches in Brazilian individuals with natural normal occlusion and Class II, Divisions 1 and 2 malocclusions. Methods: The study evaluated the symmetry of the maxillary and mandibular dental arches of 180 pairs of dental casts, divided into: Group I = 60 pairs of natural normal occlusion individuals; Group II = 60 pairs of Class II, Division 1 malocclusion individuals; and Group III = 60 pairs of Class II, Division 2 malocclusion individuals. A device was used to measure dental midline deviation and the canine tip in the dental arches (in degrees). It was also verified the distance of the upper canines from the palatal suture, intercanine distance, and anteroposterior upper and lower first molar position. Results: Dental arches of individuals from all groups presented asymmetry, regardless of the presence of malocclusion. Group I showed a lower asymmetry degree in relation to Groups II and III. The asymmetry in Groups II and III was similar. Conclusion: The dental arches of individuals with natural normal occlusion and with Class II, Division 1 and Division 2 malocclusions showed asymmetry. The asymmetry degree was higher in the mandibular dental arches than in the maxillary dental arches in all 3 evaluated groups.

Consequências da falta de colaboração do núcleo familiar no controle da doença cárie. Relato de caso

Introducao: As evidencias cientificas mostram que existe uma correlacao de fatores comportamentais de risco (habitos de higiene bucal, habitos alimentares e uso do fluor) e o desenvolvimento da doenca carie em criancas pre-escolares

General and oral characteristics of Rett syndrome: case report

Introduction: Rett syndrome is a neurodegenerative disease that affects females of all races worldwide. It is the second most frequent cause of mental disability in girls. Objective: To describe the general and oral characteristics at stage three. Case report: A girl aged seven years and seven months, leukoderma, coming from Vallo della Lucania, Salerno, Italy was at the stage three of Rett syndrome. At the first stage, from six to eighteen months of life, the girl ate by herself, but she did not walk. At the second stage, from eighteen months of life, she started the ataxic gait and stopped talking. At the third stage, she had the reduction of the autist behavior, improved the eye contact, smile and communicative abilities. The genetic examination revealed de novo mutation, that is, without inheritance. Conclusion: Rett syndrome lacks specific treatment. Adjuvant therapies include physiotherapy, hydrotherapy, occupational therapy, music therapy, equine therapy, as well as therapies to treat some symptoms. A multidisciplinary treatment is required. The prognosis consists of following-up the individual throughout life, treating the symptoms. Keywords: Autistic Disorder, Chronic disease, Epilepsy, Intellectual Disability, Rett Syndrome.

Cianoacrilato na colagem de Bráquetes ortodônticos em resina acrílica: há maior adesão?

Pacientes em tratamento ortodontico apresentam restauracoes provisorias com frequencia. No entanto, poucos estudos avaliam a influencia dos adesivos na resistencia ao cisalhamento dos braquetes nessas superficies. A resina acrilica e comumente indicada para colagem de braquetes, porem o uso do cianoacrilato como adesivo ortodontico e uma opcao analisada. O objetivo do presente trabalho foi avaliar o desempenho do cianoacrilato associado aos materiais comumente utilizados para a fixacao de braquetes metalicos em restauracoes provisorias de resina acrilica. Quarenta amostras em resina acrilica foram preparadas e as superficies homogeinizadas com lixas de carboneto de silicio (320 e 600). Em seguida, as amostras foram divididas aleatoriamente em quatro grupos (n=10) com base no tratamento de superficie e agente de uniao: G1 - braquetes colados com resina acrilica; G2 - braquetes colados com resina acrilica e aplicacao de cianoacrilato; G3 - braquetes colados com Transbond(tm) XT; G4 - braquetes colados com Transbond(tm) XT e aplicacao de cianoacrilato. Foram utilizados braquetes ortodonticos de aco inoxidavel, prescricao Roth, Kirium (3M/Abzil) para incisivos centrais superiores direitos, slot 022. Apos colagem, as amostras foram submetidas ao teste de cisalhamento a uma velocidade de 0,5mm/min em uma maquina de ensaios universal (EMIC DL-1000). Os dados foram coletados e submetidos a analise estatistica pelo teste ANOVA com nivel de significância de 5%. A associacao de resina acrilica ao cianoacrilato (G2) resultou na maior resistencia ao cisalhamento (13,76 MPa), mas nao significativa em comparacao aos valores obtidos para a resina acrilica (G1= 7,76 MPa). O mesmo pode ser observado para a associacao Transbond(tm) XT e cianoacrilato (G4= 4,03 MPa) em relacao a utilizacao da Transbond(tm) XT de forma isolada (G3= 3,87 MPa) e resina acrilica. O tratamento de superficie tem efeito significativo na resistencia da uniao dos braquetes colados aos materiais provisorios. A associacao de cianoacrilato ao monomero de metilmetacrilato apresentou maior resistencia ao cisalhamento, sendo mais indicada clinicamente.

Influence of dental chair backrest inclination on the registration of the mandibular position.

STATEMENT OF PROBLEM Varying the inclination of the dental chair backrest might alter the distribution of occlusal contact points. PURPOSE The purpose of this study was to identify the influence of backrest inclination on the registration of the mandibular position. MATERIAL AND METHODS Ten participants aged between 18 and 30 years with a complete permanent dentition, uncompromised motor function, no tooth mobility, and no temporomandibular disorders were selected. To register interocclusal contacts, an autopolymerizing methylmethacrylate device was adapted to the maxillary anterior teeth and a composite resin increment was added to the mandibular central incisors. Contacts were registered with the following variations in the inclination of the dental chair backrest: 90 degrees, 120 degrees, and 180 degrees. A standardized digital photograph was made of each mark in each backrest position, and the images were superimposed to measure the distances in registration from 90 to 120 and from 90 to 180 degrees. Data were analyzed with the Student paired t test (α=.05). RESULTS When the chair was inclined from the 90-degree to the 120-degree position, the mandible was repositioned posteriorly by a mean of 0.67 mm, but the difference was not statistically significant. When the chair was inclined from the 90-degree to the 180-degree position, however, the mandible was repositioned posteriorly by a statistically significant mean of 1.41 mm. CONCLUSIONS Mandibular position is influenced by increasing inclination, and this influence was statistically significant at a 180-degree incline.

Evaluation of changes in clinical crown length of lower anterior teeth after treatment with Frankel-2's appliance.

PURPOSE The aim of this study was to test the null hypothesis that there is no change in the lower anterior teeths crown size when measured just after the treatment with Frankel-2s orthopedic appliance and in a long-term posttreatment follow-up. MATERIALS AND METHODS The sample was composed of 34 plaster models belonging to 9 male and 8 female individuals, treated at the College of Health, Methodist University of São Paulo, São Bernardo do Campo, São Paulo, Brazil, with mean age of 12 years and 6 months (standard deviation [SD] =7 months) at T1 (end of the treatment with Frankel-2s function regulator), and 19 years and 8 months (SD = 7 months) at T2 (7.11 years after the end of the treatment). RESULTS The distance from the incisal edge to the most concave portion of the gingival margin of the lower incisors and canines was measured using a digital caliper. Data analysis was carried out by means of Students t-test and paired-t test. Among the lower anterior teeth, the teeth 31, 33, 42 and 43 showed a statistically significant increase in their crown length, whereas the teeth 32 and 41 showed no changes. CONCLUSION It can be concluded that there is a tendency to increase the clinical crown of lower anterior teeth throughout the years after the mandibular advancement treatment by using functional devices, rejecting the null hypotheisis.

Evaluation of the Cervical Vertebrae Maturation Index in Lateral Cephalograms Taken in Different Head Positions

The aim of this study was to evaluate if upward or downward head inclination might interfere with determination of the growth stage, using cervical vertebrae maturation index (CVMI), in order to verify the accuracy of such diagnosis when radiographs are taken with errors. Forty-nine patients, 26 females and 23 males, aged 9 to 15 years, were submitted to 3 lateral cephalograms: normal (NHP), with 15° upward head inclination (NHP-Up), and with 15° downward head inclination (NHP-Down). Three examiners evaluated the CVMI on the 147 cephalograms. The agreement among examiners was higher in the evaluation of cephalograms taken in NHP. The weighted Kappa test revealed moderate to substantial agreement between NHP and NHP-Up and between NHP and NHP-Down. There was greater agreement between NHP-Up and NHP-Down. It may be concluded that the evaluation of the CVMI on cephalograms in NHP is different as compared with radiographs taken with inclinations. Both NHP-Up and NHP-Down exhibited greater disagreement in the interpretation among examiners, since the evaluation method was not designed for cephalograms with positioning errors.