[Histological evaluation of micro implant-bone interface following immediate versus delayed loading in a dog's mandibular bone]

Skeletal anchorage devices such as microimplants are successful attempts to have absolute anchorage. The aim of this study was to evaluate the effect of immediate and delayed orthodontic loading on maxillary and mandibular microimplants regarding histologic responses and bone implant contact [BIC] in a dog. Thirthy-two microimplants [Abso Anchor] were bilaterally placed in the mandibular premolar regions of four adult male dogs. The microimplants were divided into loaded and unloaded [control] groups. The control group had two subgroups of 4 and 8 weeks and the loaded group comprised two subgroups of immediate and delayed [after 4 weeks healing period] loading. Loaded samples were subjected to 200g load provided by Ni-Ti coil spring for 4 weeks. The decalcified specimens were prepared for histological examination under light microscope. The microimplants' surrounding tissue was observed histologically and the bone implant contact [BIC] percentage was calculated in each sample. Three way ANOVA was used to compare BICs in different groups. Mobility was detected in two mandibular microimplants, so the survival rate was calculated as 93.7%. BIC values were not significantly different between loaded and unloaded groups, and between immediate and delayed loaded groups. Immediate or delayed loading of microimplants does not load to significant difference in the bone-microimplant contact

Cephalometric criteria in adolescents with anterior open bite in northern east of Iran

Open bite is concerned as a malocclusion with a difficult treatment and challenging stability. Being aware of etiologic factors of anterior open bite is essential for correct diagnosis and convenient treatment planning. The aim of this study was to evaluate cephalometric criteria in open bite adolescent patients in Mashhad. In this retrospective study, Lateral cephalograms of 40 patients with anterior open bite as case group, and 40 patients with normal overbite and class! molar and canine relationship as control group were selected. Cephalometric criteria were determined and compared in two groups. To compare two groups Student's t-test with 0.05 significance level was used. Cephalometric parameters in males and females within each group, and between the total samples of two groups were compared. There was no significant difference between cephalometric parameters of males and females in each group. In comparing the total samples of two groups Yaxis-SN, lower facial height, anterior facial height, FH-SN, ManP-SN, ManP-FH, ManP-PP, Ul-SN, Ul-FH, Ul-PP, and ANB were significantly greater in open bite group while PFH/AFH, UFH/LFH, and IMPA was significantly lower in this group. There was no significant difference between two groups in other cephalometric criteria. This study demonstrated that in open bite patients there is tendency toward: 1 -ClassII skeletal relationship 2-Vertical growth and increase in LFH 3-Labial inclination of upper incisors 4- Lingual inclination of lower incisors

[Comparison of palatal width and depth between the patients with posterior cross bite and patients without posterior cross bite]

Nowadays, posterior cross bites are a relatively common malocclusion in societies. Basically, the first step in treatment abnormalities is recognition of it completely. The treatment of cross bites is not an exception from this rule. We must be aware of all of the skeletal and dental morphology of cross bite for treatment of it. The aim of this study was to compare the palatal width and depth between the patients with bilateral posterior cross bite and patients without posterior cross bite. In this case-control study, we considered the dental casts of 30 persons [22 girls and 8 boys] with ages ranging from 7 to 14 years with bilateral posterior cross bite as the case group and dental casts of 30 persons [22 girls and 8 boys] with ages ranging from 7 to 14 years without posterior cross bite as the control group. Dental parameters of palatal depth, maxillary intermolar width, maxillary interpremolar [or the first decidous molar] width and mandibular intermolar width were measured. These measurements were done by korkhaus instrument and student-t-test was used for analysis of data. None of the parameters were significantly different between girls and boys in both groups, except for mandibular intermolar width which was greater in boys in control [P=0.016] and case [P=0.01] groups. In both boys and girls with posterior cross bite, maxillary intermolar and interpremolar width was smaller, palatal depth was higher and mandibular intermolar width was larger compared with those without posterior cross bite [P<0.05]. Therefore in all cases with posterior cross bite compared with those without posterior cross bite, palatal depth was higher, mandibular intermolar width was larger, and maxillary intermolar and interpremolar width was smaller [P<0.001]. It can be concluded that in patients with bilateral posterior cross bite compared with patients without this type of malocclusion, palatal depth was higher and maxillary width was smaller

Evaluation of prevalence of dental malocclusion in students of junior high school students in the city of Neishabour in year 2002-2003

The purpose of this study was to evaluate the prevalence of different types of dental malocclusions in the city of Neishabour. In this descriptive- cross sectional study, 469 students [215 girls and 254 boys] with ages ranging from 12 to 15 were randomly selected among 20130 junior high school students in the city of Neishahour. The occlusal characteristics of these students including profile situation, molar and canine relationships on the basis of Angle classification, overjet, overbite, and the type of malocclusion, were recorded on data sheets. To compare the results between boys and girls, chi-square test was used. To compare the results of this study with other studies, Z statistical test was used. A confidence level of 95% was considered in this study. The results of this study indicated that 13.7% of samples had normal occlusion, while 54% had class I malocclusion, 16.4% had class II Div I malocclusion, 6.8% had class II Div 2 malocclusion, and 9.2% demonstrated class Ill malocclusion. Except in overbite and anterior openbite [which revealed more reduction in boys], there was no significant difference in other types of malocclusions between boys and girls. Only 13.7% of the sample population had normal occlusion, and the remaining 86.3% had some type of malocclusion. Therefore considering the high prevalence of malocclusion, care should be taken for prevention and ontime treatment schedules