Artemio Luiz Zanetti

Analysis of the condyle/fossa relationship before and after prosthetic rehabilitation with maxillary complete denture and mandibular removable partial denture

STATEMENT OF PROBLEM The influence of the loss of posterior teeth on the condylar position and on temporomandibular disorders (TMDs) remains a controversial issue. PURPOSE This study investigated whether prosthetic rehabilitation promoted modification of the condylar position in subjects without symptoms of TMDs. MATERIAL AND METHODS The temporomandibular joints (TMJs) of 12 women (age 37 to 74), all with existing maxillary complete dentures but no removable partial denture (RPD) restoring the Kennedy class I partially edentulous mandibular arch and no clinical signs of TMDs according to the criteria established by Helkimo, were viewed in maximal intercuspal position with corrected lateral tomography before and after prosthetic rehabilitation with a new maxillary complete denture and a mandibular RPD. Before prosthetic rehabilitation, a mandibular stabilizing base was fabricated to prevent the existing maxillary complete denture from dislodging during tomographic examination. Two methods were used to evaluate tomograms: (1) linear measurements of the subjective narrowest anterior and posterior intra-articular joint spaces made from the tomograms by use of a digital caliper and (2) linear measurements of the anterior and posterior intra-articular joint spaces on the basis of drawings and tracings. Repeated-measures analysis of variance followed by orthogonal contrasts were used to evaluate differences between measurements carried out on the same subject under the different test conditions of the study (before prosthetic rehabilitation, before prosthetic rehabilitation with a mandibular stabilizing base in position, and after prosthetic rehabilitation) (P<.05). RESULTS Before prosthetic rehabilitation, a predominance of posterior condylar positions was observed. Before prosthetic rehabilitation with a mandibular stabilizing base in position, a significant decrease was observed in posterior condylar positions (P=.03). This decrease was more marked after prosthetic rehabilitation (P=.02). The subjective evaluation and comparison on the basis of drawings and tracings used to analyze the tomograms produced similar results (P=.70). CONCLUSION Within the limitations of this study, significant changes in the condylar position occurred after prosthetic rehabilitation in subjects without symptoms of TMDs.

Thickness of the remaining enamel after the preparation of cingulum rest seats on maxillary canines

PURPOSE This study evaluated the level of tissue removal that takes place on enamel and dentin during cingulum rest seat preparation. MATERIAL AND METHODS A quantitative evaluation of the thickness of the remaining enamel of cingulum seat preparations to receive removable partial denture rests was carried out in 20 maxillary canines with a light optical microscope. RESULTS Thirty percent of the preparations were overextended into dentinal tissue, and 85% had depths that were insufficient to receive rests.

A new method to simplify and increase the precision of maxillary cast mounting procedures in fully adjustable or semiadjustable articulators

This study introduces a new impression procedure that permits mounting the maxillary stone cast in an articulator for any patient treatment and is applicable to any dental arch with any impression material. A transfer tray was designed that makes it possible to transfer the patients maxillary impression to the articulator in a one-stage procedure without the need for making record bases and occlusion rims or the need to use a face-bow bite fork.

Dimensional Accuracy of Stone Casts Obtained with Multiple Pours into the Same Mold

Aim. The aim of the present study was to compare the dimensional accuracy of stone casts obtained with vinyl polysiloxane molds through the double-impression technique with three pours into the same mold. Methods. A stainless steel master model was constructed simulating a three-unit fixed prosthesis. Twelve impressions were taken of this master model with addition silicone, using the double-impression technique. Three pours of type IV gypsum were then made into each mold, thus producing 36 casts. The pours were made 1 hour, 6 hours and 24 hours after the impression procedure. Next, intra- and interabutment measurements were made in a coordinate measuring machine. Results. Comparative analysis of the dimensional accuracy of stone casts resulting from multiple pours was not statistically significant in pours first and second (P > 0.05). These values, however, were statistically significant at third pour in the height in abutment 1 and upper distance interabutment. Conclusion. The wait time (1 hour, and 6 hours) observed before pouring the stone into the same molds did not cause significant dimensional accuracy of the casts.

Analysis of the prevalence of different topographical characteristics of the residual ridge in mandibular free-end arches

This study observed the prevalence of different types of residual ridge inclination in free-ends of mandibles and reported possible correlative factors that may affect resorption. For this purpose, periapical radiographs and individual data collected from a sample of 64 hemiarches were used. Two radiographs were taken of each free-end, and tracing was employed to determine the angles formed by the resorption configuration in the area of the 1st mandibular molar. The following conclusions were drawn: 1). the great majority of alveolar ridges were distally descending; 2). the average angle was wider for users of mandibular removable partial dentures; 3). the results obtained suggest that the type of opposing maxillary arch affects the inclination of mandibular ridges; 4). greater inclination was observed when the 2nd bicuspids of the mandible were the abutment teeth; 5). no significant correlation was established between age, sex and residual ridge resorption.

Estudo da viabilidade do preparo direto para descanso de cíngulo em incisivo central superior

The present research evaluated the viability of the direct preparation of lingual rest seats in maxillary central incisors. Ten completely sound specimens were embedded in acrylic resin supports and distributed among five specialists who prepared the rest seats. The coronary portion of the teeth was then cut using a previously made incisal index as guide. The preparation was characterized by angular and linear measurements that enabled a comparative analysis between the original outline of the tooth and its respective prepared model, while permitting the determination of dentinal exposure. The observations were undertaken in digitized images of these outlines utilizing a specific computer program. From the fifty models prepared under well-established criteria, thirty-three showed perforation of the enamel. Conclusively, the maxillary central incisor may not be indicated to receive a directly prepared lingual rest seat.