Marginal adaptation and internal indentation resistance of a Class II bulk-fill resin-based composite.

PURPOSE: To compare the dentin bonded external marginal integrity and the internal surface indentation hardness of bulk-fill and conventional resin-based composite (RBC) placed in both bulk and increments. METHODS: 120 MO and DO cavities were prepared in 60 extracted human third molars. The teeth were randomly divided into four groups of 15 teeth per group to be restored as follows: BB (bulk-fill RBC, placed in a 4 mm bulk increment), BL (bulk-fill RBC, placed in 2 mm incremental layers), CB (conventional RBC, placed in a 4 mm bulk increment), and CL (conventional RBC, placed in 2 mm incremental layers). Marginal gaps were measured at mesial and distal dentin gingival cavosurfaces of each tooth using scanning electron microscopy of epoxy resin replicas and Knoop hardness (KHN) was measured at three different RBC depths (1.8, 2.8 and 3.8 mm). Statistical analyses included one-way ANOVA with post-hoc Tukey's HSD, and paired-sample t-test or a nonparametric Wilcoxon signed-rank test, as appropriate. RESULTS: There was no significant effect of RBC restoration type on external marginal gap at the distal surface or at the mesial surface among the four groups tested (P> 0.05 in each instance), while no significant difference in external marginal gap was found between the mesial and distal surfaces within groups (P> 0.05 in each instance). The mean RBC internal surface KHN at 1.8 mm depth was significantly greater than at 2.8 mm and 3.8 mm depths in all tested groups (P< 0.05 for all instances), with a similar mean internal hardness between all groups. The bulk-fill RBC restorations demonstrated similar marginal gap formation and Knoop hardness to conventional universal RBC restorations under the conditions of this study. CLINICAL SIGNIFICANCE: Bulk-fill resin-based composite (RBC), from the perspective of marginal adaptation and internal hardness, may be a suitable alternative to conventional RBC.

Comparison of light propagation in dental tissues and nano-filled resin-based composite.

OBJECTIVE: This study used three LASERs (red, green, and blue) with a spectrophotometer to compare the light propagation for the following: absorption (A), transmittance (T), attenuation (K), and scattering anisotropy coefficient (g) in dental tissues and nano-filled resin-based composites. This study used three distinct incremental build-up techniques, which included one shade (body), two shades (enamel and dentin), and three shades (enamel, transparent, and dentin). METHODS: Twenty human, un-erupted, recently extracted third molars (shade B1) were used to obtain 40 tooth slabs. The samples were randomized and equally distributed into four experimental groups. The Positive Control Group included dental tissues with enamel, dento-enamel junction DEJ, and dentin; the Technique 1 group (T1) included one shade tissues, B1B; the Technique 2 group (T2) included two-shades tissues, A2Dentin and B1Enamel; and the Technique 3 group (T3) included three shade tissues, A2Dentin, Transparent, and B1Enamel. Cavity preparation was standardized, and, using the spectrophotometer, each specimen was irradiated by three LASERs. A voltmeter recorded the light-output signal, and from this raw data, the following optical constants (A, T, K, g) were calculated. RESULTS: ANOVA, followed by a post hoc Tukey's test (p < 0.05), revealed that absorption and transmittance in dental tissues were significantly different when comparing the three build-up technique groups. However, when examining attenuation coefficient, there was no significant difference in dental tissues for T2 and T3 as analyzed by blue and red lasers. There was also no significant difference among the three lasers for T2 and T3. There was also no significant effect of the types of experiments on the value of scattering anisotropy factor g for blue laser among the four experimental groups. CONCLUSION: Within the limitations of this study, none of the build-up techniques were able to reproduce the dental tissues optical properties, and T2 and T3 resulted in a similar pattern of light propagation. CLINICAL SIGNIFICANCE: The clinical success of restorative procedures depends on selecting materials and techniques that emulate the natural tooth and provide long-term stability in color and optical properties.

Evaluation of an Innovative Digital Assessment Tool in Dental Anatomy.

AIM: The E4D Compare software is an innovative tool that provides immediate feedback to students' projects and competencies. It should provide consistent scores even when different scanners are used which may have inherent subtle differences in calibration. This study aimed to evaluate potential discrepancies in evaluation using the E4D Compare software based on four different NEVO scanners in dental anatomy projects. Additionally, correlation between digital and visual scores was evaluated. MATERIALS AND METHODS: Thirty-five projects of maxillary left central incisors were evaluated. Among these, thirty wax-ups were performed by four operators and five consisted of standard dentoform teeth. Five scores were obtained for each project: one from an instructor that visually graded the project and from four different NEVO scanners. A faculty involved in teaching the dental anatomy course blindly scored the 35 projects. One operator scanned all projects to four NEVO scanners (D4D Technologies, Richardson, TX, USA). The images were aligned to the gold standard, and tolerance set at 0.3 mm to generate a score. The score reflected percentage match between the project and the gold standard. One-way ANOVA with repeated measures was used to determine whether there was a significant difference in scores among the four NEVO scanners. Paired-sample t-test was used to detect any difference between visual scores and the average scores of the four NEVO scanners. Pearson's correlation test was used to assess the relationship between visual and average scores of NEVO scanners. RESULTS: There was no significant difference in mean scores among four different NEVO scanners [F(3, 102) = 2.27, p = 0.0852 one-way ANOVA with repeated measures]. Moreover, the data provided strong evidence that a significant difference existed between visual and digital scores (p = 0.0217; a paired - sample t-test). Mean visual scores were significantly lower than digital scores (72.4 vs 75.1). Pearson's correlation coefficient of 0.85 indicated a strong correlation between visual and digital scores (p < 0.0001). CONCLUSION: The E4D Compare software provides consistent scores even when different scanners are used and correlates well with visual scores. CLINICAL SIGNIFICANCE: The use of innovative digital assessment tools in dental education is promising with the E4D Compare software correlating well with visual scores and providing consistent scores even when different scanners are used.

Dental anatomy grading: comparison between conventional visual and a novel digital assessment technique.

Conventional grading of dental students' projects in preclinical courses has mainly relied on visual evaluation by experienced instructors. The purpose of this study was to compare conventional visual grading in a dental anatomy course at one U.S. dental school to a novel digital assessment technique. A total of sixty samples comprised of two sets of faculty wax-ups (n=30), student wax-ups (n=15), and dentoform teeth of tooth #14 (n=15) were used for this study. Two additional faculty members visually graded the samples according to a checklist and then repeated the grading after one week. The sample wax-up with the highest score based on the visual grading was selected as the master model for the digital grading, which was also performed twice with an interim period of one week. Descriptive statistics and signed rank tests for systematic bias were used for intra- and interrater comparisons. The intraclass correlation (ICC) was used as a measure of intra- and interrater reliability. None of the faculty members achieved the minimum acceptable intrarater agreement of 0.8. Interrater agreement was substantially less than intrarater agreement for the visual grading, whereas all measures of intrarater agreement were greater than 0.9 and considered excellent for the digital assessment technique. These results suggest that visual grading is limited by modest intrarater reliability and low interrater agreement. Digital grading is a promising evaluation method showing excellent intrarater reliability and correlation. Correlation for visual and digital grading was consistently modest, partly supporting the potential use of digital technology in dental anatomy grading.

Consumers' choice of dentists: how and why people choose dental school faculty members as their oral health care providers.

This study aimed to better understand how and why people choose dental school faculty members as their oral health care providers. Increasing financial constraints in U.S. dental schools have led their administrators to seek alternative funding sources, one of which can be revenues from dental school faculty practice. To effectively promote faculty practice, it is necessary to understand how and why one chooses a dental school faculty member as his or her oral health care provider. A survey of 1,150 dental school faculty practice patients who recently chose their dentist was conducted, and 221 responded. The information sources these respondents said they used and rated highly were other dentists, friends, family members, clinic website, the Internet, and the insurance directory. Dentist-related attributes that were perceived to be important were quality of care, professional competence of dentist, and explanation of treatment/patient participation in the treatment decision. Dental practice-related attributes perceived to be important were the ability to get appointments at convenient times, reasonable waiting time to get appointments, and attitude/helpfulness of staff. This study found that traditionally popular (family, friends) and newly emerging information sources (the Internet, clinic website, and insurance directory) were both used and perceived to be important by patients of the dental school faculty practice. Dental schools and dentists can use this study's findings to select appropriate communication channels to promote their practices and to focus on attributes that dental consumers value the most.

Development and evaluation of an interactive dental video game to teach dentin bonding.

Written and clinical tests compared the change in clinical knowledge and practical clinical skill of first-year dental students watching a clinical video recording of the three-step etch-and-rinse resin bonding system to those using an interactive dental video game teaching the same procedure. The research design was a randomized controlled trial with eighty first-year dental students enrolled in the preclinical operative dentistry course. Students' change in knowledge was measured through written examination using a pre-test and a post-test, as well as clinical tests in the form of a benchtop shear bond strength test. There was no statistically significant difference between teaching methods in regards to change in either knowledge or clinical skills, with one minor exception relating to the wetness of dentin following etching. Students expressed their preference for an interactive self-paced method of teaching.

Effect of pre-heated composites and flowable liners on Class II gingival margin gap formation.

PURPOSE: To evaluate the effect of preheated composites (PHC) and flowable liners (FL) on the gingival margin gap formation of Class II composite restorations compared to the placement of room temperature composites (RTC). MATERIALS AND METHODS: Class II composite restorations were prepared on 40 extracted mandibular third molars, with the gingival margin located 1 mm below the CEJ in dentin. Optibond FL (Kerr), microhybrid Filtek Z-250 (3M ESPE) and Flow-It (Jeneric Pentron) were used to evaluate five study groups: 1) PHC, 130 degrees F/54.4 degrees C; 2) PHC, 155 degrees F/68.3 degrees C; 3) FL cured prior to the first increment composite; 4) FL cured simultaneously with the first increment composite and 5) RTC (Control). Impressions were taken with quick set polyvinyl siloxane impression material, and epoxy resin replicas were evaluated under SEM (200x). Gingival margin adaptation was quantitatively evaluated in terms of percentage of gap formation according to a modified ordinal scoring criteria. All margins were evaluated twice for reliability assessment. A non-parametric Kruskal-Wallis test was used to determine whether significant differences in gap formation existed among the study groups. RESULTS: A high level of agreement was observed between duplicate measurements of the percentage of gap formation (intra-class correlation = 0.956, p < 0.0001). There was no evidence of a difference among groups defined by placement technique (p = 0.82). Overall, the mean gap-percentage for the 40 margins evaluated was 6.3 (Median = 1.1; SD = 14.8). CONCLUSIONS: Gingival margin adaptation was not improved relative to the control by any of the placement techniques tested. No significant differences in gap formation were found among the study groups. A high degree of intra-examiner reliability was confirmed.

Evaluation of an audience response system in a preclinical operative dentistry course.

Student performance was compared on written and psychomotor skill tests of freshman dental students receiving conventional lectures versus the same lectures containing interactive components using TurningPoint, a wireless audience response system (ARS). The research design was a controlled crossover study with seventy-seven freshman dental students conducted in a preclinical operative dentistry course. Two randomized groups alternated the two study lectures, one with ARS and the other without ARS. Student knowledge retention was measured through written examination using immediate posttest, as well as questions on the unit and final examinations. Psychomotor skill tests were given on both lecture topics. Statistically significant differences indicating superiority of ARS were identified for performance on the immediate posttest and psychomotor skill test only for the lecture "Principles of Dental Bonding." The other examinations/skill testing showed no significant difference. These results indicate that ARS is a promising teaching tool for dental education.

The inhibitory effect of MI paste, fluoride and a combination of both on the progression of artificial caries-like lesions in enamel.

This in-vitro study evaluated the inhibition of demineralization in enamel sections produced by MI paste, fluoride and a combination of both, compared to artificial saliva and NaF 5000 ppm in a caries progression pH-cycling model. Twenty-one teeth were demineralized to create subsurface enamel lesions (approximately 200 microns in depth). The teeth were sectioned and characterized using polarized-light-microscopy (PLM). A single section from each lesion was assigned to a treatment group: Artificial saliva, NaF 5000 ppm (Prevident, Colgate), MI paste (Recaldent, GC America Inc), NaF 1100 ppm (Crest, Procter & Gamble) and NaF 1100 ppm plus MI paste. The sections were covered with varnish except for an exposed window on the external surface of the lesion and placed in a six-day pH-cycling model with two daily treatment applications of two minutes each. The sections were characterized by PLM, and the lesion areas were measured using a digital image analysis system. Based on a paired-sample t-test, significant differences (p < .05) in percentage of change in lesion size were found between the high fluoride group and all the other groups. No significant difference was found between the artificial saliva and MI paste group, neither was there any significant difference between the NaF 1100 ppm, the combined application group or the MI paste group alone. In conclusion, the higher concentration of NaF (5000 ppm) reduced lesion progression to the greatest extent. The MI paste group did not show any effect on the inhibition of lesion progression. Further studies on the preventive effect and longer treatment applications are recommended.

Effect of self-etchant pH on the shear bond strength of orthodontic brackets.

INTRODUCTION: Self-etching primers (SEPs) have been used successfully during bonding to reduce technique sensitivity while minimizing the etching of enamel. Although serving the same purpose, SEPs differ in acidity and aggressiveness. Thus, the purpose of this study was to determine whether the pH of SEPs affects the shear bond strength of orthodontic brackets. METHODS: Forty-five molars were cleaned, mounted, and randomly divided into 3 groups with different SEPs: in group 1 (control), 15 orthodontic brackets were bonded to the teeth with Transbond Plus (3M Unitek, Monrovia, Calif) with a pH of about 1.0; in group 2, 15 brackets were bonded with Adper Prompt L-Pop (3M ESPE, St Paul, Minn) with a pH of 0.9 to 1.0; in group 3, 15 brackets were bonded with Clearfil S3 Bond (Kuraray America, New York, NY), with a pH of 2.7. All teeth were bonded with Transbond XT paste (3M Unitek). The teeth were debonded within half an hour after initial bonding by using a universal testing machine. The residual adhesive on each tooth was evaluated. ANOVA was used to compare the shear bond strength (SBS) of the 3 groups, and the chi-square test was used to compare the adhesive remnant index (ARI) scores for the 3 groups. RESULTS: ANOVA indicated significant differences between the groups. The Duncan multiple range test indicated that Clearfil S3 Bond produced a significantly stronger mean SBS (6.5 +/- 1.9 MPa) than the Transbond Plus system (mean, 4.2 +/- 1.9 MPa). No significant differences were seen between the SBS of the brackets bonded with Adper (mean, 5.9 +/- 3.4 MPa) and the other 2 groups. The comparisons of the ARI scores between the 3 groups indicated that bracket failure mode was not significantly different. CONCLUSIONS: The SEP with the highest pH (least acidic), Clearfil S3 Bond, bonded brackets successfully and with the strongest SBS; this suggests that the pH of the SEP is not the primary determinant of the SBS. The clinician should be aware that some SEPs can leave the enamel surface healthier after debonding.

Core buildup repair using a clear matrix: a case report and clinical technique.

The fracture of core buildup material is common in dental practice. This article describes a core buildup repair technique utilizing a custom matrix. This technique enables the dentist to reestablish the original contour and alignment of the broken core buildup and assures excellent crown fit in a short amount of time with a predictably successful outcome.

Evaluation of modifying the bonding protocol of a new acid-etch primer on the shear bond strength of orthodontic brackets.

The purpose of the study was to evaluate the shear bond strength of orthodontic brackets when light curing both the self-etch primer and the adhesive in one step. Fourty eight teeth were bonded with self-etch primer Angel I (3M/ESPE, St Paul, Minn) and divided into three groups. In group I (control), 16 teeth were stored in deionized water for 24 hours before debonding. In group II, 16 teeth were debonded within half-an-hour to simulate when the initial archwires were ligated. In group III, 16 additional teeth were bonded using exactly the same procedure as in groups I and II, but the light cure used for 10 seconds after applying the acid-etch primer was eliminated, and the light cure used for 20 seconds after the precoated bracket was placed over the tooth. This saved at least two minutes of the total time of the bonding procedure. The teeth in this group were also debonded within half-an-hour from the time of initial bonding. The teeth debonded after 24 hours of water storage at 37 degrees C had a mean shear bond strength of 6.0 +/- 3.5 MPa, the group that was debonded within half-an-hour of two light exposures had a mean shear bond strength of 5.9 +/- 2.7 MPa, and the mean for the group with only one light cure exposure was 4.3 +/- 2.6 MPa. Light curing the acid-etch primer together with the adhesive after placing the orthodontic bracket did not significantly diminish the shear bond strength as compared with light curing the acid-etch primer and the adhesive separately.

Impression matrix technique for cusp replacement using direct composite resin.

UNLABELLED: Placement of Class II composite resin restorations often presents unique challenges in achieving proper contour and contact. Although the use of sectional bands has provided solutions to these problems, their use typically is limited to more ideal cavity preparations. With more extensive loss of tooth structure, recreating the natural tooth contours and contacts with direct resin composite can be difficult. Typically an indirect restoration is the treatment of choice when a cusp is lost. However, situations may arise that require the use of direct resins for cusp replacement. This article describes the use of an impression matrix to facilitate the replacement of missing tooth structure and allow the dentist to use sectional bands in certain cusp loss situations. CLINICAL SIGNIFICANCE: When applicable, the impression matrix provides a significant saving in time and effort in cusp replacement with direct composite resins.

The effect of saliva contamination on shear bond strength of orthodontic brackets when using a self-etch primer.

The purpose of this study was to assess the effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer. Brackets were bonded to 52 extracted human molars according to one of the following four protocols. Group I (uncontaminated control): A self-etch acidic primer, Angel I (3M/ESPE Minneapolis, Minn) was placed on the enamel for 15 seconds, gently dried with air, and light cured for 10 seconds. Precoated brackets APC II (3M Unitek, Monrovia, Calif) were then placed on the teeth and light cured for 20 seconds. Group II: The enamel surface was first contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The bonding procedure was then repeated as in group I. Group III: The self-etch primer was applied for 15 seconds, gently dried with air, and light cured for 10 seconds. The surface was then contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The precoated brackets were then bonded as in groups I and II. Group IV: The enamel surface was contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The self-etch primer was applied. The surface was then re-contaminated with human saliva for 10 seconds, blown off with an air-syringe for five seconds. The precoated brackets were then bonded as in groups I, II, and III. The results of the analysis of variance (F = 4.79) indicated that the shear bond strengths of the four groups were significantly different (P = .005). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=1.7+/-1.4 MPa) shear bond strength than either the control group (=6.0+/-3.5 MPa) or the groups where contamination occurred either before (=4.8+/-3.3 MPa) or after (=4.8+/-3.3 MPa) the application of the primer. The new acid-etch primer can maintain adequate shear bond strength if contamination occurs either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer significantly reduced the shear bond strength of orthodontic brackets.