Asymmetry of dental or joint anatomy or impaired chewing function contribute to chronic temporomandibular joint disorders.

INTRODUCTION: The etiologies of most chronic temporomandibular joint disorders are unknown. However, an association between habitual chewing on a particular side and chronic temporomandibular joint disorders has been reported. The aim of this study was to investigate the differences between sides (affected vs unaffected) of biodynamic factors (including lateral dental guidance determined by dental anatomy) or condylar path angles (determined by temporomandibular joint morphology) and chewing function (physiological alternate chewing vs single habitual chewing side). The study scope was to investigate possible etiological factors to improve the understanding of temporomandibular joint disorders. The null hypothesis was that no difference would be found between sides that are or are not affected by chronic temporomandibular joint disorders in chewing function or in levels of dental or temporomandibular joint remodeling. METHODS: This cross-sectional, double-blind study involved 24 adults with substantial, chronic, unilateral symptoms diagnosed as temporomandibular joint disorders. Chewing function, temporomandibular joint remodeling (using axiography) and dental anatomy (lateral guidance angles using kinesiography) were assessed. RESULTS: Habitual chewing on one particular side was observed in 17 of 24 participants; significantly more (n=15) chewed on the affected side than on the unaffected side (P=0.002 in a two-tailed Fisher's exact test; risk estimate=4.5; 95% CI 1.326-15.277). The condylar path (CP) angle was steeper on the affected side than on the unaffected side (mean (standard deviation)=50.52° (9.98°) versus 45.50° (7.98°); P=0.002 in a two-tailed t-test). The lateral guidance (LG) angles were flatter on the affected side in all 24 participants. CONCLUSION: Our results suggest that habitual chewing on one side may be associated with increasing condylar path, with flattening lateral guidance angles, and also with chronic temporomandibular joint disorder on the habitual chewing side.

Integral representation of generalized grey Brownian motion.

In this paper, we investigate the representation of a class of non-Gaussian processes, namely generalized grey Brownian motion, in terms of a weighted integral of a stochastic process which is a solution of a certain stochastic differential equation. In particular, the underlying process can be seen as a non-Gaussian extension of the Ornstein-Uhlenbeck process, hence generalizing the representation results of Muravlev, Russian Math. Surveys 66 (2), 2011 as well as Harms and Stefanovits, Stochastic Process. Appl. 129, 2019 to the non-Gaussian case.

Guidelines for occlusion strategy in implant-borne prostheses. A review.

Medium- or long-term failure of endosseous dental implants after osseointegration, when it has occurred, has been associated in the great majority of cases with occlusal overload. Overload depends ultimately on the number and location of occlusal contacts, which to a great extent are under the clinician's control. Much of our current understanding of occlusal contacts in this context is based on concepts derived from non-implant-borne prosthetics and has not been rigorously tested. The present article reviews occlussal contact designs and offers occlusion strategy guidelines for the main types of implant-borne prostheses.

Midline shift and lateral guidance angle in adults with unilateral posterior crossbite.

INTRODUCTION: Unilateral posterior crossbite is a malocclusion that, if not corrected during infancy, typically causes permanent asymmetry. Our aims in this study were to evaluate various occlusal parameters in a group of adults with uncorrected unilateral posterior crossbite and to compare findings with those obtained in a group of normal subjects. METHODS: Midline shift at maximum intercuspation, midline shift at maximum aperture, and lateral guidance angle in the frontal plane were assessed in 25 adults (ages, 17-26 years; mean, 19.6 years) with crossbites. RESULTS: Midline shift at maximum intercuspation was zero (ie, centric midline) in 36% of the crossbite subjects; the remaining subjects had a shift toward the crossbite side. Midline shift at maximum aperture had no association with crossbite side. Lateral guidance angle was lower on the crossbite side than on the noncrossbite side. No parameter studied showed significant differences with respect to the normal subjects. CONCLUSIONS: Adults with unilateral posterior crossbite have adaptations that compensate for the crossbite and maintain normal function.

Unilateral posterior crossbite and mastication.

OBJECTIVE: This study was designed to characterize masticatory-cycle morphology, and distance of the contact glide in the closing masticatory stroke, in adult subjects with uncorrected unilateral posterior crossbite (UPXB), comparing the results obtained with those obtained in a parallel group of normal subjects. STUDY DESIGN: Mandibular movements (masticatory movements and laterality movements with dental contact) were registered using a gnathograph (MK-6I Diagnostic System) during unilateral chewing of a piece of gum. Traces were recorded on the crossbite and non-crossbite sides in the crossbite group, and likewise on both sides in the non-crossbite group. RESULTS: Mean contact glide distance on the crossbite side in the UPXB group was significantly lower than in the control group (p<0.001), and mean contact glide distance on the non-crossbite side in the UPXB group was significantly lower than in the control group (p=0.042). Cycle morphology was abnormal during chewing on the crossbite side, with the frequency distribution of cycle types differing significantly from that for the noncrossbite side and that for the control group (p<0.001). CONCLUSIONS: Patients with crossbite showed alterations in both contact glide distances and masticatory cycle morphology. These alterations are probably adaptive responses allowing maintenance of adequate masticatory function despite the crossbite.

A titanium and visible light-polymerized resin obturator.

Obturator prostheses are typically large, and their weight and size are often important design factors. This article describes the fabrication of an obturator prosthesis with a titanium framework and visible light-polymerized denture base resin. It is speculated that these low-density materials may produce prostheses lighter than similar ones made with conventional materials. An added advantage is that visible light-polymerizing resins facilitate relining.