Quantification of tooth wear: Conventional vs new method using toolmakers microscope and a three-dimensional measuring technique

Objectives

This study aimed to evaluate the reliability of a new CAD-CAM Laser scanning machine in detection of incisal tooth wear through a 6-month period and to compare the accuracy of using this new machine against measuring tooth wear using tool maker microscope and conventional tooth wear index.

Methods

Twenty participants (11 males and 9 females, mean age = 22.7 years, SD = 2.0) were assessed for incisal tooth wear of lower anterior teeth using Smith and Knight clinical tooth wear index (TWI) on two occasions, the study baseline and 6 months later. Stone dies for each tooth were prepared and scanned using the CAD-CAM Laser Cercon System (Cercon Smart Ceramics, DeguDent, Germany). Scanned images were printed and examined under a toolmaker microscope (Stedall-Dowding Machine Tool Company, Optique et Mecanique de Precision, Marcel Aubert SA, Switzerland) to quantify tooth wear and then the dies were directly assessed under the microscope to measure tooth wear. The Wilcoxon Signed Ranks Test was used to analyse the data.

Results

TWI scores for incisal edges were 0, 1, and 2 and were similar at both occasions. Scores 3 and 4 were not detected. Wear values measured by directly assessing the dies under the tool maker microscope (range = 517–656 μm, mean = 582 μm, and SD = 50) were significantly more than those measured from the Cercon digital machine images (range = 132–193 μm, mean  = 165 μm, and SD = 27) and both showed significant differences between the two occasions.

Conclusions

Measuring images obtained with Cercon digital machine under tool maker microscope allowed detection of wear progression over the 6-month period. However, measuring the dies of worn dentition directly under the tool maker microscope enabled detection of wear progression more accurately. Conventional method was the least sensitive for tooth wear quantification and was unable to identify wear progression in most cases.     

Involvement of angiotensin II type 1 receptors in interleukin-1β-induced interleukin-6 production in human gingival fibroblasts

The renin-angiotensin system is thought to be involved in inflammatory processes such as periodontitis. However, its precise role is still unclear. Therefore, in the present study the expression of the angiotensin II type 1 receptor (AT1R) was investigated in inflamed human gingival tissue, and the possible involvement of the AT1R in interleukin-1β (IL-1β)-induced interleukin-6 (IL-6) production by cultured human gingival fibroblasts (HGFs) was also studied. Immunohistochemical staining revealed that inflammatory cells and fibroblast-like cells were positive for the AT1R. However, in healthy gingival tissue, AT1R staining was very weak. The levels of AT1R mRNA and AT1R protein increased in HGFs after stimulation with IL-1β. The levels of IL-1β-induced IL6 mRNA and IL-6 protein were significantly reduced in AT1R gene-silenced HGFs compared with control HGFs. The data suggest that the AT1R may be involved in the regulation of gingival inflammation by modulating IL-1β-induced IL-6 production in HGFs.     

TGF-β1 gene polymorphism in renal transplant patients with and without gingival overgrowth

Oral Diseases (2011) 17 , 414–419 Background: The incidence of gingival overgrowth among renal transplant patients treated with cyclosporine A ranges from 13% to 84.6%, and the overgrowth is not only esthetic but also a medical problem. We studied the determination of association between TGF‐β1 (TGFB1) gene polymorphism and gingival overgrowth in kidney transplant patients medicated with cyclosporin A. Methods: Eighty‐four kidney transplant patients with gingival overgrowth and 140 control transplant patients without overgrowth were enrolled into the case control study. TGFB1 polymorphism was determined using the PCR‐RFLP assay for +869T>C in codon 10 and +915G>C in codon 25 as well as TaqMan real‐time PCR assays for promoter ?800G>A and ?509C>T SNPs. Results: In kidney transplant patients suffering from gingival overgrowth, mean score of gingival overgrowth was 1.38 ± 0.60, whereas in control subjects it was 0.0. The patients with gingival overgrowth were characterized by similar distribution of TGFB1 genotypes and allele in comparison to subjects without gingival overgrowth. Among 16 potentially possible haplotypes of TGFB1 gene, only four were observed in the studied sample of kidney transplant patients: G_C_T_G, G_T_C_G, G_C_C_C, and A_C_T_G, with similar frequency in patients with and without gingival overgrowth. Conclusion: No association between the TGFB1 gene polymorphism and gingival overgrowth was revealed in kidney transplant patients administered cyclosporine A.     

In vivo evaluation of an oral health toothpaste with 0.1% vitamin E acetate and 0.5% sunflower oil (with vitamin F)

Objectives : To measure the delivery of active ingredients of a new oral health toothpaste with zinc citrate trihydrate/triclosan and containing α‐tocopherol acetate (vitamin E) and sunflower oil (vitamin F) and compare its anti‐plaque/anti‐ginigvitis efficacy to that of a clinically proven control toothpaste. Methods : The new toothpaste contained 0.1% vitamin E acetate (α‐tocopherol acetate) and 0.5% sunflower oil as a source for vitamin F (linoleic acid). It also included an anti‐caries agent (0.32% sodium fluoride) and a proven gum‐health active system (0.3% triclosan and 0.75% zinc citrate trihydrate). Three studies were carried out. In study 1 (n=45) the bio‐availability of zinc and triclosan was measured in plaque 12h after brushing with the test toothpaste. In study 2 (n=93) the effect of the test toothpaste on plaque and gingival condition was investigated over three weeks in a randomised, parallel, double‐blind, controlled design. The control toothpaste was a fluoride toothpaste containing 0.3% triclosan. Healthy adult volunteers with GI>1.0 were enrolled and given a full mouth scale and polish. Plaque levels (Modified Quigley and Hein Index) and gingival condition (Gingival Index) were assessed at baseline and after three weeks. Study 3 (n=93) lasted for nine weeks. Subjects did not receive a full mouth scale and polish at baseline but the study was otherwise identical to study 2. Results : In study 1, no triclosan was detected in baseline plaque samples; mean triclosan concentration in plaque 12h after last brushing with the test toothpaste was 5.78μg/g (std=4.74); the mean zinc concentration rose from 15.2μg/g zinc ion in baseline plaque samples to 84.3μg/g zinc ion (p>0.0001) in samples taken 12h after brushing. In study 2, mean plaque and gingival indices were significantly reduced in both test and control group after three weeks compared to baseline; there was no significant difference between the test and control group after three weeks. In study 3, mean plaque and gingival indices were significantly reduced in both test and control group after three and nine weeks compared to baseline; there was no significant difference between the test and control group after three and nine weeks. Conclusion : The delivery of zinc and triclosan from a new oral health toothpaste containing zinc citrate trihydrate and triclosan was unaffected by the addition of α‐tocopherol acetate (vitamin E) and sunflower oil (vitamin F). The new toothpaste was effective in reducing plaque levels and improving gingival conditions to the same degree as a clinically proven positive control. Regular oral hygiene with this toothpaste is therefore beneficial for maintaining healthy and strong gums.     

模型转化法建立磨牙及其牙周组织的三维有限元模型

目的建立下颌第二恒磨牙及其牙周膜、牙槽骨的分析用模型。方法应用CAE软件3D MAX6.0及CATIA4.0生成磨牙及其牙周组织的三维有限元模型,利用HYPERMESH划分网格,生成可分析的三维有限元实体模型。结果建立了下颌第二恒磨牙及其牙周膜、牙槽骨的三维有限元模型,可以分别进行受力状态下应力、应变的分析。结论该模型可供口腔正畸矫治中磨牙的受力分析应用。     

A reconstructed computerized tomographic comparison of Ni-Ti rotary GT files versus traditional instruments in canals shaped by novice operators

AIM: The aim of this study was to compare the effects of preparation with conventional stainless steel Flexofiles and Gates Glidden burs versus nickel-titanium GT rotary files in the shaping of mesial root canals of extracted mandibular molars. METHODOLOGY: A total of 54 canals from 27 mesial roots of mandibular molar teeth were prepared using one of two methods by novice dental students. One canal in each root was prepared by a crown-down approach. utilizing stainless steel Flexofiles and Gates Glidden burs. The other canal was prepared using nickel-titanium GT rotary files in a crown-down fashion as recommended by the manufacturer. Preoperative CT scans of each root were recorded and 50 canal specimens were available for postoperative comparisons. Following canal shaping, postoperative scans were superimposed on the original images. Changes in canal area, canal transportation and thickness of remaining root structure at strategic levels of the root were analyzed. The time taken for each method was also noted. RESULTS: At the coronal and mid-root coronal one-third sections, the rotary GT files produced a significantly smaller postoperative canal area (P < 0.05). In the mid-root sections there was significantly less transportation of the root canal toward the furcation, and less thinning of the root structure with GT files compared to the stainless steel files (P < 0.05). Overall, there was greater conservation of structure coronally and more adequate shape in the mid-root level. The GT rotary technique was significantly faster than the stainless steel hand-held file technique (P < 0.0001). Two GT instruments fractured during the study. CONCLUSIONS: Under the conditions of this study, novice dental students were able to prepare curved root canals with Ni-Ti GT rotary files with less transportation and greater conservation of tooth structure, compared to canals prepared with hand instruments. The rotary technique was significantly faster.     

Conflict control processing in adults with developmental dyslexia: An event related potentials study

ObjectiveThe present study investigated the time course for processing conflict in dyslexic adults using a flanker task.MethodsSixteen dyslexic and 15 control adults performed a flanker task comprising congruent and incongruent trials in which participants had to indicate the direction of targets surrounded by flankers. Early negative potentials associated with orienting of attention (i.e., N1) and conflict monitoring (i.e., N2) and two positive potentials associated with conflict resolution (i.e., P3b and Nogo P3) were recorded.ResultsThe behavioral data showed differences between incongruent and congruent trials for reaction times in both groups but for error rate only in dyslexics. As in previous studies, controls displayed greater N1, N2 and NoGo P3 as well as a smaller P3b in incongruent trials. Dyslexics lacked N1, N2 and P3b modulation whereas NoGo P3 effect was preserved.ConclusionDyslexics showed impairments in conflict monitoring and in some aspects of conflict resolution (i.e., the allocation of attentional resources) whereas other aspects of conflict resolution (i.e., the inhibition) were preserved.SignificanceThis is the first study to investigate conflict control processing in dyslexic adults using ERPs. Results provide evidence for deficits in orienting of attention, conflict monitoring and allocation of attentional resources in dyslexics.