Journal of Dental Medicine

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Statement of Problem: Ultrasonic Scaling is one of the main sources of producing infected aerosols in dentistry. These aerosols are able to spread pathogens such as microorganisms associated with tuberculosis, conjunctivitis, influenza and other respiratory diseases, herpetic and other skin diseases, ADIS and hepatitis B.
Purpose: The aim of this study was to investigate the clinical effectiveness of an aerosol- reduction device attaching to ultrasonic scaler handpiece.
Materials and Methods: In this experimental study 18 patients participated. Randomly, mandibular and maxillary quadrants of one side, in each subject, were scaled using an ultrasonic scaler with aerosol-reduction device for 5 minutes. After 30 minutes, another quadrant was scaled by ultrasonic scaler without aerosol- reduction device. In order to determine the effectiveness of aerosol- reduction device, blood agar plates attached to the surgical mask of the operator, 30 cm far from the patient's mouth, were incubated in 37°c for three days and the colonies were counted. Median, Interquartile eange and Wilcoxon test, at the 0.05 level of significance, were used to analyze the data.
Results: The median and interquartile range for the number of colony forming units (CFUS) without aerosol- reduction device was 17.5 (8, 24), while the median for the number of CFUS when using aerosol-reduction device was 0 (0, 1), indicating significant statistical difference (PO.001)

Conclusion: The aerosol- reduction device significantly reduces the amount of aerosols produced during ultrasonic scaling.

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 Statement of Problem:The choung osteotomy (Intraoral Vertico- Sagittal Ramus Osteotomy) has developed since 1992 in the treatment of mandibular prognathism. In IVSRO, osteotomy plane is theoretically parallel to the original sagittal plane and thereby attempting to decrease the incidence of condylar dispacement. This osteotomy designed additionally to decrease neurosensory disturbances.
Purpose: The aim of this study was to evaluate the incidence of neurosensory deficit and condylar displacement with IVSRO and Sagittal Split Ramus Osteotomy (SSRO).
Materials and Methods: In this study, mandibular set back surgery was accomplished upon 7 patients by choung osteotomy. In addition to choung osteotomy, in 2 patients Lefort 1 osteomy was performed for maxillary protrusion and for 2 other patients, chain surgery was performed. Variables such as the neurosensory disturbances of inferior alveolar nerve and condylar displacement following choung osteotomy were investigated. All the patients were followed up one year after osteotomy. OPG, Lateral Cephalogram and Submentovertex radiographies were take pre and postoperatively for all patients.
Results: No statistically significant differences were found in condylar displacement (P>0.5). However, Mc Nemar analysis showed significant difference of neurosensory deficit between IVSRO and SSRO (P=0.001).
Conclusion: It is suggested that choung osteotomy is a safe procedure for mandibular surgery.

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Background and Aim: In recent years, CT scan has become available as an alternative to conventional radiography. To date, the utility of Waters view in detecting midface fractures has been rarely evaluated. The aim of this study was to compare the diagnostic accuracy and reliability of Waters radiography with CT scan in detecting midface fractures.

Materials and Methods: In this tests evaluation study, waters view and CT scan were performed for 42 patients with midface fracture admitted to maxillofacial surgery department of Shariati hospital. All images were observed and interpreted by an oral and maxillofacial radiologist and an oral and maxillofacial surgeon. Sensitivity, specificity and reliability for Waters view in detecting midface fractures were assessed by Cohen’s kappa test.

Results: Sensitivity and specificity for Waters view in detection of midface fratures by the radiologist were 31.79% and 95.35% and by the surgeon were 29.59% and 93.75% respectively. The highest reliability in CT scan and Waters view (in nasal fractures) by the radiologist was 66.67% and was 58.33% by the surgeon in buttress of zygoma. The highest agreement rate between the radiologist and the surgeon for CT scan was in zygomatic arch (78.95%) and for Waters view was in nasal fracture (62.5%).

Conclusion: Based on the results of this study, the specificity of Waters view is sufficient to diagnose fractures of lateral orbital wall, infraorbital rim, orbital floor, zygomatic arch, frontozygomatic suture, lateral wall of maxillary sinus and Lefort II fracture. The specificity is not sufficient to diagnose fractures of medial orbital wall and anterior, posterior and medial wall of maxillary sinus. Detection of these midface fractures needs other conventional radiographies or CT scan.

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Background and Aim: The structural rehabilitation of a pulpless tooth is critically important to ensure a successful restorative outcome following endodontic treatment. A post and core is often indicated for the retention and reinforcement of the final restoration. But, the clinical situation is significantly challenging if the root exhibits immature development or there is a thin root wall that can compromise the prognosis for a long- term successful treatment. The purpose of this in vitro study was to evaluate different methods of intraradicular reinforcement in structurally compromised roots.

Materials and Methods: In this experimental study, seventy two extracted intact maxillary central incisors with similar size, shape and root anatomy were selected. After root canal therapy in 60 teeth, an acrylic laboratory bur was used to thin the cervical area and simulate the thin dentinal walls of immature teeth. The preparation was performed through the palatal access and extended 5mm apical to CEJ. The remaining 12 teeth remained unprepared to serve as positive control group. Cases were randomly divided into six groups of 12 teeth each and restored as follows. In the 12 cervically unprepared teeth (positive controls) the composite resin with dentin bonding agent (DBA) was placed in access cavity and cured for 120 seconds. This technique was also applied to other groups when the access was restored with composite. In the second group, the access cavity was restored with composite only to the level of CEJ. In the third group the cervically prepared teeth were reinforced with cement resin (Enforce) and a prefabricated post was placed in 5mm apical to the CEJ. In the fourth group, the cervically prepared teeth were reinforced with composite resin and DBA by a clear plastic post. In the fifth group the cervically prepared teeth were reinforced with composite resin and dba and a cast post. In the sixth group the cervically prepared teeth were restored with composite resin and dba with a prefabricated post. All of the specimens were mounted by rubberized technique and tested in the Instron universal testing machine. The fracture loads in samples were analyzed with ANOVA and Duncan tests with p<0.05 as the limit of significance.

Results: Significant differences in fracture resistance were observed between the first and second groups compared with others. The highest fracture resistance values were recorded for first group while the lowest were registered for the second group. Fracture resistance of the third, fourth and fifth groups had no significant statistical differences with others and fracture resistance of sixth group was the highest with significant difference (P<0.05).

Conclusion: From this study, it may be concluded that the use of a dba and a composite resin in thin-walled roots reinforces the immature teeth and facilitates the use of post.

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Background and Aim: Microleakage has been always a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. The aim of this study was to investigate the effect of flowable and dual-cure resin composite liners on gingival microleakage of packable resin composite restorations.

Materials and Methods: Sixty Class II cavities with cervical margins 1 mm below the CEJ were prepared in 30 extracted human molars. The teeth were randomly divided into five groups of 12 each. In control group, each tooth was restored incrementally with Tetric Ceram composite without applying any liner. In the second and forth groups, flowable materials- Tetric Flow and dual-cure composite resin cement Relay X ARC were placed respectively as a 1-mm thick gingival increment and cured before the resin composite restoration, whereas, in the third and fifth groups liners were cured with the first increment of packable composite.The restored teeth were stored for one week in distilled water at 37⁰C, and thermocycled between 5⁰C and 55⁰C, sealed with nail varnish except the tooth - composite interface in cervical restoration margins and immersed in 2% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope with 28x magnification. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests with p<0.05 as the level of significance.

Results: The results of this study indicated that there were significant statistical differences between control - cured flowable liner, control-flowable liner without separately curing, control-cured dual cure composite resin cement groups.However there were no significant differences between dual-cure composite resin cement without separately curing-control,cured flowable liner-cured dual cure composite resin cement, flowable liner without separately curing-dual cure composite resin cement without separately curing groups.

Conclusion: The results of this study indicated that none of techniques could thoroughly eliminate microleakage in gingival floor, however the effect of flowable or a dual-cure liner on reducing the gingival microleakage was found to be statistically significant in tested restorative material.

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Background and Aim: Fractured anterior teeth can be restored by adhesive bonding of the separated fragment to the remaining tooth structure. This invitro study evaluated the force required for fracture of rebonded fragments which were dried and rewetted for various time intervals prior to bonding.

Materials and Methods: One hundred and eight human mandibular incisors were selected and were divided into 9 groups and then were fractured. The fragments were stored in air at room temperature and ambient humidity. They were air dried for 30 minutes in group 1, 2 and 3,  6 h in group 4 and 5,  24 h in group 6 and 7, and 3 days in groups 8 and 9. The apical parts of the fractured teeth were stored in water.After storage in air, each fragment in group 1 was bonded to the remaining apical tooth structure with a bonding agent and flowable composite.In groups 2, 4, 6 and 8 after air drying the fragments were stored in water for 30min. The time of storage in water in groups 3, 5, 7, 9 was 24 hours. Then each fragment was bonded to the apical part structure. The mean force required for fracture was measured by a mechanical testing machine. One way ANOVA and Tuckey tests were used for analysis.

Results: There were statistically significant differences between different groups (p<0.001).The highest and lowest force required for fracture belonged to groups 3 and 8 respectively. The force required for fracture in group 1 was lower than group 2, 3, 5 and 7 and 9 and more than groups 4,6 and 8 with significant differences.While there were no significant differences among groups 3, 5, 7, 9 and 4, 6, 8 the force required for fracture in groups 2, 3, 5, 7 and 9 was more than 4, 6, 8 with significant differences.

Conclusion: This research revealed that the force required for fracture was affected by air storage of fragments prior to bonding. Also showed that with an increase in duration of drying the force required for fracture decreased and after a period of time it becomes steady. This study showed that in order to increase the fracture strength after air drying the fragment should be immersed in water for at least 24 hours prior to bonding.

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Background and Aim: As composite-dentin bond strength is affected by cavity preparation and the bond strength of composite resin to new and used bur prepared dentin has not yet been evaluated, this study evaluated the effects of cutting dentin with different cutting efficacy (new and used) of burs on composite-dentin shear bond strength using self-etching primer bonding system and total etching bonding system.

Materials and Methods: Sixty caries free human 3rd molar were sectioned in occlosal surface to expose dentin, then polished with silicon carbide paper and randomly divided into four groups. Each group was prepared in a depth of 0.5mm of dentin, using new diamond bur, or used diamond bur. To change into a used bur, each new rough diamond bur had to work on bovine enamel for 30 minutes, under a load of 150g. Then, each group was bonded, using a total etch adhesive (single Bond) or a self etch adhesive (clearfil SE Bond) So there were 4 groups : 1-SE Bond, New bur 2-SE Bond , used bur 3-Single Bond , New bur 4-Single Bond, used bur. Similar composite capsules(Filtek Z250) were bonded to dentin surface and cured. specimens were stored in physiologic saline for 48h at 37⁰ c , then put under shearing load to define composite - dentin shear bond strength. Results were interpreted via statistical analysis (T-test & two - way variance).

Results: Shear bond strength of each group was as follows: 1-(27.3Mpa), 2-(33.5Mpa), 3-(16.9Mpa) 4-(19.3Mpa). Statistical analysis proved that shear bond strength of used diamond bur prepared groups (2,4) was more than new diamond bur prepared ones (1,3). This statistical difference, specially, was seen between SE Bond groups (1,2) but not between single Bond groups (3,4). Also, shear bond strength of (SE Bond) bonded groups (1,2) were more significantly than (single Bond) bonded ones (3,4).

Conclusion: This study show that Bur cutting efficiency influences composite - dentin shear bond strength especially when the adhesive is SE Bond (used bur> new bur) Also type of adhesive affects on composite - dentin shear bond strength. (SE Bond > Single Bond).

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  Background and Aims: Electric pulp tester is a valuable instrument to examine tooth’s pulp vitality. There is no agreement about the response of immature teeth to electric pulp tester and the reason is expressed as the failure of nerve fibers’ development. The aim of this study was to investigate the effect of patient’s age on the tooth response to electric pulp tester.

  Materials and Methods: In this cross-sectional study, 300 maxillary central permanent teeth in 150 volunteers were examined by using electric pulp tester. The volunteers were classified in 5 age groups of 7-8, 9-10, 11-12, 13-4, and 30-35 and teeth lacking sound and healthy pulp were excluded. Data were analyzed using SPSS-16 software, one-way analysis of variance, and Tukey post hoc test.

  Results: The average response to electric pulp tester in age groups of 7-8, 9-10, 11-12, 13-4, and 30-35 years old were 2.9±0.1, 2.8±0.1, 2.3±0.1, 2.2±0.1 and 1.8±0.1 ,respectively. This indicated that by increasing teeth age, they responded to lower level of electric pulp tester. In subjects less than 14 years old, there was no significant difference between neighboring groups (P=0.3) however, a significant difference was observed between subjects less than 14 years old and adults (P<0.001).

  Conclusion: This study showed that immature teeth responded at higher levels to electric test however, all teeth responded to electric pulp tester.

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Background and Aims: Temporomandibular joint disorders (TMDs) are one of the most common causes of the patient's referral to dental clinics. Considering the role of related factors in its creation, the purpose of this study was to investigate the relative frequency of factors related to temporomandibular disorders in patients aged 20 to 50 years referred to dental clinics in Isfahan in 1397. Materials and Methods: In this descriptive and analytical study, 324 patients referred to Isfahan dental clinics in 1397 were randomly included. Factors related to TMD and demographic factors of patients were recorded with clinical examination by a trained dentist and self-declaration of patients in the data collection form. The frequency and relevance were analysed by SPSS 22 software and chi-square, fisher and logistic regression statistic tests. Results: At least one of the TMD related factors was present in 40.7% of the subjects, which the most common factors related to TMD was posterior edentulousness (49.7%). History of jaw dislocation was more common in men (P=0.014) and the frequency of posterior edentulousness was more common in in women (P=0.003). As the age increased, the frequency of posterior edentulousness (P=0.000) and earache (P=0.009) increased. The frequency of posterior edentulousness was higher in housekeepers (P=0.000), the frequency of earache was higher in employees (P=0.005) and the history of jaw dislocation was higher in self-employed persons (P=0.047).