[Association between cephalometric parameters and anteroposterior position of the upper first permanent molar]

In Angle classification, the maxillary first molar furnishes more nearly than any other tooth or point in the anatomy an exact scientific basis from which to reason on malocclusion. Angle believed that malocclusions are of the mandibular origin. The purpose of this study was to evaluate the association between some cephalometric parameters and sagittal position of the maxillary first permanent molar. This was a descriptive analytical study in which 250 lateral cephalometric samples that were randomly selected before orthodontic treatment were examined. The samples were divided into two groups marked as mixed dentition and permanent dentition. Statistical analyses including the linear correlation coefficients and student t-test were used to compare the upper molar position in two groups. There was no significant correlation between the age, maxillary length, and ANB in two groups. The position of maxillary first molar in the permanent dentition demonstrated a significant positive relationship with ANS-PNS, Jaraback index, and Ba-PTM whereas a significant negative correlation was found with FMA and Basal angle. Moreover, the maxillary first molar position in the mixed dentition showed a significant positive relationship with Ba-A and Ba-PTM. Based on results found in the present study, the sagittal position of maxillary molar between mixed and permanent dentition was different. Maxillary first molar position in the permanent dentition showed a significant relationship with facial growth pattern, facial depth, and maxillary length. However, more longitudinal studies to confirm the findings of this study are needed

Comparison of some cephalometric indices in skeletal class III with skeletal class I patients

The individual variations in patients with skeletal class III malocclusions affect the cephalometric indices e.g., the curve of cranial base and anteroposterior displacement of nasion and the SN inclination can affect the cephalometric indices such as the ANB angle. The aim of this study was to compare some cephalometric indices in skeletal class III with skeletal class I patients as control group. Samples in this Case-control study were 65 lateral cephalometric radiographs randomly selected before the orthodontic treatment. The samples were divided into two study and control groups with skeletal class III relationship [ANB<1] and skeletal class I relationship [2

[Effect of topical application of fluoride on the shear bond strength of fissure sealant]

Pit and fissure sealants and topical fluoride are the most important methods to prevent caries in children and adolescents. It was assued that application of fluoride materials has a negative effect on the bond of adhesive materials such as fissure sealant to teeth. If this is not proved then fluoride therapy can be done before fissure sealant at the same session. The aim of this study was to evaluate the effect of topical fluoride application prior to acid etching on the retention of pit and fissure sealant. In this experimental in vitro study 28 extracted human permanent premolars were used. Each tooth was embedded in dental stone so that the buccal surface was perpendicular to the long axis of the stone block. The teeth were randomly assigned to two groups [n=14]. The facial surfaces of all the teeth were freshened by 600 grit silicon carbide paper. The specimens were cleaned with rubber cups and aqueous slurry of pumice, and then rinsed and dried. In the test group, APF gel was applied on the enamel surface and left for four minutes. Then, it was rinsed for 15 seconds. In both groups, etching was done with 37% phosphoric acid for 30 seconds, followed by a water spray wash for 30 seconds and drying for 15 seconds. The fissure sealant, Helioseal F, was then applied to the etched enamel, using a cylindrical plastic tube [3mm x 3mm] perpendicular to the buccal surface. The sealant was cured. The plastic matrix was carefully removed and the specimens were placed in distilled water for 72 hours. Shear bond strength was evaluated, using a universal testing machine. A shear force was applied to the tooth at a cross-head speed of 1 mm/min. Data were analyzed with Mann-Whitney test. The mean shear bond strength was 17.7 +/- 5.28 for the control and 19.66 +/- 4.27 Mpa for the test group. There was no statistically significant difference in the shear bond strengths between the two groups [p > 0.05]. The results of this study showed that application of fluoride does not affect the shear bond strength of fissure sealant to the enamel

[Changes of hyoid bone position following treatment of class II div1 malocclusion with Farmand functional appliance]

Unlike other bones of the head and neck, hyoid bone has no bony articulations. It is connected to mandible, cranium and pharynx through muscles and ligaments. During treatment with functional appliance in patients with class II div1 malocclusion, mandible is positioned in inferior and anterior direction. Regarding the relation between hyoid and mandibular bone, alterations of hyoid bone position can be a result of functional appliance therapy. The aim of this study was to evaluate the changes of hyoid bone position following treatment with Farm and functional appliance in patients with class II div 1 malocclusion. In this before-after clinical trial, 28 patients with class II div 1 malocclusion which were under treatment with Farm and functional appliance for 11 months were selected. Facial growth in vertical, normal or horizontal direction was determined by cephalometric measurement. Data were analyzed with Paired-t test to compare the differences of mean values pre and post treatment. Variance analysis was used to compare the three growth patterns. P<0.05 was considered as the limit of significance. Hyoid bone shifted significantly forward in horizontal dimension [P<0.01] and non-significantly upward in vertical dimension. There was no significant difference among the three studied groups with respect to hyoid bone position alterations in horizontal dimension but significant difference was observed between horizontal and vertical growth pattern in vertical dimension [P<0.05]. There was significant correlation between decrease of ANB angle and forward movement of hyoid bone. Based on the results of this study, treatment with Farm and functional appliance [Fa II] leads to significant alterations in the position and anterior displacement of the hyoid bone

[Effect of different methods of enamel conditioning on bond strength of orthodontic brackets]

With the introduction of different bondable restorative materials in dentistry, various methods have been suggested to enhance the polymerization and shear bond strength of these materials. The aim of this study was to determine the effects of different methods of enamel conditioning on bond strength of orthodontic brackets and on the bracket/ adhesive failure mode. In this experimental in vitro study, brackets were bonded to thirty-six bovine incisor teeth with different protocols according to the manufacturer's instructions as follows: Group 1: conventional multistep adhesive [n=12]; Group 2: self-etching primer system [n=12]; Group 3: acid+self-etching primer system [n=12]. Specimens were loaded in a universal testing machine [Instron, Canton and Mass] and the mode of failure was recorded. Data were analyzed by ANOVA and Kruskall-Wallis tests with p<0.05 as the limit of significance. The mean shear bond strength was 11.7 +/- 4.2, 10.5 +/- 4.4, and 10.9 +/- 4.8 MPa for group 1, 2, and 3 respectively. There was no significant difference in bond strength among the three groups [P=0.800]. No significant difference was observed among the three groups with respect to residual adhesive on the enamel surfaces [P=0.554]. Based on the results of the present study, the use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in orthodontic bonding

[Deleterious Oral habits]

Oral habits are learned patterns of muscle contraction and have a very complex nature. They are associated with anger, hunger, sleep, tooth eruption, and fear. Some children even display oral habits for release of mental tension. These habits might be nonnutritive sucking [thumb, finger, pacifier and or tongue], lip biting, nail biting and bruxing events. As these habits can result in damage to dentoalveolar system, hence, dentists play a crucial role in giving necessary information to parents. This information includes relevant changes in the dentoalveolar system and the methods to stop oral habits. Also, a dentist is required to treat the ensuing malocclusion

[Four cases of angular cheilitis in orthodontic patients]

Contact dermatitis is an inflammatory reaction of the skin and mucosa to either external or internal factors. It can be divided to two forms of irritant contact dermatitis and allergic contact dermatitis. Nickel is one of the most common materials that causes allergic contact dermatitis and is widely used in orthodontic appliances. The inflammatory reaction to this metal in orthodontics is usually stomatitis and angular cheilitis is very rare. We report 4 cases of angular cheilitis in orthodontic patients and discuss about their causes and treatments

[Evaluation of condylar height and width in patients with class I and class III Malocclusions using panoramic and lateral cephalogram]

Situation of the condyle in glenoid fossa has a direct effect on the anteroposterior or vertical position of the mandible. Therefore, condylar situation and its shape has a special significance on producing facial morphology. The aim of this study was to evaluate the condylar height and width in patients with class III and class I malocclusion by using panoramic radiographs and lateral cephalograms. This study was performed on 80 pretreatment lateral cephalograms and panoramic films. Mean age in girls was 11 years and 4 months and in boys, it was 12 years and 2 months. Condylar characteristics were surveyed from the point of condylar width and condylar height. Condylar height was surveyed on the panoramic film. Condylar width was analyzed on the lateral cephalograms. Data were analyzed using t.test and ANOVA. Patients with class I malocclusion had a significantly longer condylar width relative to the patients with class III malocclusion. The condylar height in class III malocclusions was longer than class I malocclusion. This study revealed that in patients with class III malocclusion, condylar height was longer but condylar width was smaller than class I malocclusion

[Changes of oropharynx space and posterior surface of the tongue following treatment with farmand functional appliance]

During treatment with functional appliance in patient with class II division I malocclusion, mandible is postured inferiorly and anteriorly. Considering the relation between mandible with tongue and oropharynx space, functional appliance therapy can alter the tongue position and oropharynx space. This study aimed to determine the changes of oropharynx space and posterior surface of the tongue position following treatment with Farmand functional appliances in patients with class II division I malocclusions. In this clinical trial study, 28 pre and post treatment cephalometric radiographs of patients with class II division I malocclusions were investigated. The age rang of females was 10-13 years and in males it was 11-14 years. The patients were treated by Farmand functional applicne for 11 months. McNamara analysis and some linear variables were used to determine the positional changes of tongue and oropharynx space. Paired-t test was used to compare the pre and post treatment differences of mean values. Variance analysis was used to compare the growth patterns of the patients. Tongue moved significantly forward [p<0.001] but non-significantly downward. Oropharynx space increased significantly in sagittal dimension [p<0.001]. There was a significant correlation between decrease of ANB angle with forward movement of tongue [p<0.05] as well as with the increase in extent of oropharynx space in the sagittal dimension [p<0.05]. Treatment with Farmand functional appliance showed significant alteration in tongue position and as a result, increased the extent of oropharyngeal space