In Vitro Assessment of Retention and Resistance Failure Loads of Teeth Restored with a Complete Coverage Restoration and Different Core Materials.

PURPOSE: To investigate in vitro the retention and the resistance form, as well as the failure modes of maxillary premolars restored with cast metal crowns and different core materials. MATERIALS AND METHODS: Sixty human extracted maxillary premolars were selected according to their size and were embedded in PMMA resin blocks. After removing a part of their clinical crowns, the teeth were randomly divided into 3 groups of 20 teeth and were either left unrestored, or they were restored with amalgam or composite resin. All teeth were prepared for a cast metal complete coverage restoration. The restorations were cemented on the prepared teeth with a resin-modified glass ionomer luting agent (GC Fuji Plus). All specimens were subjected to static loading at 1 mm/min by a universal testing machine, until failure. Half the specimens of each group were subjected to tensile loading along the long axis of the teeth. The other half were subjected to compressive loading at a 30° angle. Failure loads and failure modes for each tooth were recorded. The statistical analysis included descriptive statistics, one-way ANOVA, and Tukey's HSD test. RESULTS: One-way ANOVA revealed statistically significant differences among the 3 tested groups (p < 0.05) for both tests. The group of teeth with no core material presented the highest failure loads for both the tensile and the compressive loading tests, with mean loads of 381.02 Ν and 741.21 Ν, respectively. Mean tensile and compressive failure loads for the amalgam group were 277.34 Ν and 584.75 Ν, while the composite resin group presented the lowest tensile and compressive failure values, which were 250.77 Ν and 465.78 Ν, respectively. The compression loading test resulted in the same failure mode for all specimens, which included unfavorable fracture of the teeth in combination with detachment of the cast metal complete coverage restorations. The tensile loading test resulted in different failure modes between the groups that used a core material and the group with no core material. CONCLUSIONS: Teeth that lost more than half of their coronal structure presented better retention and resistance form if no core material was used, provided that a minimum of 2-mm axial wall height was present at the missing part. Teeth that have lost more than half of their coronal structure and were restored with amalgam core presented better retention and resistance form than those restored with composite resin. Catastrophic fractures, extending to the root, were associated with compression forces but not with tensile forces.

Restauración post-endodoncia y condición social como factor de preservación dentaria: parte 2 / Post-endodontic restoration and social condition asa factor of tooth preservation. Part 2

El objetivo de este estudio fue conocer el estado dental de piezas endodonciadas en correlación conlas variables de restauración coronaria, estado periodontal, nivel de estudio, condición laboral y acceso a servicios odontológicos. Para ello, se analizó una población de individuos compuesta por sujetos concurrentes a los cursos de posgrado de Endodoncia, del Círculo Odontológico de Córdoba, y al servicio de la Cátedra “B” de Endodoncia de la Facultad de Odontología, Universidad Nacional de Córdoba. Se hicieron tratamientos controlados durante dieciocho meses. La muestra total la conformaron 144 pacientes y se trataron 174 casos. El estudio mostró 37 casos con restauración coronaria definitiva sin fracturas, 52 dientes sin restauración, 21 con fracturas y 1 se perdió. De los dientes restaurados, el55,6 por ciento mostraron periodonto normal; 22,2 por ciento gingivitis, y 22 por ciento periodontitis leve. De los dientes sin restauración, el 3,9 por ciento mostraron periodonto normal; 7,8 por ciento gingivitis; 31,4 por ciento periodontitis leve; 35,3 por ciento periodontitis grave y 21,6 por ciento periodontitis complicada. De los dientes fracturados, el 16,7 por ciento mostraron periodonto normal o gingivitis; 35,3 por ciento periodontitis leve y grave, y un 72,7 por ciento periodontitis complicada. No se demostró asociación entre nivel de estudios, condición laboral y tipo de atención con fracturas de los pacientes, pero los porcentajes sugieren más probabilidad de sufrir fractura en los pacientes de la asistencia pública. El elevado porcentaje de inasistencia a control motivó un análisis específico, del cual se pudo concluir que cuanto más grave la patología periodontal, mayor el porcentaje de inasistencia. El estudio permitió observar desigualdad en el acceso a los servicios odontológicos, dientes no rehabilitados y con compromiso periodontal.

The aim of this study was to know the dental state of endodontic pieces in correlation with different variables such as coronary restoration, periodontic condition, level of study, employment status and access to dental services. A population composed of patients treated in two different postgraduate courses at the Círculo Odontológico de Córdoba and Chair “B” of Endodontics, Faculty of Dentistry,National University of Córdoba were analyzed. Treatments were clinically and radiographicallycontrolled for eighteen months. The total sample included 144 patients and 174 treatments. The studyshowed 37 cases with definitive coronary restoration without fractures, 52 teeth without restoration,21 with fractures, and 1 was lost. From restored teeth, 55.6% showed normal periodontium, 22.2%gingivitis, and 22% mild periodontitis. From teeth without restoration, 3.9% showed normalperiodontitis, 7.8% gingivitis, 31.4% mild periodontitis, 35.3% severe periodontitis and 21.6%complicated periodontitis. From fractured teeth, 16.7% showed normal periodontitis or gingivitis, 35.3% had mild and severe periodontitis, and 72.7% had complicated periodontitis. There has beenno correlation between level of education, work status, and kind of service on patient with fractures,but the percentage suggest that patients in public assistance are more likely to suffer fracture. The highpercentage of non-attendance to control led to a specific analysis, from which it is possible to concludedthat the more severe the periodontal disease, the greater the percentage of non-attendance. The study showed inequality in access to dental services, un rehabilitated teeth and with periodontal compromise.

Posts--when it all goes wrong! Part 1: case assessment and management options.

UNLABELLED: Posts have been used for many years to retain restorations or cores for extra-coronal restorations in endodontically treated teeth.This article discusses the variety of post systems that are available and the incidence and reasons for failure of teeth that have been restored with posts. The treatment options available for the management of such failures are considered, in addition to the indications for both non-surgical and surgical management of endodontic failures. The attitudes of dentists and the perceived complications of attempting post removal are reviewed, along with the evidence to support the prevalence of complications. CLINICAL RELEVANCE: Failure of post-retained restorations is a relatively frequent finding due to failure of the restoration itself or the endodontic treatment. It is therefore important to understand and be aware of the various treatment options available, their indications and associated risks.

Assessment of awareness amongst school teachers regarding prevention and emergency management of dentoalveolar traumatic injuries in school children in Pune City, before and 3 months after dental educational program.

Children have boundless energy, so, they are continuously engaged in some or the other physical activity. It is seen that when child reaches school age, accidents in the school environment in the form of falls, injuries due to contact sports, fights, abuse, etc. are very common and the main cause of traumatic dental injuries. Trauma may vary from minor enamel chipping or avulsion to extensive maxillofacial damage, more serious neck and brain injury, which may cause pain, disfigurement and mental agony, having immediate and long lasting effects. In such cases, a school teacher is in the right position to handle such an emergency and refer the child to the concerned dental surgeon or a pedodontist for further needful care. The main reason for delayed treatment of dental trauma is that people present at the site of injury are unaware of protocol of rapid and appropriate management leading to improper first aid treatment. The purpose of this study was to investigate the awareness of a group of school teachers from different schools about the prevention and emergency management of dental trauma in school children, by means of a questionnaire. Then educating them and reassessing their knowledge after a period of 3 months. Unfortunately, the public is unaware of the risks and does not have enough information about first aid emergency treatment or to avoid traumatic injuries.

Dynamometric assessment of the mechanical resistance of porcelain veneers related to tooth preparation: a comparison between two techniques.

STATEMENT OF PROBLEM: There is little agreement regarding a palatal extension of the preparation for porcelain veneers, as it represents a more invasive technique than a preparation limited to the facial surface of a tooth. PURPOSE: The purpose of this study was to detect the stress in maxillary anterior teeth restored with porcelain veneers and compare the resistance to fracture of porcelain veneers prepared using different preparation designs. MATERIAL AND METHODS: Forty-five maxillary anterior teeth were restored with porcelain veneers and divided into 9 groups as follows: Ca, canines with no preparation; Ca-Ch, canines with palatal chamfer preparation; Ca-W, canines with window preparation; LI, lateral incisors with no preparation; LI-Ch, lateral incisors with palatal chamfer preparation; LI-W, lateral incisors with window preparation; CI, central incisors with no preparation; CI-Ch, central incisors with palatal chamfer preparation; CI-W, central incisors with window preparation. Shear-flexural fracture tests were performed. The fractured specimens were subjected to scanning electron microscope (SEM) analysis. Data were statistically analyzed with univariate analysis of variance and the Tukey post hoc test for multiple comparisons (alpha=.05). RESULTS: The following mean fracture load values (N) were recorded: Ca, 395 +/- 6; Ca-Ch, 310 +/- 8; Ca-W, 322 +/- 8; LI, 309 +/- 8; LI-Ch, 242 +/- 6; LI-W, 225 +/- 8; CI, 298 +/- 8; CI-Ch, 255 +/- 8; CI-W, 221 +/- 6. The SEM analysis showed that both adhesive and cohesive fractures were primarily concentrated at the cervical region. Statistical analysis showed that both the type of tooth and the design of the preparation significantly influenced the resistance to fracture of the restored teeth (P<.001). CONCLUSION: The chamfer preparation is recommended for central incisors, whereas the window preparation showed better results for canines. Both preparations can be adopted in the restoration of lateral incisors.

Reinforcement of weakened cusps by adhesive restorative materials: an in-vitro study.

Pairs of extracted premolar teeth were prepared with MOD cavities reducing the lingual cusp at its base to one of five widths: 1.25-2.25 mm. One of each pair was then restored with one of five adhesive restorative techniques and the weakened cusp of both teeth fractured by a force applied to the cusp at an angle of 30 degrees to the long axis of the tooth. At all cusp widths a layered restorative technique in which the cavities were filled to the enamel-dentine junction with glass-ionomer cement and the enamel replaced by composite, reinforced the weakened cusp more than the other restorative materials tested. This combination of materials to reinforce weakened cusps is worth considering as a cost effective alternative to removing the cusp entirely and making a crown or protecting the cusp with a cuspal coverage gold inlay.