A Novel Quantitative Method for Tooth Grinding Surface Assessment Using 3D Scanning

Sleep bruxism is an oral parafunction that involves involuntary tooth grinding and clenching. Splints with a colored layer that gets removed during tooth grinding are a common tool for the initial diagnosis of sleep bruxism. Currently, such splints are either assessed qualitatively or using 2D photographs, leading to a non-neglectable error due to the 3D nature of the dentition. In this study we propose a new and fast method for the quantitative assessment of tooth grinding surfaces using 3D scanning and mesh processing. We assessed our diagnostic method by producing 18 standardized splints with 8 grinding surfaces each, giving us a total of 144 surfaces. Moreover, each splint was scanned and analyzed five times. The accuracy and repeatability of our method was assessed by computing the intraclass correlation coefficient (ICC) as well reporting means and standard deviations of surface measurements for intra- and intersplint measurements. An ICC of 0.998 was computed as well as a maximum standard deviation of 0.63 mm2 for repeated measures, suggesting an appropriate accuracy of our proposed method. Overall, this study proposes an innovative, fast and cost effective method to support the initial diagnosis of sleep bruxism.

Understanding the Basis of METH Mouth Using a Rodent Model of Methamphetamine Injection, Sugar Consumption, and Streptococcus mutans Infection

ABSTRACT “METH mouth” is a common consequence of chronic methamphetamine (METH) use, resulting in tooth decay and painful oral tissue inflammation that can progress to complete tooth loss. METH reduces the amount of saliva in the mouth, promoting bacterial growth, tooth decay, and oral tissue damage. This oral condition is worsened by METH users’ compulsive behavior, including high rates of consumption of sugary drinks, recurrent tooth grinding, and a lack of frequent oral hygiene. Streptococcus mutans is a Gram-positive bacterium found in the oral cavity and associated with caries in humans. Hence, we developed a murine model of METH administration, sugar intake, and S. mutans infection to mimic METH mouth in humans and to investigate the impact of this drug on tooth colonization. We demonstrated that the combination of METH and sucrose stimulates S. mutans tooth adhesion, growth, and biofilm formation in vivo. METH and sucrose increased the expression of S. mutans glycosyltransferases and lactic acid production. Moreover, METH contributes to the low environmental pH and S. mutans sucrose metabolism, providing a plausible mechanism for bacterium-mediated tooth decay. Daily oral rinse treatment with chlorhexidine significantly reduces tooth colonization in METH- and sucrose-treated mice. Furthermore, human saliva inhibits S. mutans colonization and biofilm formation after exposure to either sucrose or the combination of METH and sucrose. These findings suggest that METH might increase the risk of microbial dental disease in users, information that may help in the development of effective public health strategies to deal with this scourge in our society. IMPORTANCE “METH mouth” is characterized by severe tooth decay and gum disease, which often causes teeth to break or fall out. METH users are also prone to colonization by cariogenic bacteria such as Streptococcus mutans. In addition, this oral condition is aggravated by METH users’ compulsive behavior, including the consumption of beverages with high sugar content, recurrent tooth grinding, and a lack of frequent oral hygiene. We investigated the effects of METH and sugar consumption on S. mutans biofilm formation and tooth colonization. Using a murine model of METH administration, sucrose ingestion, and oral infection, we found that the combination of METH and sucrose increases S. mutans adhesion and biofilm formation on the teeth of C57BL/6 mice. However, daily chlorhexidine-based oral rinse treatment reduces S. mutans tooth colonization. Similarly, METH has been associated with dry mouth or hyposalivation in users. Hence, we assessed the impact of human saliva on biofilm formation and demonstrated that surface preconditioning with saliva substantially reduces S. mutans biofilm formation. Our results are significant because to our knowledge, this is the first basic science study focused on elucidating the fundamentals of METH mouth using a rodent model of prolonged drug injection and S. mutans oral infection. Our findings may have important translational implications for the development of treatments for the management of METH mouth and more effective preventive public health strategies that can be applied to provide effective dental care for METH users in prisons, drug treatment centers, and health clinics.

Anomalous erosion patterns on the cheek teeth of babirusa (genus Babyrousa)

Two types of anomalous erosive wear, designated “Wear” and “Groove”, were found in the molar teeth of adult babirusa (genus Babyrousa Perry, 1811) species from Buru or the Sula Islands and Sulawesi, Indonesia. A survey of 590 specimens of babirusa crania and mandibles from international museums and private collections revealed their presence in 20 of 187 specimens from Buru or the Sula Islands, in 99 of 391 specimens from Sulawesi, and in 4 of 31 subfossil specimens from South Sulawesi. “N_Wear” comprised a discrete indentation or almost circular erosion of the enamel and underlying dentine in a molar tooth; “W_Wear” comprised tooth indentations of irregular shape larger than 7 mm × 7 mm in size; “E_Wear” comprised extensive tooth indentation. “Wear” anomalies were found on 10% of specimens from Buru or the Sula Islands and on 17% of all Sulawesi crania and mandibles. It was hypothesised that tooth grinding of the abrasive seeds of the wild banana (Musa balbisiana Colla) initiated this anomaly. Groove was a deep, oval-shaped cleft cut into the enamel and dentine between two molar teeth. Groove anomalies were evident in 3% of Buru or the Sula Islands specimens and in 12% of all Sulawesi specimens. No conclusion was reached regarding the initiator of the Groove anomaly.

Correlation between Parental-Reported Tooth Grinding and Sleep Disorders: Investigation in a Cohort of 741 Consecutive Children

Purpose. A possible relationship between sleep bruxism (SB) and several sleep disorders has been suggested in children, which could influence sleep quality and quality of life. This study aims to assess such correlations in a large sample of school children. Methods. Parents of 741 consecutive children aged between 8 and 12 years filled the Sleep Disturbance Scale for Children (SDSC). It evaluated 45 items grouped in 8 components: duration of night-time sleep, sleep latency, bedtime problems, sleep quality, night awakenings, nocturnal symptoms, morning symptoms, and daytime sleepiness. An item evaluating parental-reported tooth grinding was also included. Correlation analysis was performed between parental-reported tooth grinding and all the other items. Results. A significant correlation between parental-reported tooth grinding and several sleep disorders concerning bedtime problems, night awakenings, nocturnal symptoms, and morning symptoms has been found. In general, correlation strength of significant pairs was low, ranging from 0.092 (sleep apnea) to 0.234 (movement while falling asleep). Conclusions. Parental-reported tooth grinding in children is correlated, even if weakly, with some sleep disorders concerning the sphere of bedtime problems, night awakenings, nocturnal symptoms, breathing symptoms, and morning symptoms. Further studies are needed to confirm these findings, with particular regard to the consistency of correlation outcomes between the parental reports and the sleep laboratory measures.

New possibilities of worm thread machining and practice of implementation

Thread grinding is the traditional operation of final machining for worms and other critical threads. However, similar to other types of tooth grinding, this type of machining is expensive; it requires application of high cost equipment and needs valuable workers. In many practical cases, its alternative can be the application of edge machining, especially as the possibilities of controlling the corresponding advanced machine-tools and their accuracy have been increased significantly. This paper describes the experience of implementation of edge machining of worm threads within a low-series production of spiroid and worm gearboxes for pipeline valves gained at the Institute of Mechanics named after prof. V.I. Goldfarb of Kalashnikov Izhevsk State Technical University and at the Small Innovative Enterprise “Mechanik”. Schemes of thread machining by straight and radial parts of a single cutter and by a face cutter head are considered. The technique is implemented, and it provides the reduction of labor intensity and prime cost of both the preliminary and final machining of worms, including heat-strengthened ones; and it also results in the correctly localized contact in worm and spiroid gears.

Temporomandibular joint disorders and Gender differences among habitants of Karachi

Background: This study aimed to determine the prevalence of TMDs among the sample of Karachi and to observe the most frequent TMJ sound in this population. Methodology: It was a cross sectional study conducted from Sep 2017 to Nov 2017. Three hundred patients were selected through cluster sample technique from the public/private dental institutes and private dental clinics of Karachi. The data was collected with the help of questionnaire and intraoral examination was performed by the researchers. All those patients with complain of TMDs and between 20-75 years were included in this study. The frequency and association between gender and TMDs were assessed through the application of Chi square. Results: There were more males (n=162, 54%) and (n=138, 46%) females in this study. Majority of participants fall under the age group of 20-30 years of age. Most common TMDs symptom among male was pain during mastication (n=104, 64%) and most common symptoms among female was pain on neck/cervical area which was (n=92, 66%). Headache and earache was the least common symptom among both genders and p-value was 0.003 and 0.024 respectively. Clicking was the most common TMJ sound found among both genders, in male it was (n=58, 35.8%) and in female it was (n=48, 34.7%) followed by crepitation. Regarding parafunctional habits; majority of females (n=95, 68.8%) were in habit of clenching than male (n=60, 37%) and p-value was 0.0001 followed by tooth grinding which was also found mostly in female (n=64, 46.3%) then male (n=10, 6.1%) and p-value was 0.0001. Regarding the risk factors of TMDs; while examination majority of females were found with disturbed articulation,(n= 37,26.8%) and in male it was (n=10, 6.1%), significance difference was found between both genders and p-value was 0.0001. Stress was found to be most common risk factor and aggravating factor of TMDs among both genders. Missing teeth were found in both gender; (n=100, 61.7%) male and (n=71, 51.4%) female and calculated p-value was 0.047. Conclusion: It was inferred from this study that greater prevalence of TMDs was mostly found in female gender. The statistically significant difference was found among stress as an aggravating factor of TMDs and gender. Clicking was the most prevalent TMJ sound and clenching was the most frequently observed parafunctional habit among both gender, followed by tooth grinding and statistically significant difference found among both gender.

Clinical Evaluation of Periodontal Tissue Status in Prosthodontic Treatment of Patients with Partial Tooth Loss and Generalized Periodontitis

The problem of selection and application of dental prostheses in periodontal disease is especially relevant in case of severe generalized periodontitis, which is accompanied by mobile tooth removal resulting in overloading the periodontium of the remaining teeth as well as the increase in tooth mobility. Therefore, in generalized periodontitis, it is important to apply the method of direct dental prosthetic rehabilitation since, in case of partial tooth loss, it will prevent the development of generalized periodontitis complications.The objective of the research was to improve the effectiveness of combination therapy for patients with generalized periodontitis and partial tooth loss applying the developed method of direct fixed dental prosthetic rehabilitation based on the study of the periodontal status.Materials and methods. The study included 129 patients with general periodontitis, II-III degree and partial tooth loss over the age of 45 years. According to prosthodontic treatment, all the patients were divided into three groups: Group I consisted of 42 (20 women and 22 men) patients who immediately after tooth extraction were rehabilitated with the application of direct plastic laminar immediate prosthesis and selective tooth grinding; permanent dental prosthetic rehabilitation was performed 6 weeks after tooth extraction; Group II included 43 (21 women and 22 men) patients who underwent traditional permanent dental prosthetic rehabilitation using fixed dental bridges 6 weeks after mobile tooth removal and wound healing; Group III comprised 44 (21 women and 23 men) patients who immediately after mobile tooth removal were rehabilitated with the application of direct fixed sectional dental bridge (Ukrainian patent UA 20995. 2007 Feb 15) and selective tooth grinding; permanent dental prosthetic rehabilitation was performed 6 months after tooth extraction. The control group consisted of 26 people with intact dentitions over the age of 45 years.Results and discussion. The application of direct dental prosthetic rehabilitation method after mobile tooth removal in combination treatment of generalized periodontitis allows stabilizing degenerative and inflammatory processes in the periodontium in the initial stages, as well as increasing the resistance of the capillaries and bone mineral density of the interdental septa. The obtained data indicated that the application of the proposed direct fixed sectional dental bridge was more effective as compared to conventional prosthetics methods.Conclusions. 1. Direct fixed prosthodontics using direct fixed sectional dental bridge is essential in combination treatment of generalized periodontitis, especially if mobile tooth extraction is needed. It allows increasing the effectiveness of treatment in comparison with direct removable prosthodontics using direct plastic laminar immediate prosthesis (Group I) and traditional treatment methods (Group II). 2. We have proved the advantages of direct fixed prosthodontics in treatment of patients with generalized periodontitis, II-III degree based on the improvement of oral hygiene indices, the gingival bleeding index, the papillary-marginal-alveolar index, the periodontal index and the depth of periodontal pockets 6-12 months after treatment.

Sleep bruxism and sleep disorders in adolescents

Sleep Bruxism, the sleep-related movement disorder of tooth grinding and clenching, is highly reported in pediatrics with a prevalence of up to 40 % during childhood and adolescence. The precise etiology of sleep bruxism remains unknown, but it may involve genetic and psychosocial components (such as anxiety and stress). Clinicians should be aware that quite often sleep bruxism is associated with other disorders, such as snoring, sleep-disordered breathing, sleep complaints, and behavioral problems. These comorbidities should be investigated, because they may be severe and prolonged if they are not treated. SB may lead to morning jaw muscle soreness or pain, headache, masticatory muscle hypertrophy, temporomandibular disorders, and tooth wear. Especially in pediatrics, sleep bruxism is usually managed with conservative therapies, such as sleep hygiene, behavioral modifications, biofeedback, familial counseling and, only in cases of severe tooth wear or other serious possible consequences of SB, soft occlusal splints.