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Adjustment of the occlusal vertical dimension in the bite-raised guinea pig.

In humans, the inappropriate occlusal vertical dimension (OVD) causes several orofacial disorders, such as bruxism and pain in the masticatory muscles and temporomandibular joint. However, it is still unclear how strictly the OVD is adjusted. To answer this question, we studied the temporal change of the OVD in bite-raised young guinea pigs. The OVD was raised by fixation of a bite-raising appliance to the lower incisors, and increased by either 3 or 1.5 mm at the first molars. After the space produced between the upper and lower molars was filled within 10 days due to eruption of the molars, the appliance was removed. In the bite-raised animals, the raised OVD was reduced until it attained that observed in the control animals, after which the OVD increased according to cranial growth. These results show that the OVD is developmentally changed and strictly controlled.

Adaptation, Physiological↗

Distraction osteogenesis may promote periodontal bone regeneration.

Distraction osteogenesis has numerous applications in the treatment of conditions affecting the dentofacial complex, from midface advancement to orthodontic tooth movement produced by transversal distraction of the periodontal ligament. The purpose of this study was to test the hypothesis that periodontium can be consistently distracted toward the tooth crown to promote periodontal bone regeneration. After the surgical production of periodontal defects in maxillary canines of 5 mongrel dogs, periodontal bone distraction was performed. Light microscopy was used for histopathological and morphometric analysis. Periodontal bone regeneration occurred in all animals. Periodontal bone regeneration in the distraction sites (Mean +/- SD: 5.45 +/- 2.01 mm) differed from that in control sites (0.008 +/- 0.67 mm; p < 0.0001). Periodontal bone distraction resulted in periodontal bone regeneration. This finding may establish periodontal bone distraction as a new treatment alternative for periodontal defects.

Alveolar Process↗

Emergency maxillofacial radiology. Foreign body localization: report of cases.

Successful emergency removal of foreign bodies of the maxillofacial complex depends on the surgeon's ability to perform exact location procedures. In hospitals and/or offices where advanced imaging technologies are not available, the attendant clinician has to use and rely on variations of conventional radiographic techniques in order to complement the diagnosis and locate the foreign body. Three cases are presented where unconventional radiographic techniques were used, leading to successful surgical removal of foreign bodies.

Adolescent↗

[An evaluation of the biting force, the body composition and the amount of masticatory action in young females].

UNLABELLED: The purposes of this study were to investigate factors related to maximum biting force and to understand the characteristics of physical properties of daily ingested foods in young females. One hundred and forty subjects aged 18-23, with Angle 1 class occlusion, had not suffered from periodontitis, and had not been treated for preparation of tooth crown of first molars. Body height and weight were measured, and percentage of body fat, fat mass (FM) and lean body mass (LBM) were estimated, using the impedance analyzer. The maximum biting force was measured by the press sensation method. According to the formula on the basis of our new version of Yanagisawa's food classification, the mean value of the amount of masticatory action for one day was calculated. Subjects were divided into the normal biting force and the low biting force groups with -1SD of the maximum biting force, in order to compare body composition and backgrounds in sports activities between these two groups. Multiple linear regression analysis was carried out, employing maximum biting force (kg.f) as a dependent variable, and having a background in sports activities, FM, LBM, the number of missing teeth, the number of dental caries and the amount of masticatory action for one day as independent variables. Results were as in the following: 1) The proportion of subjects who had a background in sports activities in the low biting force group were less than that in the normal biting force group (p < 0.01). 2) Having a background in sports activities and LBM were positively correlated to maximum biting force (p < 0.01), while the amount of masticatory action for one day was not. 3) All subjects, especially those in the low biting force group seldom had food requiring the highest amount of masticatory action. CONCLUSION: Having a background in sports activities and LBM are positively correlated with the maximum biting force, while the amount of masticatory action for one day was not correlated positively nor negatively in young females.

Adolescent↗

Periodontal signs and symptoms associated with vertical root fracture.

This report describes the clinical presentation of three cases of vertical root fractures in adult patients where an initial diagnosis of localized periodontitis had been considered. Loss of the affected tooth occurred in all of these patients. The effects of endodontic therapy and the provision of post-retained restorations are considered in relation to their potential effect of weakening the root and predisposing the tooth to vertical fracture. The last case presents an unrestored molar tooth with a complete vertical root fracture.

Adult↗

Evaluation of techniques and material used in pulpal therapy based on a review of the literature: part II.

A healthy and functional dental pulp is the goal of any treatment procedure, but at present there does not seem to be any material that will regularly induce dentinal bridge formation and healing of an exposed, inflamed pulp. The usefulness of various capping agents, including corticosteroids and isobutyl cyanoacrylates, is interpreted. In determining treatment, all the clinician's experience is needed in correlating clinical evidence, history, size of the filling in relation to the tooth crown and periodontal condition.

Adrenal Cortex Hormones↗

Restoration fractures, cusp fractures and root fragments in a diverse sample of adults: 24-month incidence.

BACKGROUND: There are few reports in the literature regarding estimates of the occurrence of tooth fractures. Most studies have assessed tooth fractures in people seeking dental care, which may underestimate the incidence of the problem. METHODS: This study sought to estimate the incidence and prevalence of cusp and restoration fractures, as well as root fragments in participants in the Florida Dental Care Study, a diverse representative sample of community-dwelling residents of four north Florida counties made up of people who seek dental care regularly and those who do not. Participants received a dental examination and an in person interview at baseline and at a 24-month follow-up session. RESULTS: At least 20 percent of the participants were diagnosed as having bulk restoration fractures, cusp fractures or root fragments at the baseline visit. At the 24-month follow-up session, 26 percent of the participants had at least one new occurrence of these problems. Of those subjects presenting with tooth fracture, 25 percent had multiple teeth affected. African-Americans and people who sought care on a problem-oriented basis experienced twice the rate of cusp fracture and a higher rate of root fragments as did those who sought care on a regular basis. These data represent consecutive prevalence estimates rather than the true incidence, in that fractures that occurred after baseline may have been treated in the intervening 24 months. Thus, these data represent "lower-bound" incidence estimates. CONCLUSIONS: These results suggest that restoration fractures, cusp fractures and root fragments are a significant dental health problem, and that selected segments of the population are at greater risk of developing these problems. CLINICAL IMPLICATIONS: These data are useful for dentists in understanding the magnitude of the problem and the potential progression of fractures and root fragments.

Adult↗

Prevalence of cusp fractures in teeth restored with amalgam and with resin-based composite.

BACKGROUND: Complete cusp fracture in restored teeth is a common problem observed in general dental practice. Many dentists believe that teeth restored with amalgam are more likely to be associated with cusp fractures than are those restored with resin-based composite. METHODS. The authors noted the condition of 10,869 posterior teeth with amalgam or resin-based composite restorations with at least one cusp present, unrestored or missing in 1,902 consecutively seen adult patients in a private general dental practice. For each patient, the authors recorded age, type of restorations, number of surfaces of each restoration, and presence or absence of a complete cusp fracture and of caries. RESULTS: There was a lower percentage of cusp fractures in younger subjects than in older subjects and in teeth with a single restored surface than in those with more than one restored surface. There was no significant difference in the prevalence of cusp fracture rates in amalgam-restored teeth versus composite-restored teeth in subjects aged 18 through 54 years. In subjects aged 55 through 96 years, there was a marginally significantly greater cusp fracture rate in composite-restored teeth than in those restored with amalgam. Overall, there was no significant difference in the prevalence of cusp fracture in teeth restored with amalgam (1.88 percent) versus composite-restored teeth (2.29 percent). CONCLUSIONS: The prevalence of cusp fractures in amalgam-restored teeth and resin-based composite-restored teeth is not significantly different. Teeth with more than one surface restored with either resin-based composite or amalgam and teeth in older subjects were more likely to suffer a cusp fracture. CLINICAL IMPLICATIONS: Teeth restored with amalgam and with resin-based composite exhibited equally low cusp fracture prevalence. When choosing between amalgam and resin-based composite in consideration of the likelihood of a future cusp fracture, either restorative material is acceptable.

Adolescent↗

Esthetics and super glue: a case report.

This article describes how a man attempted to repair damage to his maxillary teeth with super glue. Such action is discouraged, however, because of possible adverse reactions in the hard and soft tissues.

Adhesives↗

Bilateral fusion of mandibular second molars with supernumerary teeth: case report.

Fusion is a developmental anomaly characterized by the union of two adjacent teeth. In this article we report a rare case of bilateral fusion of permanent mandibular second molars with supernumerary teeth. The rarity with which this entity appears, along with its complex characteristics, often make it difficult to treat. The endodontic management of one tooth is described, as well as the successful treatment of a periradicular lesion.

Adolescent↗

Structure and microstructure of coronary dentin in non-erupted human deciduous incisor teeth.

The dentin structure of non-erupted human deciduous mandibular and maxillary central and lateral incisor teeth was studied employing light and scanning electron microscopy. For light microscopy, nitric-acid-demineralized and ground sections were used. The sections were stained by hematoxylin-eosin, picrosirius and azo-carmine methods, and ground specimens were prepared using a carborundum disk mounted in a handpiece. For SEM study, teeth were frozen in liquid nitrogen and fractured at longitudinal and transversal directions. Structurally, demineralization and ground methods revealed tubules with primary and secondary curvatures, canaliculi, giant tubules, interglobular dentin, predentin, and intertubular dentin. Scanning electron microscopy showed three-dimensional aspects of dentinal tubules, canaliculi, peritubular dentin, intertubular dentin, and predentin. This study contributes to knowledge about dentin morphology showing characteristics of teeth not yet submitted to mastication stress.

Dentin↗

Educational material of dental anatomy applied to study the morphology of permanent teeth.

The purpose of this report is to present educational material that would allow the dental student to learn to easily identify the morphologic characteristics of permanent teeth, and how they fit together (occlusion). In order to do this, macro models of permanent teeth with no attrition were carved in wax and later molded with alginate. These molds were filled with plaster, dental stone and/or cold-cured acrylic resin. The large individual dental stone tooth models were mounted on a wax base, thus obtaining maxillary and mandibular arches which were occluded. These dental arches were molded with plaster or dental stone. The authors suggest that these types of macro models allow an excellent visualization of the morphologic characteristics of permanent teeth and occlusion. Dental students are able to carve the permanent dentition in wax with great facility when they can observe macro models.

Acrylic Resins↗

Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion.

This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.

Adolescent↗