Toros Alcan

The effects of a modified protraction headgear on maxilla

Protraction headgears are commonly used in the treatment of Class III malocclusion characterized by maxillary retrognathism. The upward and forward rotation of the maxilla during protraction is a major unwanted side effect. The aim of this study was to eliminate the upward and forward rotation of maxilla while protracting. Seventeen patients with Class III malocclusion as a result of maxillary retrognathism were treated for 3 months; their average age was 12.81 years. A full coverage acrylic cap splint-type rapid maxillary expansion appliance was cemented and activated twice a day for 5 days. After sutural separation, a maxillary modified protraction headgear was worn and 750 g of force was applied. Wilcoxon signed rank test was carried out to evaluate 42 parameters measured on cephalometric radiographs. The maxilla was displaced anteriorly by downward and backward rotation. The mandible was displaced downward and backward due to anterior elongation of the maxilla. Extrusion and lingual tipping of the upper incisors and intrusion of upper molars and downward and backward rotation of functional occlusal plane were observed. The aim of our study was achieved, which was to avoid upward and forward rotation while protracting the maxilla. In conclusion, maxillary modified protraction headgear (MMPH) can be used effectively in Class III patients with retrognathic maxilla and anterior open bite tendency.

The relationship between digital model accuracy and time-dependent deformation of alginate impressions.

OBJECTIVES To investigate the effects of different storage periods of alginate impressions on digital model accuracy. MATERIALS AND METHODS A total of 105 impressions were taken from a master model with three different brands of alginates and were poured into stone models in five different storage periods. In all, 21 stone models were poured and immediately were scanned, and 21 digital models were prepared. The remaining 84 impressions were poured after 1, 2, 3, and 4 days, respectively. Five linear measurements were made by three researchers on the master model, the stone models, and the digital models. Time-dependent deformation of alginate impressions at different storage periods and the accuracy of traditional stone models and digital models were evaluated separately. RESULTS Both the stone models and the digital models were highly correlated with the master model. Significant deformities in the alginate impressions were noted at different storage periods of 1 to 4 days. Alginate impressions of different brands also showed significant differences between each other on the first, third, and fourth days. CONCLUSIONS Digital orthodontic models are as reliable as traditional stone models and probably will become the standard for orthodontic clinical use. Storing alginate impressions in sealed plastic bags for up to 4 days caused statistically significant deformation of alginate impressions, but the magnitude of these deformations did not appear to be clinically relevant and had no adverse effect on digital modeling.

A Miniature Tooth-borne Distractor for the Alignment of Ankylosed Teeth

The ankylosis of a tooth is one of the most difficult clinical problems that an orthodontist faces. In the literature, the treatment protocols for ankylosed teeth are still insufficient and questionable when considering gingival esthetics and conservation of bone health. The purpose of this report is to evaluate and discuss the effects of a newly designed miniature tooth distractor (MTD), which can be used with infrapositioned ankylosed teeth. Two cases with vertically malpositioned incisors were treated using the MTD, and this device was evaluated and compared with the distraction appliances used before in the literature. In conclusion, it was found to be efficient with its small dimensions, ease of application and removal, ease of activation, buccolingual control, and patient tolerance.

In Vivo Disintegration of Four Different Luting Agents

The purpose of this study was to evaluate the disintegration of luting agents. An intraoral sample holder was made having four holes of 1.4 mm diameter and 2 mm depth. The holder was soldered onto the buccal surface of an orthodontic band, which was cemented to the first upper molar in 12 patients, average age 26 years. The holes were filled with a zinc phosphate (Phosphate Kulzer), a glass ionomer (Ketac Cem), a resin-modified-glass ionomer (Fuji Plus), and a resin cement (Calibra). Impressions were made at baseline, and 6, 12, and 18 months from which epoxy replicas were made, which were scanned with an optical scanner. Total volume loss was calculated. The rank order of mean volume loss was as follows: Phosphate cement > Ketac Cem = Fuji Plus = Calibra. Cement type and time had statistically significant effects on volume loss of cements (P < 0.001). Under in vivo conditions, zinc phosphate cement disintegrated the most, whereas no significant difference was observed for glass ionomer and resin-based cements. As intraoral conditions are considerably less aggressive than experimental laboratory conditions, the erosion behavior of glass ionomer cement was found to be similar to the resin-based cements in contradiction to previous laboratory results.

The Effect of 2 Different Distraction-Compression Models on New Bone Generation

PURPOSE To compare the stimulating effect of distraction and 2 different distraction-compression models on maturation of new bone during healing. MATERIALS AND METHODS Thirty adult Sprague-Dawley rats underwent unilateral mandibular osteotomy. The animals were divided into 3 groups. A unidirectional external distraction device was fixed to the mandible. A total of 4 mm of distraction was planned in all groups. After a latency period of 3 days, 0.2 mm of distraction was performed twice a day for 10 days in the distraction group. In the intermittent distraction-compression group, 0.2 mm of distraction was performed twice a day for 3 days, followed by 0.2 mm of compression twice a day for 1 day. In the overdistraction-compression group, 0.2 mm of distraction was performed twice a day for 14 days, followed by 0.2 mm of compression twice a day for 4 days. After a consolidation period of 6 weeks in all groups, animals were killed for macroscopic, microscopic, and radiologic evaluation. RESULTS Radiologic evaluation proved that more mature bone generation occurred in the groups in which compression was added to distraction. The number of osteoblasts in the intermittent distraction-compression group was significantly higher than that in the distraction group and overdistraction-compression group (P < .001). The highest number of vessels was found in the intermittent distraction-compression group (17.7 ± 6.4) (P < .001). CONCLUSIONS The intermittent distraction-compression model was found to generate greater new bone compared with distraction alone. In clinical applications, to increase the quality of the bone and to shorten the consolidation period, compression can be applied during distraction.

Tek Taraflı Dudak-Damak Yarıklarında Nazoalveolar Şekillendirme: İki Olgu

OZET Nazoalveolar sekillendirme, dudak damak yarikli yenidoganlarda varolan deformitenin siddetinin primer onarimdan once azaltilmasini amaclayan bir yontemdir. Bu yontem ile yarik bolgesinin iki tarafindaki segmentler doku eks-pansiyon prensipleri kullanilarak yaklas-tirilabilir ve simetri saglanabilir. Ayrica burun kikirdaginin erken donemde sekillendirilebilme ozelliginden faydalanilarak burun kanadi ve kolumella diklestiri-lebilir. Bu raporda farkli tek tarafli dudak-damak yarik tipine sahip iki ayri bebegin bu yontem ile tedavisine iliskin ayrintilar ve primer dudak onarimi sonrasi sonuclari sunulacaktir.