牙周病正畸患者临床常见拔牙模式分析

目的探讨牙周病患者正畸矫治常见的临床拔牙模式。方法选取48例牙周病正畸拔牙患者，对拔牙模式进行分析。结果选取的48例牙周病正畸患者中存在多种拔牙模式。结论牙周病正畸患者拔牙模式存在显著多样性。     

Tissue reactions towards titanium implants inserted in growing jaws. A histological study in the pig.

In this investigation, the tissue reactions towards titanium implants inserted in growing jaws of pigs were studied by means of histology. At the age of 12 weeks, 5 test pigs each received 4 Brånemark System* titanium implants (fixtures). The fixtures were inserted immediately after extraction of the mesial root of the second deciduous premolar (P2) and the deciduous canine (C) on one side of the mandible and the mesial root of the first deciduous premolar (PI) on the other side. The fourth implant was placed after extraction of the deciduous lateral incisor (L) on one side in the upper jaw. Furthermore, 1 pig in which no extractions or fixture installations were performed served as a control. All pigs were followed for 165 days with clinical, radiographic and biometric examinations, the results of which have been previously presented. In this study, 10‐μm‐thick ground sections were produced for histology after the jaws had been fixed by immersion in formalin and further processed and embedded in plastic resin. Six of the fixtures originally inserted were lost during the experimental period, and the remaining implants were found to be involved with mineralized bone to varying degrees. Regarding the fixture‐to‐teeth relationship, it was found that, in the premolar region of the lower jaw, the teeth were positioned superior to and buccally angulated in relation to the fixtures. In the upper jaw, the implants were positioned below the adjacent teeth but centrally in the alveolar process. Tooth germs adjacent to the fixture had a displaced eruption path, buccally or lingually to the fixture. If the bud developed in close contact with the fixture, a changed morphology of the germ could be observed.     

Elimination of hyalinized periodontal tissues associated with orthodontic tooth movement

ABSTRACT – The elimination of orthodontically produced hyalinized tissue in the marginal region of the periodontal ligament has been studied with the electron microscope. From a material of 67 rats in which the first molar had been moved buccally with a fixed appliance for a period of 30 min to 28 d, 20 specimens representing experimental periods of 48 h to 14 d revealed that the hyalinized structures disappeared concomitantly with an invasion of cells and blood vessels from the neighboring periodontal ligament. The removal of collagen, cell remnants and degraded vascular elements apparently was mediated by different forms of cellular activity. Breakdown of collagen fibrils was observed around cell processes as well as in inclusions within the cytoplasm of the invading pioneer cells. Penetration of new blood vessels seemed to be an important factor in the elimination of hyalinized tissue. Remnants of cells and erythrocytes were removed by phagocytic activity, while more extensive amorphous masses of vascular components were eliminated by foreign body giant cell activity. Identification of the invading cells has been discussed in relation to current concepts of connective tissue cell differentiation.     

Meta analysis of the treatment-related factors of external apical root resorption

OBJECTIVE: To elucidate possible treatment-related etiological factors--such as, duration of treatment and apical displacement--for external root resorption. DESIGN: Meta-analysis of the available English-language literature. INCLUSION & EXCLUSION CRITERIA: Papers with a sample size > 10, fixed appliances, pre- and post-operative radiographs, and apical displacement recorded were included. History of trauma, prior root resorption and endodontic treatment were excluded. Appropriateness of these selections was tested with a 'funnel plot' analysis. OUTCOME MEASURE: Correlations between root resorption, apical displacement, and treatment duration. RESULTS: Mean apical root resorption was strongly correlated with total apical displacement (r = 0.822) and treatment duration (r = 0.852). CONCLUSION: The treatment-related causes of root resorption appear to be the total distance the apex had moved and the time it took.     

Modified IOTN: an orthodontic treatment need index for use in oral health surveys

This paper reports the results of a study of the reliability of a modified version of the Index of Orthodontic Treatment Need (IOTN) for use in oral health surveys. Twelve non-specialist dental examiners were trained in the use of the Modified IOTN using a standardised teaching protocol lasting approximately 1.5 hours. Following a school-based calibration exercise it was found that nearly all the examiners achieved either good or excellent agreement (mean Kappa=0.74). The average sensitivity and specificity scores were 0.90 and 0.84, respectively. The Modified IOTN appears to overcome the training and reliability problems that often accompany the use of orthodontic indices by non-specialists in oral health surveys.     

Ingestion of a quadhelix appliance requiring surgical removal: a case report

Abstract

This report presents an unusual case, whereby a 13-year-old Down’s syndrome boy accidentally swallowed a removable quadhelix appliance that subsequently required surgical removal. The paper discusses management strategies for patients who have accidentally swallowed components of their orthodontic appliance. It also highlights the need for orthodontists to consider limited objective treatment options for certain patient groups.     

A modified over-tie for the ligation of Incognito™ lingual fixed appliances

Abstract

The Incognito lingual appliance has a ribbon-wise slot with vertically inserted wires. Control of tip can be problematic with this appliance and the conventional method to overcome this is to achieve full wire engagement via the use of power-ties. Although effective, these can be very difficult to place and also create very high friction. A method of ligation is described which consists of a modified elastic double over-tie. This is easily placed and very effective at controlling tip in Incognito brackets using a variety of arch wires. This method creates less friction than the power-tie.     

The maxillary rotation: Its relation to the cranial base and the mandibular corpus An implant study

A material of 22 patients with metallic implants was used in a longitudinal study, based on lateral head-plates, of the relationship between: 1) the maxillary rotation and the cranial base 2) the maxillary rotation and the different mandibular rotations. No connection has been found between the variation of the maxillary rotation and the growth of the cranial base. The correlation between the maxillary and the mandibular rotations is the highest when the rotation of the corpus is considered. A strong correlation is found between the variation of the condylar growth direction and the variation of the maxillary rotation.