Frontiers in Dentistry
Volume:12 Issue: 4, Apr 2015

Pneumatized articular eminence or tubercle (PAT) is an air cell cavity in the zygomatic process of the temporal bone. Pneumatization of articular eminence may be seen incidentally on panoramic radiographs (PR) as a unilocular or multilocular, radiolucent defect. The aim of this study was to assess the prevalence and the pattern of PAT on PR in an Iranian population. A total of 3,098 PRs belonging to 1,735 females and 1,363 males were retrospectively investigated for the presence and radiographic features of PAT. All PRs were taken for routine dental examination. Chi square test, univariate odds ratio (OR) and corresponding 95% confidence interval (95% CI) and binary logistic regression were used for statistical analysis. PAT was found in 2.1 % of cases including 41 females and 23 males (with a mean age of 33.23±12.43 and 35.64±13.24 years, respectively, range 19-69 years). There were 40 unilateral and 24 bilateral cases (a total of 88 PAT) in this study including 49 unilocular and 39 multilocular cases. There was no significant difference in PAT between males and females or different age groups. (P>0.05 and all 95% CI included 1). Binary logistic regression indicated that there was no relationship between the presence of PAT and age or sex. Knowledge about this anatomical variation is helpful for clinicians who are planning to perform temporomandibular joint surgery. They should asses the radiographic imaging thoroughly before the surgery. It can also provide valuable information to understand the differential diagnosis of pathological entities in this region.

Correct determination of working length is an important step for success of endodontic therapy. Conventional radiography has limitations in providing the accurate location of apical foramen. For this reason, electronic apex locators (EALs) were developed to shorten the treatment time and decrease the radiation dose.The aim of this study was to evaluate the accuracy of Root ZX EAL for working length determination in primary anterior teeth. In this in-vitro study, 50 extracted primary anterior teeth with root resorption were selected with no obstructed canals or history of previous root canal therapy. Working lengths were measured by direct observation of actual length (AL), radiography and Root ZX EAL. A variation of ±0.5 mm from the AL was considered acceptable. The results were analyzed statistically using paired t test and interclass correlation coefficient (ICC) at 0.05 level of significance. Considering an acceptable 0.5 mm margin from AL (direct measure-ment), the accuracy of Root ZX EAL and radiography was found to be 86% and 76%, respectively. Absolute value of error from AL was significantly lower for ZX compared to radiography (P˂0.001). Interclass correlation comparing both radiography and Root ZX with AL showed strong correlations. Root ZX EAL can be used as a reliable tool for obtaining root canal length in primary anterior teeth with resorption.

One major drawback of orthodontic treatment is its long duration due to slow tooth movement and the pain at the onset of treatment following application of forces. There is controversy regarding the efficacy of laser for decreasing the treatment time and pain of orthodontic treatment. The purpose of this study was to investigate the effect of low level diode laser on the rate of orthodontic tooth movement and the associated pain. In this double blind randomized controlled clinical trial, 12 orthodontic patients referring to Shahid Beheshti School of Dentistry for first premolar extraction were randomly selected and allocated to gallium aluminum-arsenide laser (Ga,Al,As diode laser, 880 nm, 100 mW, 5 j/cm2, 8 points, 80 seconds, continuous mode) or control group. The patients initially underwent leveling and alignment using the sectional system. Force (150 gr) was applied to each canine tooth via sectional closing loops. The loops were activated every month. The rate of tooth movement and pain were monitored over the treatment period and recorded on days 1, 3, 7, 30, 33, 37, 60, 63 and 67. Two-way ANOVA was used for comparison of groups. There was no significant difference in terms of tooth movement and pain scores between the irradiated and non-irradiated sides at any time point (P>0.05). Although laser enhanced orthodontic tooth movement in the upper jaw, we failed to provide solid evidence to support the efficacy of laser for expediting tooth movement or reducing the associated pain.

Purpose of Study: The purpose of this study was to evaluate the effect of salivary pH on the shear bond strength (SBS) of orthodontic brackets to tooth surface. Eighty intact premolars were randomly divided into four groups of 20. After bonding a bracket on each tooth, the groups one to four were stored in artificial saliva at a pH of 3.8, 4.8, 5.8, and 6.8, respectively for two months. The artificial saliva solutions were refreshed weekly. Each tooth was then embedded in an acrylic block so that the crown was exposed and its buccal surface was parallel to the direction of the force during SBS testing. All brackets were debonded using Dartec universal testing machine, and the mean values of SBS in different groups were compared using one- way analysis of variance (ANOVA). The mean SBS value in group 1 (pH 3.8) was significantly lower than that in other groups (P value<0.05). The differences between other groups were not significant (P>0.05). Decreased salivary pH, due to poor oral hygiene, and/or frequent consumption of acidic beverages, may be responsible for orthodontic bracket bond failure.

Temporomandibular dysfunction (TMD) is a group of disorders in the facial region and temporomandibular joint (TMJ). Biomarkers are assumed to play a role in pain and early detection of destruction. The aim of this study was to compare the saliva and serum antioxidant levels in patients with TMD and healthy subjects. This case-control study was conducted on 28 TMD patients without pain, 28 TMD patients with pain and 28 healthy controls. The total antioxidant capacity of saliva and serum of patients was measured. Data were analyzed using ANOVA and Tamhane’s test. The mean (±SD) total antioxidant capacity of serum (plasma TAC) was 0.8900 (±0.11627) mmol/L in TMD patients with pain, 1.2717 (±0.18711) mmol/L in TMD patients without pain and 1.7500(±0.18711) mmol/L in the control group. Based on ANOVA, the difference in this regard among the 3 groups was statistically significant (P=0.000). The mean salivary TAC was 1.34 (±0.06721) mmol/L in TMD patients with pain, 1.42 (±0.16677) mmol/L in TMD patients without pain and 1.35 (±0.11627) mmol/L in the control group. The difference in this respect among the 3 groups was not significant (P>0.05). The mean plasma TAC in TMD patients with/without pain was significantly lower than that in the control group but no significant difference was detected in salivary TAC among the three groups.Key words: Antioxidants; Saliva; Serum; Temporomandibular joint disorders; Oxidative stress

Headgears are among the effective orthodontic appliances to achieve treatment goals. Unilateral molar distal movement is sometimes needed during an orthodontic treatment, which can be achieved by an asymmetric headgear. Different unilateral headgears have been introduced. The main goal of this study was to analyze the force system of unilateral expanded outer bow asymmetric headgears by the finite element method (FEM). Six 3D finite element models of a mesiodistal slice of the maxilla containing upper first molars, their periodontal ligaments (PDLs), cancellous bone, cortical bone, and a cervical headgear with expanded outer bow attached to maxillary first molars were designed in SolidWorks 2010 and meshed in ANSYS Workbench ver. 12.1.The models were the same except for the degree of outer bow expansion. The outer bow ends were loaded with 2-Newton force. The distal driving force and the net moment were evaluated. A decrease in the distalizing force in the normal side molar from 1.69 N to 1.37 N was shown by increasing the degree of unilateral expansion. At the same time, the force increased from 2.19 N to 2.49 N in the expanded side molar. A net moment increasing from 2.26 N.mm to 4.64 N.mm was also shown. Unilateral outer bow expansion can produce different distalizing forces in molars, which increase by increasing the expansion.

Providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force.The purpose of the present study was to evaluate the effect of four zirconium surface treatment methods on shear bond strength (SBS) of orthodontic brackets. One block of zirconium was trimmed into four zirconium surfaces, which served as our four study groups and each had 18 metal brackets bonded to them. Once the glazed layer was removed, the first group was etched with 9.6% hydrofluoric acid (HF), and the other three groups were prepared by means of sandblasting and 1 W, and 2 W Er:YAG laser, respectively. After application of silane, central incisor brackets were bonded to the zirconium surfaces. The SBS values were measured by a Dartec testing machine with a crosshead speed of 1 mm/min. The highest SBS was achieved in the sandblasted group (7.81±1.02 MPa) followed in a descending order by 2 W laser group (6.95±0.87 MPa), 1 W laser group (6.87±0.92 MPa) and HF acid etched group (5.84±0.78 MPa). The differences between the study groups, were statistically significant except between the laser groups (P < 0.05). In terms of higher bond strength and safety, sandblasting and Er: YAG laser irradiation with power output of 1 W and 2 W can be considered more appropriate alternatives to HF acid etching for zirconium surface treatment prior to bracket bonding.

Dental caries are common and have a high incidence among popula-tions. Radiographs are essential for detecting proximal caries. The best technique should be recognized for accurate detection of caries.The aim of this study was to compare the accuracy of detection of proximal caries using intra oral bitewing, extra oral bitewing, improved interproximal panoramic, improved orthogonality panoramic and digital conventional panoramic radio-graphs. In this descriptive cross sectional study, 100 extracted human teeth with and without proximal caries were used. Intra and extra oral radiographs were taken. Images were evaluated and scored by two observers. Scores were compared with the histological gold standard. The diagnostic accura-cy of radiographs was assessed by means of receiver operating characteristic (ROC) curve analysis (P<0.05). Microscopic evaluation of proximal surfaces revealed that54.8% of the surfaces were sound and 45.2% were carious (with different depths).The differences inthe area under the ROC curve (Az value)among the five techniques were not statistically significant. Improved interproximal panoramic and extra oral bitewing radio-graphs were superior to conventional panoramic radiography for detection of proximal caries ex vivo and should be considered for patients with contraindications for intra oral radiographs.

The aim of this study was to investigate the displacement and stress distribution during surgically assisted rapid maxillary expansion under different surgical conditions with tooth- and bone-borne devices. Three-dimensional (3D) finite element model of a maxilla was constructed and an expansion force of 100 N was applied to the left and right molars and premolars with tooth-borne devices and the left and right of mid-palatal sutures at the first molar level with bone-borne devices. Five CAD models were simulated as follows and surgical procedures were used: G1: control group (without surgery); G2: Le Fort I osteotomy; G3: Le Fort I osteotomy and para-median osteotomy; G4: Le Fort I osteotomy and pterygomaxillary separation; and G5: Le Fort I osteotomy, para-median osteotomy, and pterygomaxillary separation. Maxillary displacement showed a gradual increase from group 1 to group 5 in all three planes of space, indicating that Le Fort I osteotomy combined with para-median osteotomy and pterygomaxillary separation produced the greatest displacement of the maxilla with both bone- and tooth-borne devices. Surgical relief and bone-borne devices resulted in significantly reduced stress on anchored teeth. Combination of Le Fort I and para-median osteotomy with pterygomaxillary separation seems to be an effective procedure for increasing maxillary expansion, and excessive stress side effects are lowered around the anchored teeth with the use of bone-borne devices.

This case report describes the treatment of two immature maxillary central incisors in a 7-year-old female patient. She suffered complicated crown fracture because of trauma, and the root formation was incomplete. White mineral trioxide aggregate (MTA) was selected as the pulp-capping material after cervical pulpotomy to preserve the pulp tissue vitality and achieve maturogenesis. Follow-up evaluations showed successful treatment in terms of preservation of pulp vitality and demonstrated marked continuous physiological root development. During 10 years of follow-up, both teeth were clinically asymptomatic, and radiographic evaluations showed apparent root regeneration with apical root-end closure without pulp or periapical pathosis.