Computer-assisted learning and simulation lab with 40 DentSim units

There are an increasing number of studies about the computer-assisted dental patient simulator DentSim (DenX, Israel), by which dental students can acquire cognitive motor skills in a multimedia environment. However, only a very few studies have been published dealing with efficient ways to use and to manage a computer-assisted dental simulation lab with 40 DentSim units. The current approach and optimization steps of the College of Dentistry at the University of Tennessee Health Science Center were evaluated based on theoretical and practical tests and by questionnaires (partial 5-point Likert scale). Half of the D1 (first-year) students (2004/05) already had experience with computer-assisted learning at their undergraduate college and most of the students even expected to be taught via computer-assisted learning systems (83.5%) at the dental school. 87.3% of the students working with DentSim found the experience to be very interesting or interesting. Before the students carried out the preparation exercises, they were trained in the skills they needed to work with the sophisticated technology, eg, system-specific operation skills (66.6% attained maximal reachable points) and information searching skills (79.5% attained maximal reachable points). The indirect knowledge retention rate / incidental learning rate of the preparation exercises in the sense of computer-assisted problem-oriented learning regarding anatomy, preparation procedures, and cavity design was promising. The wide- ranging number of prepared teeth needed to acquire the necessary skills shows the varied individual learning curves of the students. The acceptance of, and response to, additional elective training time in the computer-assisted simulation lab were very high. Integrating the DentSim technology into the existing curriculum is a way to improve dental education, but it is also a challenge for both teachers and the students. It requires a shift in both curriculum and instructional goals that have to be reevaluated and optimized continuously.

Computer-assisted learning and simulation systems in dentistry--a challenge to society

INTRODUCTION

Computer technology is increasingly used in practical training at universities. However, in spite of their potential, computer-assisted learning (CAL) and computer-assisted simulation (CAS) systems still appear to be underutilized in dental education.

MATERIALS AND METHODS

Advantages, challenges, problems, and solutions of computer-assisted learning and simulation in dentistry are discussed by means of MEDLINE, open Internet platform searches, and key results of a study among German dental schools.

RESULTS

The advantages of computer-assisted learning are seen for example in self-paced and self-directed learning and increased motivation. It is useful for both objective theoretical and practical tests and for training students to handle complex cases. CAL can lead to more structured learning and can support training in evidence-based decision-making. The reasons for the still relatively rare implementation of CAL/CAS systems in dental education include an inability to finance, lack of studies of CAL/CAS, and too much effort required to integrate CAL/CAS systems into the curriculum.

CONCLUSION

To overcome the reasons for the relative low degree of computer technology use, we should strive for multicenter research and development projects monitored by the appropriate national and international scientific societies, so that the potential of computer technology can be fully realized in graduate, postgraduate, and continuing dental education.

Two-year clinical comparison of a microfilled and a hybrid resin-based composite in non-carious Class V lesions

The purpose of this double-blind clinical trial was to compare the retention rate in noncarious Class V lesions of two resin-based composite restorative materials with contrasting stiffness. Isolation with retraction cord, pressed paper triangles, and cotton rolls was used to closely mimic the procedures generally used in a practice setting. Thirty pairs of restorations were placed, one using Silux Plus and one using Z100. The assignment of material was randomized, and the subjects were unaware of the material used. All restorations were placed with a fourth-generation adhesive liner, Scotchbond Multi-Purpose. Evaluations were performed at baseline, 6, 12, 18, and 24 months by two independent examiners using criteria developed by Cvar and Ryge in a forced consensus model. Examiners were unaware of the restoration's group identity. No difference between the retention rates for the two groups was found after 24 months, bringing into question the role that a material's stiffness plays in determining retention in a noncarious Class V lesion.

Two-year clinical performance of a resin-modified glass-ionomer restorative material

This study was a 2-year clinical evaluation of a conventional and a resin-modified glass-ionomer restorative material. Thirty-four restorations each of Ketac-Fil and Photac-Fil were placed without tooth preparation in cervical abrasion/abfraction lesions, primarily in premolar teeth. Patients ranged in age from 30 to 73 years, with a median age of 45 years. Isolation for the restorations was accomplished with cotton rolls. Restorations of both materials were retained at the rate of 93%, and both were comparable in appearance, receiving Alfa ratings for more than 85% of the restorations. One occurrence of secondary caries was observed for each material. No significant difference between the materials was observed for any evaluation category (exact binomial test, P > 0.05).

Retention of microfilled and hybrid resin-based composite in noncarious Class 5 lesions: a double-blind, randomized clinical trial

This double-blind clinical trial was undertaken to compare the retention rate of restorative materials with contrasting stiffness in noncarious class 5 lesions. All restorations were placed using retraction cord and cotton roll isolation to more closely mimic the general practice setting. Thirty subjects with at least two lesions were recruited to participate in the study. Each subject received one restoration using Silux Plus and one using Z100. The assignment of material was randomized, and the subjects were unaware of which tooth had received which material. All restorations were placed with a fourth-generation adhesive liner, Scotchbond Multi-Purpose. Evaluations were performed at baseline, 6, and 12 months by two independent examiners unaware of the restoration's group identity. The restorations were evaluated using criteria developed by Cvar and Ryge in a forced-consensus model. Despite the fact that the two materials have widely different elastic modulus values, after 12 months no difference between the retention rates for the two groups was found, and both groups of restorations performed very well.

Microleakage of Class V compomer and light-cured glass ionomer restorations

STATEMENT OF PROBLEM

Resin-modified (light-cured) glass ionomer and polyacid-modified composite resin (compomer) restorations are popular choices for the restoration of root caries and cervical abrasion/erosion lesions, but clinical studies are relatively few and have been published primarily as abstracts.

PURPOSE

In the absence of adequate clinical data, the marginal integrity of restorations of the above two types of material was compared in vitro. The microleakage of restorations of two light-cured glass ionomer restorative materials and of one compomer material was evaluated.

METHODS AND MATERIAL

Restorations of the three materials were placed in facial and lingual Class V cavity preparations in bovine incisors. All preparations were centered on the cementoenamel junction and were prepared with 45-degree enamel bevels. After thermal cycling, teeth were immersed in methylene blue dye, then sections of the restorations (n = 16) were visually evaluated.

RESULTS

Dye penetration was observed at approximately 20% of restoration margins for all three materials, with the greatest incidence of severe leakage in the compomer restorations.

CONCLUSION

No significant difference in microleakage among the three materials (ANOVA; p > 0.05) was found.

Preventive resin restorations vs. amalgam restorations: a three-year clinical study

A three-year clinical study was completed at the College of Dentistry comparing the overall performance of Class I amalgam restorations with preventive resin restorations (PRRs). Seventy-four PRRs and fifty-two amalgam restorations were placed in the posterior teeth of thirty-eight patients. The PRR was composed of two materials: P-50 (3M Corp.), a heavily filled composite resin, and White Sealant (3M Corp.), a light-cured sealant. Fast-set Dispersalloy (Johnson and Johnson Corp.) was used for the amalgam restorations. The restorations were evaluated at six months, one year, two years and three years. The USPHS/Ryge system was used to evaluate anatomic form, marginal adaptation, marginal discoloration and recurrent caries of both type restorations. A restoration was considered a failure if any part of the restoration was replaced due to secondary caries. There were two failures of PRRs at six months, and four failures at one year. Failures were due to non retention of the sealant of the PRR and possibly related to operator error. The failures were easily repaired and removed from the study. No PRR failed at the two or three year evaluations. No amalgam restoration failed within the three year period.

Effect of finishing method on the microleakage of Class V resin composite restorations

PURPOSE

To evaluate the effect of three finishing methods on the microleakage of Class V hybrid resin composite.

MATERIALS AND METHODS

Facial and lingual Class V cavities were prepared at the cemento-enamel junction of bovine incisors. Restorations of the two materials (Z100; Prodigy) were placed, using the supplied dentin-adhesives (Scotchbond Multipurpose; OptiBond FL, respectively). Finishing methods were carbide (C) and diamond (D) finishing instruments operated at high-speed, and finishing disks (S). After thermal cycling, the teeth were immersed in methylene blue dye, then sections of the restored teeth (n = 12) were visually assessed for leakage.

RESULTS

No leakage was observed at the resin-enamel interface in any restoration. At gingival margins, the incidence of leakage (slight/severe) was: Z100 D = 4/3, C = 5/3, S = 2/0; Prodigy D = 3/0, C = 2/4, S = 3/2. The greatest incidence of leakage was observed in restorations finished with carbide finishing burs. A two-way ANOVA of leakage data rankings showed no significant difference among the three methods (P = 0.07) or between the two materials (P = 0.55), and no significant interaction of material and finishing method (P = 0.07).

Pulpal response to dentin etched with 10% phosphoric acid

PURPOSE

To histopathologically evaluate the effect of etching sound dentin with 10% phosphoric acid, in cavities prepared just within the DEJ on young patients.

MATERIALS AND METHODS

Twenty-four orthodontic patients who required premolar extractions were selected for the study. Each of the patients had facial Class V resin composite restorations placed in two maxillary premolars selected for extraction. Each preparation was cut circular, 2 mm in circumference and 0.5 mm into dentin. The dentin of one maxillary premolar preparation, randomly selected, was etched with 10% phosphoric acid (Bisco) for 20 seconds. This was followed by the placement of a dentin bonding agent (All-Bond 2) and a microfilled composite restoration (Silux). The contralateral maxillary premolar, received a similar preparation, but the dentin surface was lined with a light-cured glass ionomer liner before etching of the enamel, followed by placement of a dentin bonding agent and a microfilled resin composite restoration. One of the mandibular premolars was randomly selected as a negative control, having no treatment. Fourteen days after the placement of the restorations, the teeth were extracted, and histologically examined for insult to the pulpal tissues. Injury to the pulp was evaluated by quantitative measures of histopathology, including necrosis, infiltration by inflammatory cells, and other indicators of tissue injury.

RESULTS

Using a Kruskal-Wallis analysis, there was no statistically significant difference in pulpal histopathology of the teeth with etched dentin versus teeth with dentin protected by a liner or the negative control teeth (P < 0.05).

Microleakage of composite resin restorations with a 10 percent maleic acid etchant

Microleakage of Class V composite resin restorations with margins all in enamel were compared in this in-vitro study using Scotchbond MultiPurpose Adhesive (SMP) (3M Corp.), and Scotchbond II (SB II) (3M Corp). Twenty extracted human molars were randomly separated into two groups: Group One, which used the SMP system and Group Two, which used the SB II system. Circular Class V preparations were cut 1.8 mm deep and 3 mm in diameter using a #556 fissure bur. Cavosurface margins, all in enamel, were beveled. The enamel and dentin were treated following manufacturer's directions for each group, and a microfilled composite resin, Silux Plus (3M Corp), was applied in two hand-placed increments. All teeth were finished with Sof-Lex discs, stored in water for seven days, then thermocycled in a water bath for 100 cycles, alternating from 4 degrees C to 58 degrees C. The teeth were placed in a 5 percent solution of methylene blue, rinsed and then invested in resin. All teeth were sectioned vertically and horizontally and a ratio (percentage) of wall length to amount of leakage along each wall was established. The overall mean leakage of Group One was 15.27 percent and Group Two was 13.84 percent. Looking at individual walls, the mean occlusal wall leakage of Group One was 28.41 percent and Group Two was 12.45 percent. Mean gingival wall leakage of Group One was 15.96 percent and Group Two was 21.80 percent. Comparing the two groups, using a student's t test, there was no significant difference between the overall mean leakage or between the gingival wall leakage (p > 0.05); however, there was a significant difference between the occlusal wall leakage (p < 0.05), with SMP exhibiting more leakage.

Posterior tooth replacement with a full crown and acid-etched wing as retainers

With the advent of stronger adhesive materials and preparations that increase retention and lateral stability, acid-etched retainers provide an alternative approach to fixed bridges. Preparations for acid-etched retainers are more conservative, but may be more difficult to accomplish. Factors that must be considered to ensure successful cases include proper case selection, attention to preparation techniques, impression techniques, moisture control and cementation techniques.

Microleakage of composite resin restorations with various etching times

Microleakage was assessed in Class V composite resin restorations, placed in extracted noncarious human premolar teeth after the enamel cavosurface margins of the preparations had been etched with phosphoric acid for 5, 15, or 30 seconds. The restored teeth were thermocycled, placed in methylene blue dye, invested, and sectioned. The extent of dye penetration along the tooth-restoration interface in the three etching groups was compared. The group etched for 5 seconds showed the greatest leakage; leakage was statistically significantly greater than that in the groups etched for 15 or 30 seconds. The tooth-restoration interface at the occlusal and gingival margins showed more leakage than did the mesial or distal margins.

Two-year clinical evaluation of preventive resin restorations

A three-year clinical study is being conducted at the University of Tennessee, Memphis, college of Dentistry, comparing occlusal wear of Class I amalgam restorations with preventive resin restorations. This paper will concentrate on the two-year results of the preventive resin restoration with regards to placement technique, wear as evaluated by the USPHS system, marginal adaptation, recurrent caries, marginal discoloration, and address problems encountered.

Three-year occlusal wear of posterior composite restorations

The specific aims of this study were to: 1) measure the occlusal wear of four different dental composite materials placed in the posterior teeth of adults; and 2) evaluate the effect of the clinical parameters, cavity class and tooth type on occlusal wear. Four different visible light-cured composite materials were used to make the restorations in this study. The restorations placed for this randomized clinical trial were scored through the use of an indirect evaluation system (M-L scale). The total sample size per recall ranged from 90 to 142 restorations from baseline to 36 months. The mean wear at 36 months for Heliomolar, J&J Experimental (Adaptic II) and P-30 was 45-54 microns, which is rather low compared to the recently reported wear of other composite materials. Marathon exhibited significantly greater wear with a mean of 174 microns at 36 months. The data also showed that cavity class and tooth type had no significant effect on the occlusal wear of the restorations made with the three low wear-rate materials, while restorations composed of the high wear-rate material exhibited more wear in molars than premolars; this effect was again not statistically significant. These data support the hypothesis that the overall wear of a composite restoration is more dependent on the material's properties than clinical parameters such as cavity class and tooth type.

Direct and indirect evaluation of posterior composite restorations at three years

The purpose of this study was to compare the use of direct (USPHS) and indirect (M-L) systems of evaluating the occlusal wear of posterior composite restorations. Additionally, this study has utilized the USPHS method to compare the in vivo performance of posterior resin composite restorations made from four different visible-light-cured materials. Of the 202 restorations placed for this randomized clinical trial, only those restorations that were scored by both direct and indirect evaluation systems were included in these comparisons. Restorations were evaluated by two calibrated examiners from baseline to 36 months. While there were some differences noted among the four materials, the majority (99%) of the restorations evaluated in this study received "alpha" or "bravo" scores for all USPHS parameters, indicating acceptable in vivo performance. The results of this study also indicate that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems. For those restorations that changed anatomic form scores, the mean wear at the alfa/bravo transition was 100 +/- 80 microns. By the 24-month recall examination, the use of the USPHS evaluation system category of anatomic form enabled examiners to differentiate restorations and materials that had experienced little occlusal wear from those that had experienced greater amounts of wear.

The effectiveness of sodium fluoride iontophoresis in patients with sensitive teeth

This study investigated the use of iontophoresis in altering the sensitivity level of teeth that displayed thermal and tactile hypersensitivity. A total of 95 teeth were treated with an iontophoresis instrument. Forty-eight of these teeth were treated with a placebo of deionized water, and 47 were treated with a 2% sodium fluoride solution. Two of the 47 teeth receiving sodium fluoride had identical pretreatment and posttreatment sensitivity ratings, while 40 teeth (85.1%) demonstrated a reduction in sensitivity. Twenty-nine of the 48 teeth receiving the placebo demonstrated no change in sensitivity. All teeth receiving the placebo were re-treated with sodium fluoride. Forty-seven (97.9%) responded with reduced levels of sensitivity.

Resin-to-enamel bond strengths with various etching times

It has been advocated recently that etching times of enamel be reduced from 60 seconds to as low as 15 seconds. However, the minimal etching time needed to achieve adequate retention of composite resin to enamel has not been identified. In this study, an attempt was made to find the minimal enamel-etching time that still allowed adequate bond strength of composite resin to enamel surfaces. Adequate bond strength was defined as equivalent to the bond strength established for the conventional 60-second etch. Results seemed to indicate that a 5-second etch was sufficient to allow adequate bond strength; however, further study is required to determine the effects of short etching times on microleakage.