An evaluation of the relationship between clinical requirements and tests of competence in a competency-based curriculum in dentistry.

BACKGROUND: The development of competencies in dentistry is a complicated process that calls for the development of not just cognitive and psychomotor abilities but also behaviors and attitudes that change as technical proficiency increases and meaningful patient encounters occur. This study examined the relationship between the number of clinical requirements completed by dental students and subsequent performance on tests of competence. The null hypothesis stated there would be no significant linear relationship different from zero between absolute clinical requirements and grades attained in various tests of clinical competence. METHODS: Retrospective assessment data for 81 students were used in this analysis. Data included the amounts of clinical requirements completed for operative dentistry, endodontics, periodontics, and fixed prosthodontics together with data on the respective performance in tests of competence. Correlation was ascertained between grades for tests of competence and the corresponding clinical requirements using a non-parametric Spearman's Rho test at an alpha level of 0.05. RESULTS: Fixed prosthodontics and posterior endodontics were the least common procedures completed by dental students. Statistically significant weak correlations were found between the amounts of clinical requirements performed for posterior endodontic(p = 0.005) and operative procedures (p = 0.006) and associated performance in tests of competence. A moderate correlation was found between the number of fixed prosthodontic procedures completed and associated performance in tests of competence. This latter correlation, however, was not statistically significant (p = 0.654). A significant weak correlation was found between requirements completed for periodontics and the associated test of competence (p = 0.04). A highly statistically significant moderate correlation was found between clinical requirements for anterior endodontics and the associated performance in the tests of competence (p < 0.001). CONCLUSION: The null hypothesis was rejected since a positive correlation was found between the absolute clinical requirements completed and grades in tests of competence. However, only a weak to moderate degree of correlation was found between the completion of clinical requirements and performance in tests of competence for common clinical procedures that new dental graduates should be able to perform.

Radiographic evaluation of the technical quality of root canal fillings performed by dental students

The objective of this study was to evaluate radiographically the technical quality of root canal fillings performed by dental students at the School of Dentistry, University of the West Indies. The school's database between 2000 and 2004 was investigated for patients with completed root canal treatment. The final sample consisted of 198 patients with 288 root-filled teeth and 460 canals. The length, presence of voids, taper, curvature of canal and fractured instruments were recorded and scored. Chi-squared analysis was used to determine statistically significant differences between the technical quality of root fillings and tooth type. Sixty-three per cent, 27.6% and 72.2% of root-filled canals had adequate length, density and taper respectively. The overall acceptability of root fillings having adequate length and taper, absence of voids and no fractured instruments was found in 10.9% of canals. Changes in teaching methods may be required to improve the technical quality of root canal treatment done by dental students.

Radiographic evaluation of the technical quality of root canal fillings performed by dental students.

The objective of this study was to evaluate radiographically the technical quality of root canal fillings performed by dental students at the School of Dentistry, University of the West Indies. The school's database between 2000 and 2004 was investigated for patients with completed root canal treatment. The final sample consisted of 198 patients with 288 root-filled teeth and 460 canals. The length, presence of voids, taper, curvature of canal and fractured instruments were recorded and scored. Chi-squared analysis was used to determine statistically significant differences between the technical quality of root fillings and tooth type. Sixty-three per cent, 27.6% and 72.2% of root-filled canals had adequate length, density and taper respectively. The overall acceptability of root fillings having adequate length and taper, absence of voids and no fractured instruments was found in 10.9% of canals. Changes in teaching methods may be required to improve the technical quality of root canal treatment done by dental students.

Comparison of the mechanical properties of two nano-filled composite materials / Comparação das propriedades mecânicas de dois materiais nanocompósitos

OBJETIVO: A finalidade deste estudo foi quantificar e comparar as propriedades mecanicas de dois materiais restauradores nanocompositos disponiveis comercialmente. MATERIAL E METODO: Especimes de dois nanocompositos, Z350TM e GrandioTM, foram polimerizados com luz LED por 30 segundos e submetidos a testes mecanicos. As propriedades testadas incluiram: resistencia flexural, resistencia tensil diametral, resistencia a fratura e microdureza (topo e fundo). RESULTADOS: O Grandio apresentou valores de resistencia flexural media maiores quando comparados com o Z350 (89.1 MPa vs 61.9 MPa). O Grandio demonstrou maior microdureza das superficies de topo de cada composito quando comparada com sua correspondente superficie de fundo. As propriedades de resistencia a fratura e forca tensil diametral nao foram fatores discerniveis neste estudo em particular. CONCLUSAO: Grandio possui maiores valores para propriedade de resistencia flexural e dureza quando comparado com o Z350. Nao houve diferencas entre os dois materiais em relacao a resistencia a fraturas e resistencia a forcas tenseis diametrais.

OBJECTIVE: The purpose of this study was to quantify and compare the mechanical properties of two commercially available nanocomposite restorative materials. MATERIAL AND METHODS: Specimens of two nanocomposites, Z350TM and GrandioTM, were polymerized with a LED light for 20 seconds and subjected to mechanical tests. Properties tested included: flexural strength, diametral tensile strength, fracture toughness and microhardness (top and bottom). RESULTS: Grandio exhibited significantly higher mean flexural strength values when compared to Z350 (89.1 MPa vs 61.9 MPa). Grandio exhibited significantly higher top microhardness values when compared to Z350. Additionally when microhardness for the top surfaces of each composite were compared with their corresponding bottom surfaces, the bottom surfaces demonstrated significantly lower readings. The properties of fracture toughness and diametral tensile strength were non-discerning factors in this particular study. CONCLUSION: Grandio has greater observed values for the properties of flexural strength and hardness when compared with Z350. There was no difference between the two materials with respect to their fracture toughness and diametral tensile strength.

Cusp fracture resistance of maxillary premolars restored with the bonded amalgam technique using various luting agents.

Objective. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. Materials. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem mu (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. Results. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. Conclusion. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone.

Cusp fracture resistance of maxillary premolars restored with the bonded amalgam technique using various luting agents

OBJECTIVE. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. MATERIALS. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem ì (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. RESULTS. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. CONCLUSION. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone.

Comparison of the Mechanical Properties of two Nano-filled Composite Materials

OBJECTIVE: The purpose of this study was to quantify and compare the mechanical properties of two commercially available nanocomposite restorative materials. MATERIAL ANDMETHODS: Specimens of two nanocomposites, Z350TM and GrandioTM, were polymerized with a LED light for 20 seconds and subjected to mechanical tests. Properties tested included: flexural strength, diametral tensile strength, fracture toughness and microhardness (top and bottom). RESULTS: Grandio exhibited significantly higher mean flexural strength values when compared to Z350 (89.1 MPa vs 61.9 MPa). Grandio exhibited significantly higher top microhardness values when compared to Z350. Additionally when microhardness for the top surfaces of each composite were compared with their corresponding bottom surfaces, the bottom surfaces demonstrated significantly lower readings. The properties of fracture toughness and diametral tensile strength were non-discerning factors in this particular study. CONCLUSION: Grandio has greater observed values for the properties of flexural strength and hardness when compared with Z350. There was no difference between the two materials with respect to their fracture toughness and diametral tensile strength.

Cusp fracture resistance of maxillary premolars restored with the bonded amalgam technique using various luting agents.

Objective. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. Materials. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem æ (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. Results. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. Conclusion. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone.

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements

Este estudo avaliou a retenção de pinos intra-radiculares cerâmicos à base de zircônia (CosmoPost system) fixados com cimento de ionômero de vidro ou resinoso. Trinta e dois dentes extraídos, livres de cárie e não-restaurados foram selecionados e armazenados em solução de clorexidina e água. Os dentes foram submetidos a tratamento endodôntico e distribuídos aleatoriamente em dois grupos (n=16). Cada dente teve a coroa removida e um espaço protético de 1.0 mm de profundidade (medida a partir da superfície radicular) foi preparado para receber um pino de dióxido de zircônio com 1,4 mm de diâmetro. Cada grupo teve os pinos fixados com cimento de ionômero de vidro (Fuji I) ou cimento resinoso (Variolink II). Os conjuntos dente/pino foram incluídos em blocos de resina e submetidos a testes de tração. Foi utilizado um tensiômetro para registrar a força de tração necessária para deslocar os pinos cimentados. Os valores médios de tração de ambos os grupos foram analisados por ANOVA e pelo teste t de Student. O nível de significância foi fixado em 5%. Foram obtidos os seguintes valores médios de tensão de ruptura (N) e desvios-padrão: Fuji I = 121,8 (±17,4); Variolink II = 228,1 (±36,8). Os pinos fixados com cimento resinoso apresentaram maior resistência ao deslocamento do que aqueles fixados com cimento de ionômero de vidro, sendo esta diferença estatisticamente significante (p<0,05). Pode-se concluir que os pinos de zircônia cimentados com cimento resinoso (Variolink II) apresentaram falhas sob valores de tensão significativamente maiores que os registrados para os pinos cimentados com ionômero de vidro (Fuji I). Independente do tipo de cimento utilizado, os pinos apresentaram falhas adesivas na interface cimento/pino ao serem submetidos a esforços de tensão.

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirty two extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surfaceto receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student’s t-test. Significance level was set at 5 percent. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (plus or minus 17.4) and Variolink II = 228.1 (plus or minus 36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher valuescompared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements.

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirty-two extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surface to receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student's t-test. Significance level was set at 5%. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (+/-17.4) and Variolink II = 228.1 (+/-36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher values compared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.