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.

The Cleaning and Whitening Ability of Charcoal Containing Toothpastes and Homeopathic Remedies on Human Tooth Enamel

ABSTRACT: The purpose of this research was to determine the cleaning and whitening ability of two charcoal containing toothpastes compared with baking soda, activated charcoal and a hydrogen peroxide containing whitening toothpaste. Tea-stained enamel/dentin slices were mounted dentin side down in cylinders of auto-polymerizing acrylic and subjected to simulated brushin g. Total color, ΔE, and stained area were measured using a reflectance spectrophotometer and ImageJ software using a Hue, Chroma, and Brightness color threshold method; respectively, at prescribed brushing intervals of baseline, months 1, 6 and 12. A two- w ay repeated measure analysis of variance was performed, with included factors being toothpaste group and time. Statistical analys is revealed the included factor of brushing time interval was significant (p<0.05) for both ΔE and stained area. There was significant interaction for both main effects (p<0.05) for the dependent variable of stained area alone. Significant reduction in ΔE values occurred in all groups except Optic White at the 1-month interval. Statistically significant reduction in stained area occurred at 1-mon th for the baking soda group only. Post-hoc Tukey HSD tests revealed there was significant group*time interaction for baking soda at month 1 for the variable stained area. The charcoal containing (Crest 3D with Charcoal and Colgate Essentials) and non-charcoal contai ning toothpastes (Optic White) only produced a significant stain removal at the 6-month interval.

RESUMEN: El propósito de esta investigación fue determinar la capacidad de limpieza y blanqueamiento de dos pastas dentales que contienen carbón en comparación con bicarbonato de sodio, carbón activado y una pasta dental blanqueadora que contiene peróxido de hidrógeno. Los cortes de esmalte/dentina teñidos con té se montaron con el lado de la dentina hacia abajo, en cilindros de acrílico autopolimerizable y se sometieron a un cepillado simulado. El color total, ΔE y el área teñida se midieron usando un espectrofotómetro de reflectancia y el software ImageJ usando un método de umbral de color de tono, croma y brillo; respectivamente, en los intervalos de cepillado prescritos al inicio, los meses 1, 6 y 12. Se realizó un análisis de varianza de medidas repetidas de dos vías, con factores incluidos como el grupo de pasta de dientes y el tiempo. El análisis estadístico reveló que el factor incluido del intervalo de tiempo de cepillado fue significativo (p<0,05) tanto para ΔE como para el área manchada. Hubo interacción significativa para ambos efectos principales (p<0,05) para la variable dependiente del área teñida sola. Se produjo una reducción significativa en los valores de ΔE en todos los grupos excepto Optic White en el intervalo de 1 mes. Se produjo una reducción estadísticamente significativa en el área manchada al mes solo para el grupo de bicarbonato de sodio. Las pruebas post-hoc Tukey HSD revelaron que hubo una interacción significativa entre grupo y tiempo para el bicarbonato de sodio en el mes 1 para el área manchada variable. Las pastas dentales que contenían carbón (Crest 3D con Charcoal y Colgate Essentials) y las pastas de dientes que no contenían carbón (Optic White) solo produjeron una eliminación significativa de las manchas en el intervalo de 6 meses.

Color stability of gingiva-colored restorative materials: an in vitro study.

The aim of this research was to determine the color stability of 3 gingival shades of dental restorative materials, Amaris Gingiva, Beautiful II Gingiva, and PermaFlo Pink, compared to a tooth-colored nanohybrid composite, Filtek Z250. Twenty-five specimens of each composite were fabricated in polytetrafluoroethylene-coated stainless steel molds and polished using a 4-step polishing regimen. The specimens were randomly assigned to groups for immersion in 1 of 5 solutions (n = 5): distilled water (control), red wine, tea, coffee, or curry (curry powder [containing turmeric] in a solution with distilled water). A desktop spectrophotometer was used to perform color measurements within the Commission Internationale de l'Eclairage L*a*b* color space, and mean overall color (E*) was calculated for each group before and after immersion for 7 days. The mean E* values of each composite before and after immersion were compared using paired t tests at the P < 0.05 level of significance. For all of the tested restorative materials, immersion in a solution of curry produced the greatest increase in mean E* values (P < 0.0001), with E* increasing 32-fold for Amaris Gingiva specimens, 27-fold for Beautiful II Gingiva, 34-fold for PermaFlo Pink, and 2-fold for Filtek Z250. There were smaller, but still significant, increases in E* for Amaris Gingiva, Beautiful II Gingiva, and PermaFlo Pink when immersed in coffee (P < 0.05). Curry caused the greatest change in E* values for all of the tested restorative materials, indicating that curry seasonings based on turmeric can cause unacceptable color change in all of the tested materials and such change can happen in a relatively short time. Coffee also has the potential to cause unacceptable color change in gingival shades of composite materials.

A Comparative Assessment of the Surface Roughness of Thermoplastic Denture Base Resins Following Adjustment and Re-Polishing

This study assessed the roughness of two injection-molded, thermoplastic materials used for denture bases compared with a polyamide material and compression molded Polymethylmethacrylate (PMMA) after the adjustment and re-polishing with either a laboratory protocol or a chair side protocol. Methods: Forty specimens, each of PMMA, Valplast, DuraFlex, Dura Cetal were fabricated and finished according to individual manufactures' instructions. These materials were adjusted with tungsten carbide (TC) burs to mimic gross adjustments, and then re-polished either on a lathe or bonded silicon carbide (B-SC). Following instrumentation, the specimens were assessed using contact profilometry and scanning electron microscopy. Two-factor ANOVA was used to determine significant differences in mean surface roughness (Ra and Rmax), with included factors being material type and re-polishing regimen. Results: Mean Ra values ranged from 0.26 (DuraFlex control) to 1.82 (Valplast adjusted with TC burs). Mean Rmax values ranged from 1.88 (Dura Flex control) to 13.76 (Valplast adjusted with TC burs). Two-factor ANOVA revealed that interaction of both factors was significant (p < 0.05) for Ra and Rmax. There was a statistically significant increase in both Ra (p < 0.05) and Rmax (p < 0.05) for all material types following the gross adjustment. With the exception of DuraFlex, re-polishing of samples that were previously adjusted with TC burs, on the dental lathe produced surfaces that were comparable to control samples. Conclusion: Adjustment of DuraFlex should be kept to a minimum since the adjustment produced the significant surface detriment that could not be corrected with either of the polishing regimens.

The Influence of Sonic and Ultrasonic Vibration on the Shear Bond Strength of a Selected Resin Luting Cement.

PURPOSE: This study determined the effect of sonic and ultrasonic instrumentation on the shear bond strengths of Panavia 21, a popular cement for the luting of resin-bonded restorations. METHODS: 84 Ni-Cr cylinders were cemented to randomly selected resin composite substrates using Panavia 21 following the manufacturer's instructions. The Ni-Cr-composite specimens were divided into 7 groups of 12 specimens each based upon the procedure used for removing the excess cement. For Group 1 (Co) specimens the excess cement was removed with microbrushes immediately after cementation. Groups 2 through 7 were based on the use of vibrating instrument and the time period after which the excess material was removed. These included the cement, Panavia 21, three vibrating instruments, Sonic with a universal tip (So), Piezoelectric ultrasonic with a USPIS tip (Pu), Magnetorestrive ultrasonic with a FS1-100 tip (Mu) and two different time periods, soon after cementation (9m) and one hour after cementation (1h). Once excess cement REMOVAL WAS COMPLETED, THE SPECIMENS WERE SUBJECTED TO SHEAR TESTING. RESULTS: Mean Shear Bond strengths ranged from 16.03 MPa (Co) to 19.91 MPa (So 1h). Statistical analysis demonstrated that interaction of the main effects were significant (F = 4.27, p = 0.042). Post-hoc analysis demonstrated that the effect of timing was significant in all the instrumented groups. The majority of the tested specimens failed cohesively compared to mainly adhesive failures for the control group. CONCLUSIONS: The effect of type of instrumentation immediately following polymerization setting had no effect on the shear bond strengths however a delay of 1 hour for all types of instrumentation had a beneficial effect of improving observed shear bond strengths.

The Influence of Sonic and Ultrasonic Vibration on the Shear Bond Strength of a Selected Resin Luting Cement

Purpose: This study determined the effect of sonic and ultrasonic instrumentation on the shear bond strengths of Panavia 21, a popular cement for the luting of resin-bonded restorations. Methods: 84 Ni-Cr cylinders were cemented to randomly selected resin composite substrates using Panavia 21 following the manufacturer's instructions. The Ni-Cr-composite specimens were divided into 7 groups of 12 specimens each based upon the procedure used for removing the excess cement. For Group 1 (Co) specimens the excess cement was removed with microbrushes immediately after cementation. Groups 2 through 7 were based on the use of vibrating instrument and the time period after which the excess material was removed. These included the cement, Panavia 21, three vibrating instruments, Sonic with a universal tip (So), Piezoelectric ultrasonic with a USPIS tip (Pu), Magnetorestrive ultrasonic with a FS1-100 tip (Mu) and two different time periods, soon after cementation (9m) and one hour after cementation (1h). Once excess cement REMOVAL WAS COMPLETED, THE SPECIMENS WERE SUBJECTED TO SHEAR TESTING. Results: Mean Shear Bond strengths ranged from 16.03 MPa (Co) to 19.91 MPa (So 1h). Statistical analysis demonstrated that interaction of the main effects were significant (F = 4.27, p = 0.042). Post-hoc analysis demonstrated that the effect of timing was significant in all the instrumented groups. The majority of the tested specimens failed cohesively compared to mainly adhesive failures for the control group. Conclusions: The effect of type of instrumentation immediately following polymerization setting had no effect on the shear bond strengths however a delay of 1 hour for all types of instrumentation had a beneficial effect of improving observed shear bond strengths.

A Nano-hybrid investigated: The correlation between surface characteristics and color after instrumentation

There is no evidence in the literature on the correlation between surface roughness of dental nanocomposites following application of instruments for finishing compared to instruments for both finishing and polishing and how this relates to the final color of the restoration. This study evaluated the correlation between roughness parameters (Ra and Rmax), of a nano-hybrid composite following finishing alone or finishing and polishing, and color. 70 specimens (8mmX8mmX2mm) of the nano-hybrid Heritage 7 were fabricated. One group of 10 specimens served as control. The remaining specimens of 10 per group were either finished sequentially with (a) diamonds (b) stones (c) carbides or finished and polished with (d) diamonds and Sof-lex discs (e) stones and Sof-lex discs, (f) carbides and Sof-lex discs. Following instrumentation the specimens were assessed using profilometry for surface roughness. Immediately following surface roughness measurements color was assessed using a spectrophotometer. Roughness and color data were assessed using a one-way analysis of variance (ANOVA) and post-hoc Bonferroni. Correlations between the color coordinates (L*a*b*) and ΔE and roughness parameters (Rmax and Ra) were analyzed at a 0.05 level of significance. There were no statistical changes in Ra measurements between finishing and finishing and polishing, however specimens finished with stones showed a dramatic change in Rmax values compared tocontrol and all the other finishing and finishing and polishing regimens. There was a correlation between Ra and color parameters L* and a* and ΔE. Green and white stones produced the most surface detriment in terms of surface roughness and color.

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.

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.

Abutment taper of full cast crown preparations by dental students in the UWI School of Dentistry.

Retention of crowns has been shown to be inversely proportional to taper. The objective of this study was to compare the abutment taper of teeth prepared for full veneer crowns by students at the UWI School of Dentistry with those of other dental schools. Twenty five dies were scanned by a Co-ordinate Measuring Machine (CMM) and the mean taper and standard deviations were found to be 20.3 +/- 11.3 degrees mesio-distally and 18.3 +/- 8.5 degrees bucco-lingually. This study shows that the taper achieved by dental students at the UWI School of Dentistry preparing teeth for full veneer crowns is comparable to those achieved by other dental students in the US, UK, Europe and Japan.

Perceived competency at graduation among dental alumni of the University of the West Indies.

The aims of this study were to describe levels of self-rated competency of dental graduates from the University of the West Indies (UWI) and to investigate relationships with gender and the effect of curriculum change. A thirty-two item self-reported postal questionnaire was sent to UWI dental alumni (1994-2002). The questionnaire included twenty-eight competencies that could be rated on a 5-point scale: 1 (not at all competent) to 5 (very competent). Overall preparedness for practice could also be rated from 1 (not at all prepared) to 5 (very prepared). The response rate was 77.4 percent, with a mean age of 29.3 years. Items with the highest mean scores were taking an adequate medical history (4.49), recognizing and treating dental caries (4.46), oral examination (4.36), and giving dental health education (4.35). Those with the lowest rating were designing and undertaking clinical research (2.29), dealing with practice management issues (2.52), designing and delivering crown and bridge work (3.33), and recognizing pathologic occlusions (3.33). Overall preparedness for practice was rated as 3.27. Female graduates rated four competencies significantly higher than males. Graduates exposed to the new curriculum perceived greater overall preparedness for general dental practice, suggesting the change to a competency-based curriculum was effective.