Wolfgang H.-M. Raab

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.

The early history of the transmissible spongiform encephalopathies exemplified by scrapie

Transmissible spongiform encephalopathies (TSE) is a group of diseases that is unique in comprising disorders that can occur sporadically, are hereditary and/or infectious. The transmissible pathogen--the prion--is distinct from all other pathogens in being devoid of nucleic acids. During the elucidation of these disorders, many different--and contradictory--theories have been put forward. Early researchers, mostly driven by the economic impact of these diseases on sheep farming, engaged in heavy disputes concerning heredity vs. infectivity of scrapie. Following the experimental demonstration of scrapies infectivity during the 20th century, research focused on the characterization of the nature of the transmissible agent. The current work comprehensively summarizes the available early literature on TSE research. A review of the historical literature is presented, describing the efforts in breeding, transmission experiments, and theories about the nature of the infectious agent.

In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects

STATEMENT OF PROBLEM Occlusal load has frequently been suggested to be involved in the development of a noncarious cervical lesion (NCL). However, there is a lack of clinical studies evaluating NCLs and occlusal parameters in sleep bruxism (SB) subjects. PURPOSE The purpose of this clinical study was to assess the frequency of NCLs and determine potential occlusal differences between SB subjects and healthy control subjects. MATERIAL AND METHODS A total of 91 volunteers, 58 women and 33 men, with a mean (SD) age of 28.37 (4.89) years (range of 20 to 39 years), participated in this investigation. The clinical assessment of SB was based on the criteria of the American Academy of Sleep Medicine. The participants were divided into 2 groups; 58 subjects were assigned to the SB group and 33 subjects to the control group, following a thorough dental examination that was performed by a single trained dentist. Additionally, the following parameters were recorded: mean number of teeth present, existence/absence of NCLs, frequency of NCLs relating to the type of tooth, type of occlusal guidance scheme, existence of a slide from centric occlusion (CO) to maximum intercuspation (MI), length of the slide, and report of tooth hypersensitivity. Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (alpha=.05). RESULTS NCLs were significantly more prevalent in SB subjects (39.7%) than in the control subjects (12.1%) (P=.006). In SB subjects, the first premolars were the teeth most affected, and in control subjects, the first molars were most affected. Tooth hypersensitivity was reported in 62.1% of the SB subjects and in 36.4% of the control subjects (P=.018). The evaluation of occlusal guidance schemes revealed no significant difference between the groups. In SB subjects (70.7%), a slide from CO to MI was significantly more prevalent than in control subjects (42.4%) (P=.008). Moreover, SB subjects demonstrated a significantly longer mean (SD) slide of 0.77 (0.69) mm compared to that of control subjects of 0.4 (0.57) mm (P=.008). CONCLUSIONS Within the limitations of this study, SB subjects demonstrated significantly more NCLs than the control group; whereas, the type of occlusal guidance scheme seems to be of minor importance in the development of NCLs.

Impact of replacing Bis-GMA and TEGDMA by other commercially available monomers on the properties of resin-based composites

PURPOSE To evaluate important material properties of six experimental resin-based restorative materials (EXP) with systematically modified resin matrices using conventional and alternative monomers in comparison with an experimental standard (ST). MATERIALS AND METHODS Commercially available monomers were selected according to their molecular weight, functionality, viscosity, and polymerization shrinkage. ST, 71wt% filler, matrix UDMA/Bis-GMA/TTEGDMA and six EXPs with modified organic matrices but the same filler content were manufactured. Flexural strength, flexural modulus, water sorption, solubility and polymerization shrinkage of all EXPs were measured and compared with the results of ST. RESULTS ANOVA (p<0.05) revealed significant differences among the materials and all investigated properties. Bis-GMA and UDMA were substituted by alternative monomers without losing flexural strength or modulus. Replacing the diluting monomer TTEGDMA with alternative monomers resulted in increased flexural strength. None of the experimental products with modified matrices showed increased water sorption or solubility but some even performed better than ST. Increased hygroscopic expansion and reduced shrinkage were achieved using a very hydrophilic monomer but no significant differences of water sorption and solubility in comparison with ST were found. CONCLUSION The results indicated that there are monomers commercially available providing the same or even better properties than conventional matrices.

Association between oral health‐related and general health‐related quality of life in subjects attending dental offices in Germany

OBJECTIVES To evaluate the GHRQoL and OHRQoL of patients attending dental offices in Germany and to determine correlation coefficients between SF (Short Form)-12 and OHIP (Oral Health Impact Profile)-14 scores. METHODS A total of 10,342 dental offices were randomly selected. Each of the 1,113 that consented to participate received 20 questionnaires to be filled in by a convenience sample of the patients. The questionnaire included the OHIP-14-form for OHRQoL as well as the SF-12-form for GHRQoL. RESULTS A total of 12,392 completed questionnaires were analyzed. The mean age of the participants (64.9 percent female, 35.1 percent male) was 44.25 years. The mean summary score of OHIP-14 was 6.30 (SD 7.46). The mean physical component summary scale (PCS) of the SF-12 was 51.15 (SD 7.23) and the mental component summary scale (MCS) was 50.17 (SD 8.55). The variance of PCS and MCS could be explained to 10 percent each by oral health-related quality of life (r2 = 0.095 and 0.101, P < 0.001). CONCLUSION OHRQoL is considerably related to GHRQoL.

Novel nano-particles as fillers for an experimental resin-based restorative material

The purpose of this study is to compare the properties of two experimental materials, nano-material (Nano) and Microhybrid, and two trade products, Clearfil AP-X and Filtek Supreme XT. The flexural strength and modulus after 24h water storage and 5000 thermocycles, water sorption, solubility and X-ray opacity were determined according to ISO 4049. The volumetric behavior (DeltaV) after curing and after water storage was investigated with the Archimedes principle. ANOVA was calculated with p<0.05. Clearfil AP-X showed the highest flexural strength (154+/-14 MPa) and flexural modulus (11,600+/-550 MPa) prior to and after thermocycling (117+/-14 MPa and 13,000+/-300 MPa). The flexural strength of all materials decreased after thermocycling, but the flexural modulus decreased only for Filtek Supreme XT. After thermocycling, there were no significant differences in flexural strength and modulus between Filtek Supreme XT, Microhybrid and Nano. Clearfil AP-X had the lowest water sorption (22+/-1.1 microg mm(-3)) and Nano had the highest water sorption (82+/-2.6 microg mm(-3)) and solubility (27+/-2.9 microg mm(-3)) of all the materials. No significant differences occurred between the solubility of Clearfil AP-X, Filtek Supreme XT and Microhybrid. Microhybrid and Nano provided the highest X-ray opacity. Owing to the lower filler content, Nano showed higher shrinkage than the commercial materials. Nano had the highest expansion after water storage. After thermocycling, Nano performed as well as Filtek Supreme XT for flexural strength, even better for X-ray opacity but significantly worse for flexural modulus, water sorption and solubility. The performances of microhybrids were superior to those of the nano-materials.

Maladaptive coping strategies in patients with bruxism compared to non-bruxing controls.

Background: Sleep bruxism is the non-functional grinding or clenching of teeth during sleep. It may lead to tooth damage and myofascial pain. Although stress is discussed as a main causal agent, there is a lack of studies concerning coping strategies in patients with sleep bruxism. Purpose: The aim of the present study was to investigate whether bruxers, compared to non-bruxing individuals, apply maladaptive coping strategies. Method: Seventy-five sleep bruxers and 38 non-bruxers were selected by dental examination and tested by a German coping questionnaire (SVF78). Results: A significant difference in positive coping strategies was observed between the two groups. Bruxers reported less positive coping strategies, mainly less “reaction control” and “positive self-instructions.” In general, males reported less negative coping strategies. Conclusion: The reported effects demonstrate a deficit of functional coping strategies in bruxers, whereas strategies that enhance stress do not seem to be associated with sleep bruxism. Findings do not admit the conclusion that there is a causal association of maladaptive coping and bruxism. However, they support the approach of a multidisciplinary therapy involving psychological treatment.

A new approach to influence contact angle and surface free energy of resin-based dental restorative materials

The purpose of the present study was to identify novel delivery systems and active agents which increase the water contact angle and reduce the surface free energy when added to resin-based dental restorative materials. Two delivery systems based on zeolite or novel polymeric hollow beads (Poly-Pore), loaded with two low surface tension active agents (hydroxy functional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate) were used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as a standard (ST). Flexural strength, flexural modulus, water sorption, solubility, polymerization shrinkage, surface roughness Ra, contact angle θ, total surface free energy γS, and the apolar γSLW, polar γSAB, Lewis acid γS+ and base γS- components, and the active agents surface tensions γL were determined (P<0.05). The active agents did not differ in γL. The modified materials had significantly higher θ but significantly lower γS, γSAB and γS- than the ST. A Poly-Pore/polydimethyl siloxane delivery system yielded the highest θ (110.9±3.5°) acceptable physical properties and the lowest values for γSLW and γS-. Among the modified materials the polymerizable materials containing active agents had the lowest γAB and the highest γS+ and γS-. Although not significant, both of the zeolite delivery systems yielded higher γSLW, γS+ and γS- but lower γSAB than the Poly-Pore delivery systems. Poly-Pore based delivery systems highly loaded with low surface tension active agents were found not to influence the physical properties but to significantly increase the water contact angle and thus reduce surface free energy of dental resin composites.

Bacterial viability on surface-modified resin-based dental restorative materials

UNLABELLED The purpose of the present investigation was to investigate the viability of early colonizers on the surfaces of resin-based dental restorative materials modified with low-surface tension active agents in comparison with the unmodified material. A novel polymeric sorption material, loaded with two low-surface tension γ(L) active agents (hydroxyfunctional polydimethylsiloxane and polydimethylsiloxane) or a polymerizable active agent (silicone polyether acrylate), was used to modify commonly formulated experimental dental resin composites. The non-modified resin was used as the standard (ST). The viability of Actinomyces naeslundii, Actinomyces viscosus, Streptococcus mitis, Streptococcus oralis, and Streptococcus sanguinis on water-stored, polished, and human saliva pellicle-coated specimens was determined using a fluorescence microscope after 8 and 24h. Total, vital, and non-vital cells were calculated from the microscopic images by counting pixels per colour. Means, standard deviations, univariate ANOVA and multiple comparisons with post hoc Scheffés tests were calculated. t-Test was done to compare 8-h and 24-h bacteria counts. For all tests p<0.05 was chosen. NULL HYPOTHESIS the test materials and the standard did not differ either in the total bacterial counts or in the respective bacteriums viability after 8 or 24h. The test materials modified with the silicone polyether acrylate showed lower total bacteria count after 8 or 24h than ST. But all test materials had significantly fewer vital cells after 8 or 24h compared to ST. The contact angle did not influence bacterial adhesion, but low total SFE and a low polar term of SFE resulted in fewer bacteria. The materials chemistry also affected the total and vital cell counts. Different bacteria viabilities needed to be explored to obtain relevant information regarding bacterial adhesion on dental composite resins. The novel sorption material loaded with low γ(L) active agents or with a low γ(L) polymerizable silicone polyether acrylate used to modify the chemistry of the test materials was appropriate to reduce bacterial adhesion or cell viability, respectively.

Histone deacetylases 2 and 9 are coexpressed and nuclear localized in human molar odontoblasts in vivo

Histone deacetylases (HDACs) are components of nuclear multiprotein complexes that deacetylate histones and perform important roles in repression of transcription. Using specific rabbit mAbs, we analyzed by immunohistochemistry and confocal immunofluorescence analysis the expression and subcellular localization of HDAC1–4 and HDAC9 in sections of adult human third molars. HDAC2 and HDAC9 were expressed in some pulpal cells and strongly expressed in the majority of mature odontoblasts. In contrast, only weak expression of HDAC1, HDAC3 and HDAC4 was observed. Confocal immunofluorescence analysis together with the DNA stain DRAQ5 revealed that HDAC2 and HDAC9 were coexpressed within the odontoblast nucleus, but localized to distinct subnuclear structures. In contrast to the current point of view, HDAC2 is strongly expressed in a terminally differentiated cell type. Our results imply that class I and II HDACs are involved in the transcriptional regulation of human odontoblasts in vivo.