Seyed Mohammadreza Safavi; Mehdi Ravadgar; Fatemeh Mashhadiabbas; D. Sharifi; Alireza Akbarzadeh Baghban
Abstract
Background and aims: To evaluate the frequency of ankylosis, loss of pulp vitality and external root resorption after intentional root contact with mini-screw.Methods: Sixty maxillary and mandibular second, third, and fourth premolars teeth of five mature beagle dogs were randomly assigned into three ...
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Background and aims: To evaluate the frequency of ankylosis, loss of pulp vitality and external root resorption after intentional root contact with mini-screw.Methods: Sixty maxillary and mandibular second, third, and fourth premolars teeth of five mature beagle dogs were randomly assigned into three experimental groups. Premolars teeth at group I, received a mini-screw (6-mm length, 1.5mm diameter, self drilling) which was removed immediately after contact with the root. Group II consisted of teeth that received mini-screw and the screw left in situ for 15 weeks. In group III once contact was made with mini-screw, the teeth were shifted away from the screw with brackets and Titanium closed coil spring tightened to another bonded orthodontic brackets on the neighbor teeth. Group IV was the control group. The specimens were decalcified, stained and evaluated histologically to determine the presence/absence of root resorption, ankylosis and tooth vitality.Results: There were no signs of ankylosis, root resorption, moderate to severe inflammation or necrosis within the pulp in any experimental group.Conclusions: Ankylosis, pulp necrosis and sever root resorption are not common clinical outcomes when mini-screw contacts the root. Repair after contact with mini-screw depends on the severity of invasion. More severe invasion needs further time necessary for repair.
Mahtab Nouri; Arash Farzan; Alireza AkbarZadeh Baghban
Abstract
Background and aim: The aim of present study was to compare the 4th degree polynomials’ drawings generated by the invented laser scanner and ones generated by a CMM. Materials and methods: This diagnostic experimental study was conducted on maxillary and mandibular orthodontic study casts ...
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Background and aim: The aim of present study was to compare the 4th degree polynomials’ drawings generated by the invented laser scanner and ones generated by a CMM. Materials and methods: This diagnostic experimental study was conducted on maxillary and mandibular orthodontic study casts of 18 adults with normal Class I occlusion. First, coordinates of the points on all casts were measured by a CMM. Then, three-dimensional coordinates (X, Y, Z) of the points on the same casts were measured by a 3-D laser scanner designed in Shahid Beheshti University, Tehran.The validity and reliability of each of the systems were assessed by means of Intraclass Correlation Coefficient (ICC) and the root mean square(RMS). Results: The mean RMS for CBPs obtained from CMM and the fitted polynomial for upper and lower dental models was 0.885. The mean RMS for these CBPs on the custom defined polynomial obtained from the laser scanner was 0.911. The mean correlation coefficient for CBPs obtained from CMM and the fitted polynomial for upper and lower dental models was 0.996. The mean correlation coefficient for these CBPs on the custom defined polynomial obtained from the laser scanner was 0.994.Conclusion: The invented laser scanner is nearly as accurate as a CMM in providing an arch form drawing by recording of CBPs on the teeth and use of a 4th degree polynomial fitted to them.