Reduction of discrepancies between students and instructors in the assessment of practical tasks through structured evaluation sheets and peer feedback.

The aim of this study was to reduce discrepancies between students and instructors in a preclinical dental course by employing structured peer feedback based on a detailed evaluation sheet. In a crossover study of dental students (n = 32), which compared peer feedback using an evaluation sheet (test) with the traditional method (control), participants completed tasks involving cavity and partial crown preparation. The practical tasks were scored numerically on a scale ranging from one (excellent) to six (failure). The amount of feedback provided by the instructor was also recorded. Statistical analysis was conducted using Wilcoxon signed-rank tests (p < 0.05). Regarding cavity preparation, no statistically significant difference was observed (median (25th-75th percentile)) between the grades received by the test (2.00 (1.50-3.00)) and control groups (2.25 (2.00-3.00)). However, the grades pertaining to partial crown preparation exhibited a statistically significant difference between the test (2.25 (2.00-2.50)) and control (2.50 (2.00-3.00)) groups. LimeSurvey and five-finger feedback were used to assess satisfaction with the new method, revealing that most students found the evaluation sheet and peer feedback to be effective. Within the limitations of this study, structured peer feedback using the evaluation sheet positively impacted grades pertaining to partial crown preparation, requiring less instructor feedback.

Quantitative Analysis of the Acceptance and Learning Success Instead of Flipped Classroom Teaching in a Caries Diagnosis Course for Undergraduate Students.

This pilot study aimed to investigate the effectiveness of a flipped classroom for undergraduate students in dentistry. The main objective was to compare the knowledge level of students before and after lectures and practice. All second-year dental students (n = 44) at Witten/Herdecke University participated in this pilot study. They took four knowledge assessments, i.e., T0: the baseline, T2a: after the online lecture (two weeks after T0), T2b: immediately after the face-to-face session, and T3: after the practical session (three weeks after T2). The students' satisfaction and self-assessment of their abilities were determined immediately after the practical session in an anonymous online questionnaire using LimeSurvey. To assess the level of knowledge, we used the Friedman and Wilcoxon-signed-rank tests with the Bonferroni correction to analyze the correct answer by comparing the results from different sessions. The students' satisfaction and self-assessment of their abilities were determined descriptively, presenting the mean and standard deviation. A significance level of p ≤ 0.05 was applied. Data from thirty-nine students regarding the level of knowledge were analyzed. There were statistically significant differences in the level of knowledge of the students at different times (p = 0.001). A total of 19.5% of students reported a problem with the flipped classroom method, and 80.5% reported no problem with this educational method. Ninety-four percent of students would like further flipped classrooms in dental education. Within the limitations of this pilot study, the results suggest that dental students benefit from the flipped classroom method and that this mode of education can be effective in introducing caries diagnosis education for undergraduate students.

In-vitro influence of the use of an erythritol powder through air polishing on the surface roughness and abrasiveness of various restorative materials.

The aim of this in-vitro study is to compare the prophylaxis powder Airflow® Plus to a conventional prophylaxis paste with regards to surface abrasion and roughness on four different restorative materials. A total of 80 samples were fabricated, including 20 of each investigated material. Among those were a nanocomposite (Ceram X Spectra™ ST, Dentsply), a glass ionomer cement (Ketac Fill™, 3M™), a cast metal alloy (Bio Maingold SG®, Heraeus Kulzer) and a ceramic (HeraCeram® Saphir, Heraeus Kulzer). Of each material, all samples were equally divided into two groups. Samples in one group were treated with AirFlow® Plus using the AirFlow® Prophylaxis Master (EMS, Switzerland) (Group AF) and the ones in the other group with Prophy Paste (Cleanic™, Kerr, Austria) (Group CL) on a rubber cup. Applied force amounted to 1.5 N at 2000 rpm. Under controlled reproduceable conditions, a 10-year interval with 4 application per year, a total of 200 seconds, was simulated. Size of each sample amounted to 6 mm in diameter and 2 mm in height. Half side of each sample were treated. While comparing the treated and untreated area of each sample, surface abrasion and roughness were measured using an optical 3D system. Roughness was measured based on the arithmetic roughness average of the surface (Ra) and root mean square of the surface roughness (Rq). The statistical evaluation of the data was carried out using the non-parametric Mann-Whitney-U-test, Wilcoxon-test and the Kruskal-Wallis test for group comparisons. In conclusion, the use of the rubber cup with Prophy Paste caused a significantly higher abrasion on composite, ceramic and gold compared to the AirFlow® Plus powder (p < 0.05). In group AF, the significant highest values for Ra were determined on GIC, followed by composite, gold and then ceramic in intragroup comparison. Ra on GIC was significantly higher in group AF (p < 0.05).

Comparative in vitro study of the cleaning efficacy of AirFloss ultra and I-Prox Sulcus brushes in an orthodontic phantom model.

Preventing biofilm-related risks such as gingivitis and white spot lesions during orthodontic treatments is very challenging. The cleaning efficiencies of AirFloss Ultra and I-Prox P sulcus brushes were evaluated using an orthodontic phantom model. After attaching brackets onto black-coated maxillary KaVo teeth, a plaque substitute was applied. The evaluated tooth surfaces were divided into two areas. Cleaning was performed with an AirFloss Ultra with two (A-2) or four (A-4) sprays or an I-Prox P for two (I-2) or four (I-4) seconds. Images before and after cleaning were digitally subtracted, and the percentage of fully cleaned surfaces was determined (Adobe Photoshop CS5, ImageJ). Statistical analysis was performed by ANOVA and post hoc tests with Bonferroni correction (SPSS 25, p < 0.05). The mean values of total cleaning efficacy were 26.87% for I-2, 43.73% for I-4, 34.93%, for A-2 and 56.78% for A-4. The efficacy was significantly higher for A-4 than for A-2, I-4, and I-2. There were significant differences between the four groups. Repeated cleaning led to an improved result. Within the study limitations, the AirFloss Ultra with four sprays proved to be more efficient than the sulcus brush I-Prox P for cleaning.

Clinical Study on the Effectiveness of Three Products in the Treatment of Herpes Simplex Labialis.

Herpes simplex labialis (HSL) is a viral disease that affects the perioral region. No guidelines recommending an effective treatment exist. The treatment of HSL with three different products was examined. Herpatch Serum, a film-forming patch, was compared to Compeed Patches, a set of semiocclusive hydrocolloid patches, and Zovirax Cream (ingredient: 5% acyclovir). In this prospective, randomized, examiner-blind study, 180 patients with recurrent HSL were split into three groups (Compeed: n = 60, Herpatch: n = 60, Zovirax: n = 60) and examined within 24 hours of HSL outbreak (DRKS Registration No.: DRKS00007786). The primary endpoint was healing time. The secondary endpoints were the reaction rate and quality of therapy evaluated by the Clinician's Global Assessment of Therapy (CGAT) and the Subject's Global Assessment of Therapy (SGAT) (0 = no response; 10 = excellent response), respectively. There was no significant difference among the healing times for the different products. The mean (95% confidence interval) was 9.67 days (9.11-10.22) for Compeed, 9.30 days (8.75-9.85) for Herpatch, and 9.80 days (9.30-10.30) for Zovirax. The reaction rate and quality of therapy (CGAT and SGAT) of Herpatch were significantly higher than those of Compeed and Zovirax. Within the study limitations, Herpatch proved to be an effective, non-antiviral alternative in the treatment of HSL.

Depth of acid penetration and enamel surface roughness associated with different methods of interproximal enamel reduction.

OBJECTIVES: To assess and compare the enamel surface quality after interproximal enamel reduction (IPR) was performed with different systems and to study the relation between acid penetration depth and enamel surface quality as well as the importance of remineralization. METHODS: Sixty-five extracted teeth were randomly allocated to five experimental groups: untreated control, manual with New Metal Strips, mechanical with oscillating segment (OS) discs, Safe-Tipped Bur Kit, and the Ortho-Strip, followed by 30 s of polishing with the Softflex system and the Compo-system after treating the tooth with OS discs. Mesial surfaces were demineralized for 24 h and distal surfaces were subjected to interchanging demineralization and remineralization cycles of 24 h each for 18 days. The analysis was carried out by profilometry, scanning electron microscopy, and polarization microscopy. RESULTS: After IPR and polishing, enamel roughness was reduced for all systems tested except for the Essix Safe-Tipped Bur Kit. Subsequent demineralization increased enamel roughness in all groups except controls beyond the original level prior to IPR except for IPR with New Metal Strips or Ortho-Strips and subsequent polishing. Cyclic demineralization and remineralization for 18 days yielded a reduction in acid penetration depth and an increase in surface smoothness, which correlated with each other only for controls and treatment with New Metal Strips or Ortho-Strips. CONCLUSIONS: Manual IPR, using New Metal Strips and, even more, the oscillating IPR system Ortho-Strips, yielded smoother interproximal enamel surfaces and less acid penetration depth than the IPR systems with OS discs and the Safe-Tipped Bur Kit after polishing and 18 days of cyclic demineralization and remineralization. Irrespective of the IPR procedure, proper remineralization of IPR-treated surfaces is advisable to reduce caries susceptibility.

Conformity, reliability and validity of digital dental models created by clinical intraoral scanning and extraoral plaster model digitization workflows.

BACKGROUND: In dentistry, digitization of dental arches with intraoral scanners could one day replace impressions and plaster model digitization processes, if accuracy is clinically sufficient. This study aimed to assess the reliability, validity and conformity of an intraoral scanning procedure (Lythos©, Ormco) and of two extraoral digitization workflows via alginate impression and plaster model scanning with the D810© (3shape) or the Atos II Triple Scan© (GOM) under clinical conditions. METHODS: In 20 subjects three consecutive intraoral scans, three alginate and one reference polyether impression were taken of both the upper and lower dental arch, respectively. The digital models created from the corresponding plaster models and the intraoral scans were superimposed with the polyether reference standard by both a global and a local best-fit algorithm. Reliability, validity and conformity of the three digital workflows were assessed via intraclass (ICC) and Lin's concordance correlation coefficients (CCC) as well as analyses according to Bland-Altman. RESULTS: The digital models created from the intraoral scanning procedure were less in agreement with the polyether reference (validity) than those from the extraoral procedures with reduced conformity and reliability. Local numerical deviations from the reference standard were approximately twice as high compared to the extraoral procedures, which showed high conformity and were equivalent and clinically acceptable in terms of reliability and validity. CONCLUSIONS: Although the intraoral scanning method with Lythos© seems to have drawbacks in terms of reliability, validity and conformity to the indirect alginate methods, all procedures proved to be clinically equivalent for diagnostic purposes.

Effectiveness of a new non-hydrogen peroxide bleaching agent after single use - a double-blind placebo-controlled short-term study.

INTRODUCTION: Tooth whitening represents perhaps the most common aesthetic procedure in dentistry worldwide. The efficacy of bleaching depends on three aspects: bleaching agent, bleaching method, and tooth color. OBJECTIVE: This in vivo study aimed to examine whitening effects on frontal teeth of the upper and lower jaws using an over-the-counter (OTC) non-hydrogen peroxide bleaching agent in comparison to a placebo after one single use. MATERIAL AND METHODS: Forty subjects (25 female; 15 male) participated in this double-blind randomized placebo-controlled trial. The subjects were randomly allocated to two groups (n=20). The test group received the OTC product (iWhite Instant) and the placebo group received an identically composed product except for the active agents. Each subject was treated with a prefilled tray containing iWhite Instant or the placebo for 20 minutes. The tooth shade of the front teeth (upper and lower jaws) was assessed before (E_0), immediately after (E_1) and 24 h after treatment (E_2), using a shade guide (VITA classical). Statistical testing was accomplished using the Mann-Whitney U test (p<0.001). The dropout rate was 0%. RESULTS: There were no significant differences at E_0 between placebo and test groups regarding the tooth color. Differences in tooth color changes immediately after (ΔE1_0) and 24 h after treatment (ΔE2_0) were calculated for both groups. The mean values (standard deviations) of tooth color changes for ΔE1_0 were 2.26 (0.92) in the test group and 0.01 (0.21) in the placebo group. The color changes for ΔE2_0 showed mean values of 2.15 (1.10) in the test group and 0.07 (0.35) in the placebo group. For ΔE1_0 and ΔE2_0 significant differences were found between the groups. CONCLUSION: In this short-term study, the results showed that a non-hydrogen peroxide bleaching agent has significant whitening effects immediately and 24 h after a single-use treatment.

Effectiveness of a new non-hydrogen peroxide bleaching agent after single use - a double-blind placebo-controlled short-term study

Abstract Tooth whitening represents perhaps the most common aesthetic procedure in dentistry worldwide. The efficacy of bleaching depends on three aspects: bleaching agent, bleaching method, and tooth color. Objective: This in vivo study aimed to examine whitening effects on frontal teeth of the upper and lower jaws using an over-the-counter (OTC) non-hydrogen peroxide bleaching agent in comparison to a placebo after one single use. Material and methods: Forty subjects (25 female; 15 male) participated in this double-blind randomized placebo-controlled trial. The subjects were randomly allocated to two groups (n=20). The test group received the OTC product (iWhite Instant) and the placebo group received an identically composed product except for the active agents. Each subject was treated with a prefilled tray containing iWhite Instant or the placebo for 20 minutes. The tooth shade of the front teeth (upper and lower jaws) was assessed before (E_0), immediately after (E_1) and 24 h after treatment (E_2), using a shade guide (VITA classical). Statistical testing was accomplished using the Mann-Whitney U test (p<0.001). The dropout rate was 0%. Results: There were no significant differences at E_0 between placebo and test groups regarding the tooth color. Differences in tooth color changes immediately after (ΔE1_0) and 24 h after treatment (ΔE2_0) were calculated for both groups. The mean values (standard deviations) of tooth color changes for ΔE1_0 were 2.26 (0.92) in the test group and 0.01 (0.21) in the placebo group. The color changes for ΔE2_0 showed mean values of 2.15 (1.10) in the test group and 0.07 (0.35) in the placebo group. For ΔE1_0 and ΔE2_0 significant differences were found between the groups. Conclusion: In this short-term study, the results showed that a non-hydrogen peroxide bleaching agent has significant whitening effects immediately and 24 h after a single-use treatment.

Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement.

OBJECTIVE: The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces. METHODS: Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05). RESULTS: The mean (standard deviation) surface loss was 21.03 (±1.26) µm for the sonic toothbrush, 15.71 (±0.85) µm for the oscillating-rotating toothbrush, 6.13 (±1.24) µm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) µm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05. CONCLUSION: Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5-year simulation.

Anterior Open Bite In 27 Months Old Children after Use of a Novel Pacifier - A Cohort Study.

OBJECTIVES: The aim of the present cohort study was to evaluate the influence of a novel pacifier on the first formation of malocclusion, the anterior open bite in children. STUDY DESIGN: 129 newborn children whose parents had decided to use pacifiers were randomly attributed to two experimental groups (D=Dentistar, n=56, Novatex, Pattensen, Germany; N=NUK, n=73, Mapa, Zeven, Germany). Children (n=42) who did not use a pacifier were not randomized and served as reference (C). Primary outcome was the presence of anterior open bite. It was hypothesized that D would result in lower incidence when compared to N. At the age of 27 months the children were examined with respect to anterior open bite. Fisher's exact test served to detect significant differences between groups D and N (SPSS 22.0). RESULTS: 121 children with a mean age of 26.7 months were included in the final analysis (D: n=45; N: n=42; C: n=34). In group D three children (6.7%) showed an anterior open bite. The respective values were 21 (50.0%) for N and 0 for C. The results for group D compared to N were significantly different (chi(2)-test, p<0.001). CONCLUSION: In comparison to a commonly used pacifier the novel one causes significantly less anterior open bites.

Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin--An In Vitro Study.

AIM: The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin. MATERIALS AND METHODS: Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis. RESULTS: With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group. CONCLUSIONS: Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions.

Investigation of the oral status and microorganisms in children with phenylketonuria and type 1 diabetes.

OBJECTIVE: The aim of this study was to investigate the oral parameters that influence the caries risk and risk of developing periodontal disease in children with phenylketonuria (PKU) and type 1 diabetes compared to healthy children. MATERIAL AND METHODS: Two hundred and thirty-eight children between the ages of 3 and 18 years were recruited in the PKU, diabetes and healthy group. The decayed, missing and filled surfaces (dmfs/DMFS) index, papillary bleeding index (PBI) and the Silness & Löe Index were assessed. Quantitative real-time polymerase chain reaction (PCR) was used for the detection of Streptococcus mutans (Sm), Lactobacillus casei (Lca), Lactobacillus species (Lac), Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannerella forsythensis (Tf). RESULTS: A statistically significant difference in the dmfs index value was found between the three groups. The mean dmfs index value for the PKU children (4.18) was found to be relatively high. Comparing the three groups, diabetics showed statistically significant higher values for the Silness and Löe Index. Comparing the diabetics to just the healthy children, the diabetics revealed a small statistically significant difference in the PBI score. A statistically significant difference was found between Lac, Lca and Pg in the three groups. Counts of Lac were the lowest in the PKU children. The diabetics showed the highest counts of Lca but lowest for Pg. CONCLUSIONS: Comparing the three groups, children with PKU revealed a higher caries experience in their primary dentition. While the diabetic children showed a lower one in their primary dentition, they were found to possess a slightly higher risk of developing periodontal disease. CLINICAL RELEVANCE: It is proposed that both groups of child patients be encouraged to seek early dental advice and be incorporated in a meticulous prevention programme.

Effect of 10% fluoride on the remineralization of dentin in situ

ABSTRACT Objective The purpose of this randomized, cross-over, in situ study was to determine the remineralization of demineralized dentin specimens after the application of a 10% fluoride (F-) or a 1% chlorhexidine–1% thymol (CHX–thymol) varnish. Material and Methods Twelve individuals without current caries activity wore removable appliances in the lower jaw for a period of four weeks. Each appliance contained four human demineralized dentin specimens fixed on the buccal aspects. The dentin specimens were obtained from the cervical regions of extracted human third molars. After demineralization, half the surface of each specimen was covered with a nail varnish to serve as the reference surface. The dentin specimens were randomly assigned to one of the three groups: F-, CHX–thymol, and control (no treatment). Before the first treatment period and between the others, there were washout periods of one week. After each treatment phase, the changes in mineral content (vol% µm) and the lesion depths (µm) of the dentin slabs were determined by transverse microradiography (TMR). Data analysis was accomplished by the Kruskal-Wallis test and the Mann-Whitney U test (p<0.05). Results The medians (25th/75th percentile) of integrated mineral loss were 312.70 (203.0-628.7) for chlorhexidine varnish, 309.5 (109.8-665.8) for fluoride varnish, and -346.9 (-128.7 - -596.0) for the control group. The medians (25th/75th percentile) of lesion depth were 13.6 (5.7-34.5) for chlorhexidine varnish, 16.5 (5.6-38.1) for fluoride varnish, and -14.2 (-4.5- -32.9) for the control group. Use of the 10% F- or 1% CHX–1% thymol varnishes resulted in significantly decreased mineral loss and lesion depth in dentin when compared with the control group. There were no statistically significant differences among the test groups. Conclusions Within the limitations of this study, the results suggest that the effect of the treatment of demineralized dentin with 10% F- or 1% CHX–1% thymol is better than without any treatment.

Influence of various acidic beverages on tooth erosion. Evaluation by a new method.

MATERIAL & METHODS: We have analyzed the loss of enamel and dentine after exposure to different non-alcoholic drinks with a simple new method using bovine teeth. 100 enamel and 100 dentine specimens from freshly extracted bovine incisors were randomly attributed to 10 groups (n=10 for enamel and dentine each). Prior to the start of the experiment all specimens were weighed using a precision balance. The mean initial masses (SD) were 35.8 mg (7.2) for enamel and 24.7 mg (7.0) for dentine. No statistically significant differences were found between groups for initial masses (p>0.05, ANOVA with Bonferroni post hoc test). Thereafter, all specimens of one group were simultaneously placed in 200 ml of the following fluids: Coca-Cola, Coca-Cola light, Sprite, apple juice, Red Bull, orange juice, Bonaqua Fruits (Mango-Acai), tap water, chlorinated swimming pool water, and lemon juice. Fluids were continuously ventilated at 37° C for 7 days. Thereafter the specimens were weighed again and the mean mass loss was calculated. RESULTS: The values were (enamel/dentine): Coca-Cola 7.5 mg/6.6 mg; Coca-Cola light 5.2 mg/3.5 mg, Sprite 26.1 mg/17.7 mg, apple juice 27.1 mg/15.2 mg, Red Bull 16.6 mg/17.0 mg, orange juice 24.3 mg/20.2 mg, Bonaqua Fruits (Mango-Acai) 17.8 mg/16.2 mg, tap water -0.2 mg/-0.3 mg, swimming pool water -0.3 mg/-0.2 mg, and lemon juice 32.0 mg/28.3 mg. From all drinks, Cola and Cola light showed the least erosivity (p<0.001, ANOVA with Bonferroni post hoc test) whereas lemon juice showed statistically significant higher erosivity than all other drinks except Sprite and apple juice (p<0.01, ANOVA with Bonferroni post hoc test). CONCLUSIONS: In conclusion, erosivity of common non-alcoholic drinks varies widely. For example, Sprite, apple juice, and orange juice are about five times more erosive than Coca-Cola light. The findings from the present study should be taken into account in choosing a diet that provides satisfactory nutrition while minimizing tooth erosion.

Effect of 10% fluoride on the remineralization of dentin in situ.

Objective The purpose of this randomized, cross-over, in situ study was to determine the remineralization of demineralized dentin specimens after the application of a 10% fluoride (F-) or a 1% chlorhexidine-1% thymol (CHX-thymol) varnish. Material and Methods Twelve individuals without current caries activity wore removable appliances in the lower jaw for a period of four weeks. Each appliance contained four human demineralized dentin specimens fixed on the buccal aspects. The dentin specimens were obtained from the cervical regions of extracted human third molars. After demineralization, half the surface of each specimen was covered with a nail varnish to serve as the reference surface. The dentin specimens were randomly assigned to one of the three groups: F-, CHX-thymol, and control (no treatment). Before the first treatment period and between the others, there were washout periods of one week. After each treatment phase, the changes in mineral content (vol% µm) and the lesion depths (µm) of the dentin slabs were determined by transverse microradiography (TMR). Data analysis was accomplished by the Kruskal-Wallis test and the Mann-Whitney U test (p<0.05). Results The medians (25th/75th percentile) of integrated mineral loss were 312.70 (203.0-628.7) for chlorhexidine varnish, 309.5 (109.8-665.8) for fluoride varnish, and -346.9 (-128.7 - -596.0) for the control group. The medians (25th/75th percentile) of lesion depth were 13.6 (5.7-34.5) for chlorhexidine varnish, 16.5 (5.6-38.1) for fluoride varnish, and -14.2 (-4.5- -32.9) for the control group. Use of the 10% F- or 1% CHX-1% thymol varnishes resulted in significantly decreased mineral loss and lesion depth in dentin when compared with the control group. There were no statistically significant differences among the test groups. Conclusions Within the limitations of this study, the results suggest that the effect of the treatment of demineralized dentin with 10% F- or 1% CHX-1% thymol is better than without any treatment.

Efficacy of a novel pacifier in the prevention of anterior open bite.

PURPOSE: The purpose of this study was to test a novel pacifier (Dentistar) regarding the development of anterior open bite in infants. METHODS: One hundred twenty-nine newborn children were randomly assigned to 2 experimental groups: NUK (N; N =73); and Dentistar (D; N=56. Children (N=42) who did not use a pacifier served as the control (C). At 10- to 26-months old, the children were re-examined (via a blind operator) regarding the existence of an anterior open bite. RESULTS: One hundred twenty-one toddlers (66 females, 55 males) were included in the final analysis (N: N=42; D: N=43; C: N=36). The mean age was 15.9 (±3.9 SD) months. In Group N, 16 children (38%) showed an anterior open bite, 2 (5%) in Group D, and 0 in Group C. The incidence of open bites was significantly less in Groups D and C vs N (chi-square test, P<.001). No significant difference was found between D and C. CONCLUSION: Pacifier use may promote open bites in 16-month-old infants. Compared to a commonly used pacifier, the Dentistar caused almost no anterior open bites and, therefore, can be recommended for children younger than 16 months old.

Cleaning efficacy and soft tissue trauma after use of manual toothbrushes with different bristle stiffness.

BACKGROUND: The purpose of this study is to evaluate the efficacy of manual toothbrushes of the same type with different bristle stiffness concerning plaque removal, gingivitis development, and soft tissue trauma. METHODS: In a randomized controlled trial, three groups with 40 subjects each used manual toothbrushes with either hard-, medium-, or soft-bristle stiffness. The at-home brushing time was set for 2 minutes, twice a day. Four and 8 weeks after the baseline examination, clinical parameters for plaque removal, gingivitis, and soft tissue damage were recorded again. Recruitment and examinations of the subjects were performed at the Department of Operative and Preventive Dentistry and Endodontics, Heinrich Heine University. A total of 120 volunteers (age range: 18 to 62 years) were recruited and stratified according to sex and age. Primary outcome measures were differences in the Quigley and Hein index (QHI) and papillary bleeding index (PBI) compared to baseline; secondary outcome measures were differences in the modified approximal plaque index (MAPI) and Danser gingival abrasion index. RESULTS: The QHI and MAPI showed lower index scores in subjects who used hard-bristled toothbrushes after 8 weeks (P <0.05 and P <0.001, respectively). In contrast, subjects who used toothbrushes with hard bristles demonstrated more gingival lesions (P <0.01) and higher PBI scores after 4 and 8 weeks (P <0.001) compared to subjects who used soft- or medium-bristled toothbrushes. CONCLUSION: Manual toothbrushes with hard bristles may better remove plaque, but may also cause more soft tissue trauma compared to brushes with softer bristles.

Restoring strength of incisors with veneers and full ceramic crowns.

PURPOSE: The aim was to determine the in vitro fracture resistance of incisors restored with veneers and full ceramic crowns compared to unrestored teeth. MATERIALS AND METHODS: Seventy intact, extracted human maxillary central incisors were randomized and assigned to 7 groups (n = 10). The teeth in group 1 remained intact (control). The teeth in groups 2 to 6 were prepared and IPS Empress restorations were conditioned and bonded using an adhesive luting cement, Variolink II/Syntac (group 2: labial veneer with incisal overlap, group 3: 3/4 veneer with margin in enamel, group 4: 3/4 veneer with margin in dentin, group 5: crown with margin in enamel, group 6: crown with margin in dentin group 7: veneer on worn tooth. After finishing and polishing, specimens were stored in water and thermocycled for 2000 cycles between 5 degrees C and 55 degrees C. The maximal fracture load of the specimens (40-degree inclination) was determined using the universal testing machine (Zwick) at a constant crosshead speed (0.5 mm/min). The statistical analysis was performed using the Kruskal-Wallis test with Bonferroni correction (p < 0.05). Fracture surfaces were qualitatively analyzed by SEM. RESULTS: All restored teeth with cervical preparation margins in enamel showed a fracture load not significantly different from the intact teeth (control). Restored teeth with cervical preparation margins in dentin showed a significantly lower fracture load. All restorations showed a fracture load far above 400 N, serving as functional reference for anterior teeth. The failures were predominantly cohesive. CONCLUSION: For the restoration of tooth strength, defining the finishing lines of veneers and crowns in enamel is recommended. Restorations with finishing lines in dentin resulted in significant loss of strength. Three-quarter veneers with finishing lines in enamel are functionally equal to crowns with the advantage of conserving tooth structure.

Comparative clinical study of the effectiveness of three different bleaching methods.

OBJECTIVE: The current study assessed the efficacy of three current bleaching methods. METHODS: Seventy-five healthy subjects (45 female; 30 male) with anterior teeth, having a Vita Shade score of A2 or darker, participated in the study. The subjects were randomly assigned to one of three treatment groups: Group A: home-bleaching (illumine Home, 10% carbamide peroxide, trays, overnight, for two weeks), Group B: in-office bleaching (Illumine Office, 15% hydrogen peroxide, trays for 45 minutes, three times over three weeks), Group C: Whitestrips (strips, twice a day, 30 minutes each for two weeks). Following the screening visit, three weeks prior to the baseline examination, all subjects received a dental prophylaxis. The color of the teeth was determined using a colorimeter (ShadeEye NCC) and a custom-made stent at baseline (E0), immediately after completion of the bleaching (E3) and three months after treatment (E4). All subjects received oral hygiene instructions and a toothbrush and toothpaste for oral home care during the study period. The change of tooth color was determined for each treatment regimen between baseline and E3 and baseline and E4 and was statistically analyzed performing the Kruskal Wallis test and the Mann-Whitney-U test. The significance level was set atp < 0.01. RESULTS: The dropout rate was 0%. Mean (SD) deltaE* (overall color change) from baseline to immediately after treatment was 6.57 (2.13) for Group A, 5.77 (1.72) for Group B and 3.58 (1.57) for Group C. The mean (SD) tooth color change from baseline to three months after treatment deltaE* was: 4.98 (1.34) for Group A, 4.59 (1.42) for Group B and 2.99 (1.39) for Group C. Significant differences were found between home bleaching and Whitestrips, as well as between in-office bleaching and Whitestrips, but not between home-bleaching and in-office bleaching during the same time. CONCLUSION: Using an objective color measurement device, home bleaching and in-office bleaching were found to be superior to Whitestrips. Home bleaching and in-office bleaching were equally efficient for bleaching teeth and maintaining the results for up to three months.