Systematic review and network meta-analysis of restorative therapy and adhesive strategies in root caries lesions.

AIM: This systematic review and network meta-analysis (NMA) aimed to establish a clinically relevant hierarchy of the different adhesive and/or restorative approaches to restore cavitated root caries lesions through the synthesis of available evidence. MATERIALS AND METHODS: A systematic search was conducted in Medline/Web of Science/Embase/ Cochrane Library/Scopus/grey literature. RCTs investigating ≥2 restorative strategies (restorative /adhesive materials) for root caries lesions in adult patients were included. Risk of bias within studies was assessed (Cochrane_RoB-2) and the primary outcome was survival rate of restorations at different follow-up times (6-/12-/24-months). Network meta-analyses were conducted using a random effects model stratified by follow-up times. I2-statistics assessed the ratio of true to total variance in the observed effects. All available combinations of adhesives (1-SE: one-step self-etch; 2-3ER: two-/three-step etch-and-rinse) and restorative materials (conventional composite (CC) as well as conventional and resin-modified glass ionomer cements (GIC, RMGIC)) were included. Risk of bias across studies and confidence in NMA (CINeMA) were assessed. RESULTS: 547 studies were identified and nine were eligible for the NMA. In total, 1263 root caries lesions have been restored in 473 patients in the included clinical trials. Patients involved were either healthy (n = 6 trials), living in nursing homes (n = 1 trial) or received head-and-neck radiotherapy (n = 2 trials). There was statistically weak evidence to favour either of material/material combination regarding the survival rate. A tendency for higher survival rate (24-months) was observed for 2-3ER/CC (OR24mths 2.65; 95%CI=1.45/4.84) as well as RMGIC (OR24mths 2.05; 95%CI=1.17/3.61) compared to GIC. These findings were though not statistically significant and confidence of the NMA was low. CONCLUSION: An evidence-based choice of restorative strategy for managing cavitated root caries lesions is currently impossible. There is a clear need for more standardised, well-designed RCTs evaluating the retention rate of root caries restoration approaches.

Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up.

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height (B = -0.34; 95% CI, -0.65 to -0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

Functional anatomy of the equine temporomandibular joint: Histological characteristics of the articular surfaces and underlining tissues.

It has been assumed that dental conditions cause disorders of the equine temporomandibular joint (TMJ), due to biomechanical overload or aberrant loading. However, the incidence of published TMJ disorders in horses is low and this leads to the question whether the equine TMJ is adapted well to its biomechanical requirements or is able to remodel its articular surfaces in response to modified loading conditions. The aim of this study was to determine the histological characteristics of healthy equine TMJs. The tissue components of the articular surfaces of 10 TMJs obtained from horses without any clinical history of dental or TMJ disorders were analysed. Apart from the mandibular fossa of the temporal bone, the osseous aspects of the TMJ exhibited a uniform zoning pattern. The articular surfaces were composed of three tissue layers: (1) a superficial cell-rich dense connective tissue layer; (2) a middle fibrocartilage layer; and (3) a deep hyaline-like cartilage layer. The articular disc was composed of an inner core of fibrocartilage and hyaline-like cartilage meshwork covered with both cell-rich dense connective tissue and fibrocartilage at its dorsal and ventral aspects. In contrast, the mandibular fossa was only covered by a dense connective tissue, frequently supplemented by a synovial membrane, suggesting low biomechanical stress. Glycosaminoglycans, which are indicative of compressive loads, were predominantly present within the rostral part of the articular tubercle and the retroarticular process, the dorsal part of articular disc and the entire mandibular head, but were absent within the mandibular fossa. The results of this study suggest the presence of different biomechanical demands in the dorsal and ventral compartment of the equine TMJ.

Examination of the Interproximal Wear Mechanism: Facet Morphology and Surface Texture Analysis.

Dentition is considered a dynamic system with forces that directly affect dental treatment stability and success. Understanding the biomechanical forces that influence tooth alignment is essential for both planning and performing dental treatments, as well as for anthropological and evolutionary studies. While there is currently an abundance of research on the mechanics of dental wear at the occlusal surface, the mechanics of interproximal dental wear is largely unexplored. The fretting mechanism, a wear process resulting from small-amplitude cyclic motion of 2 solid contacting surfaces, was refuted as a possible mechanism for occlusal wear but has never been considered for interproximal wear. Therefore, the aim of the current study was to reveal the biomechanical process of the interproximal wear and to explore whether the fretting mechanism could be associated with this process. Premolar teeth with interproximal wear facets were examined by 3-dimensional surface texture analysis using a high-resolution confocal disc-scanning measuring system. The unique texture topography of 3 areas in the proximal surface of each tooth was analyzed by applying 3D dental surface texture analysis. Each area showed unique texture characteristics, presenting statistically significant differences between the inner area of the facet and its margins or the surface outside the facets borders. Based on these results, we concluded that fretting is a key mechanism involved in interproximal wear.

Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces.

In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal typical morphological features indicating biomechanical adaptions. Therefore, the collagen fiber alignment was visualized using the split-line technique in 16 adult warmblood horses without any history of TMJ disorders. Within the central two-thirds of the articular surfaces of the articular tubercle, the articular disc and the mandibular head, split-lines ran in a correspondent rostrocaudal direction. In the lateral and medial aspects of these articular surfaces, the split-line pattern varied, displaying curved arrangements in the articular disc and punctual split-lines in the bony components. Mediolateral orientated split-lines were found in the rostral and caudal border of the articular disc and in the mandibular fossa. The complex movements during the equine chewing cycle are likely assigned to different areas of the TMJ. The split-line pattern of the equine TMJ is indicative of a relative movement of the joint components in a preferential rostrocaudal direction which is consigned to the central aspects of the TMJ. The lateral and medial aspects of the articular surfaces provide split-line patterns that indicate movements particularly around a dorsoventral axis.

Comparative analyses of tooth wear in free-ranging and captive wild equids.

REASONS FOR PERFORMING STUDY: Captive breeding has played a crucial role in the conservation of threatened equid species. Grazing ruminants and rhinoceros in captivity have less abrasion-dominated tooth wear than their free-ranging conspecifics, with potential negative consequences for their health. However, a similar study on wild equids in captivity is missing. OBJECTIVES: The aim was to establish if different tooth wear patterns are exhibited by free-ranging and captive equids. STUDY DESIGN: Cross-sectional study of museum specimens comparing free-ranging and captive equids. METHODS: Dental casts of maxillary cheek teeth of 228 museum specimens (122 from free-ranging and 106 from captive individuals) of 7 wild equid species were analysed using the extended mesowear method. Although teeth showing specific abnormalities were not scored, the presence of focal overgrowths (hooks) of the rostral premolars (106, 206) was recorded. RESULTS: Captive Equus ferus przewalskii, E. grevyi, E. hemionus, E. quagga boehmi and E. zebra hartmannae have less abrasion-dominated tooth wear on their premolars than their free-ranging conspecifics (P<0.001). Fewer differences were exhibited between populations in the molars. No differences were exhibited in the distal cusp of the molars (110, 210) between populations, except in a small sample of E. kiang. Captive equids exhibited more homogeneous wear along the tooth row whereas free-ranging equids exhibited a tooth wear gradient, with more abrasion on premolars than molars. There were more rostral hooks on the premolars (106, 206) in the captive than the free-ranging population (P = 0.02). CONCLUSIONS: Captive equids did experience less abrasion-dominated tooth wear than their free-ranging conspecifics, but the differences in tooth wear were less pronounced than those between captive and free-ranging wild ruminant and rhinoceros species. This indicates that feeding regimes for captive equids deviate less from natural diets than those for captive ruminants and rhinoceros but that factors leading to hook formation, in particular feeding height, should receive special attention. The Summary is available in Chinese - see Supporting information.