Journal of Dental School
Volume:38 Issue: 2, Spring 2020

Several tools have been introduced to increase the accuracy of dental implant placement. This study aimed to design and fabricate a new surgical guide for dental implant placement in partial edentulism and assess its efficacy.

The designed aluminum surgical guide has eight accessories and one graded rocket. The accessories have 6, 7, 8 and 9 mm diameter, and 6 mm height. Each accessory pair has a hole for passage of 2 mm and 2.8 mm drills. The efficacy of the designed surgical guide was tested by placement of 15 dental implants in jaw models. Cone-beam computed tomography (CBCT) scans were obtained, and analyzed to assess the implant-tooth and inter-implant distances and inter-implant angulation using NNT Viewer software. Data were analyzed using one-sample t-test. P<0.05 was considered significant.

A significant difference was noted between the planned and actual values in the implant-adjacent tooth mesiodistal distance (P<0.001), and inter-implant distance (P=0.005). However, no significant difference existed in inter-implant angulation (P=0.073). The mean implant-tooth and inter-implant distances, and the mean inter-implant angulation were 0.284±0.199 mm, 0.0350±0.176 mm, and 3.883±4.20°, respectively. Conclusion The designed surgical guide had high accuracy in achieving optimal inter-implant angulation and linear implant-adjacent tooth and inter-implant distances, and the obtained mean values were clinically acceptable.

The aim of this study was to evaluate the validity and reliability of a newly designed cephalometric analysis program (Hexagon software) in comparison with manual and digital (Dolphin software) tracings.

Pre-treatment lateral cephalometric radiographs of 32 adult patients between 18 to 41 years (10 males and 22 females, mean age of 22.78 ± 5.17 years) were randomly chosen. For each radiograph, 10 angular and 6 linear measurements were calculated using three different methods (manual and digital using two different software programs). The cephalograms were manually traced using acetate paper, x-ray light box, 0.3 mm HB pencil, ruler, and protractor. For digital tracing, cephalograms were traced with Dolphin vertion-10 (USA) and Hexagon (Iran) software programs. All the analyses were performed by one operator 2 times with at least a four-week interval between the two tracings. The intra-class correlation coefficient (ICC) was used to evaluate the intra-examiner agreement, while the differences between the methods were analyzed using paired t-test, and ANOVA.

The intra-examiner repeatability of all measurements in all three tracing methods showed high agreement. Differences in measurements between the two software programs and hand tracing were not statistically significant for any of the cephalometric parameters (P>0.05).

The results demonstrated that the accuracy of cephalometric tracing by the Hexagon software was similar to the Dolphin software, and the manual tracing technique.

Interim restorations play a critical role in success of restorative treatments. However, they need to preserve their integrity in the oral environment. Microhardness is an important factor in preservation of the integrity of restorations. This study aimed to compare the microhardness of three interim restorative materials namely polyether ether ketone (PEEK), an indirect composite, and polymethyl methacrylate (PMMA).

This in vitro, experimental study evaluated 10 disc-shaped specimens, measuring 15 mm in diameter and 1 mm in thickness, fabricated from PEEK, an indirect composite, and PMMA. The microhardness of the specimens was measured at three points of each specimen using the Vickers’ hardness test before and after water storage for 30 days. Data were analyzed using repeated measure ANOVA, one-way ANOVA and Tukey’s test.

Indirect composite showed maximum microhardness, which was significantly higher than that of the other two materials (P=0.001). However, no significant difference was noted in microhardness of PEEK and PMMA (P=0.33). The microhardness of the materials did not significantly change after 30 days of water storage (P=0.06). Conclusion The microhardness of indirect composite was higher than that of PEEK and PMMA. Also, 30 days of water storage had no significant effect on microhardness of the materials.

Ameloblastoma is an odontogenic neoplasm with locally aggressive behavior. Fas and FasL play important roles in apoptotic pathways.The aim of this studywas to determine the possible role of expression of apoptotic pathways (Fas and FasL) in human ameloblastomaand the relationship of apoptosis with the clinical biological characteristics of ameloblastoma.

Inthis descriptive retrospective study,we investigated the anti-Fas and anti-FasLantibody expression in 11 dental follicles and 56 ameloblastomaspecimens (35 conventional, 15 unicystic and 6 ameloblastic carcinoma samples)by immunohistochemical(IHC) staining and polymerase chain reaction(PCR).The percentage of positive cells was calculated by using the Mann-Whitney U test and Kruskal-Wallis test.Results The rate of expression of markers was significantly lower in dental follicles than all subtypes of ameloblastoma (P=0.01 forFas, and P=0.0001 for FasL). The FasL proportional score was significantly higher in conventional ameloblastoma than in unicysticameloblastoma and ameloblasticcarcinoma(P=0.003). There was no significant relationship between the type of ameloblastoma and expression of Fas.

This study shows that the process of apoptosis in ameloblastomais a sign of behavioral change in odontogenic epithelial cells especially in conventional ameloblastomaand that the apoptoticfactors maynot play an effective role in the malignancy of ameloblastoma.

Bleaching agents can change the organic and mineral contents of the tooth structure. The aim of this study was to evaluate the effects of two remineralizing agents on surface roughness of bleached enamel.

In this experimental study, 24 premolars were collected. The testing area was a window measuring 3 × 4 mm. First the surface roughness of specimens was measured by atomic force microscopy (AFM). Then, the teeth were bleached. Surface roughness was measured again. Specimens were randomly divided into 3 groups. No remineralizing agent was applied in the control group (A). Casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and Remin-Pro were used in groups B and C, respectively. After 15 days, the surface roughness was measured. The changes in surface roughness were analyzed by paired t-test, and comparison between the groups was done by the Welch and Games-Howell post hoc tests.

The surface roughness increased after bleaching (P<0.000). Surface roughness in groups B (P=0.03) and C (P=0.04) was significantly lower than that in group A. There was no significant difference in the level of surface roughness reduction between groups B and C. The Welch test revealed that the mean change in surface roughness values after remineralization in groups B and C was significantly higher than that in group A (P=0.001 and P=0.002, respectively). The difference between groups B and C was not significant (P=0.97).

CPP-ACP and Remin-Pro reduce the surface roughness of bleached enamel more effectively than the saliva.

Considering the fact that lack of knowledge about medical emergencies is associated with serious consequences for patients, the present study was conducted to compare the knowledge level of dental students and general dentists about medical emergencies.

This descriptive cross-sectional study was performed on senior dental students of Babol University of Medical Sciences in the academic year 2014-2015 and dentists practicing in Babol city. Data were collected by a questionnaire, which included questions regarding the demographic information of participants, their educational experience in this field, and knowledge level. Data were analyzed by t-test, Chi-square test, and Pearson and Spearman’s correlation coefficients.

Fifty dental students with a mean age of 26.78 years and 50 dentists with a mean age of 37.36 years were evaluated. The mean experience of dentists was 7.46 years. Totally, 11 students (22%) and 39 dentists (48%) had encountered medical emergencies in the past year. Of all, 16 students (32%) and 12 dentists (24%) had received the necessary training in their university. The mean knowledge score was statistically similar in both groups (5.46±1.07 and 5.76±1.30 in students and dentists, respectively; P=0.2). The level of knowledge of 48% of dental students and 44% of dentists was poor; 8% of dentists had very good knowledge level.

The knowledge of dentists and senior dental students of Babol regarding medical emergencies was similar and generally not satisfactory.

Restoration of severely damaged endodontically treated anterior teeth typically poses a challenge. Specific indication of post-retained restorations in such teeth has reasonably been questioned because of the potential tooth structure weakening. The present study aimed to describe a modified conservative endocrown (modified refers to intracanal extension while conservative refers to preparation at the finish line) to rehabilitate severely damaged anterior teeth.

Endodontically treated lower right central incisor had inadequate remaining tooth structure and restored by endocrwn restoration as a definitive treatment and followed for 30 month.

Considering the clinical outcome after 30 months of follow-up, it seems that this specific type of endocrown could efficiently serve as a conservative treatment approach to restore endodontically treated anterior teeth.

Lesch-Nyhan syndrome is a rare inherited disorder associated with self-harming behaviors, delayed mental and motor development, and disturbances such as dysarthria, choreoathetosis, and spasticity. Severe inflicted behaviors in Lesch-Nyhan syndrome often include chewing and biting of the lips or fingers, which often require management. Techniques to deal with these behaviors include using appliances that restrict the behavior or ultimately extracting the teeth.

This case report presents a 6-year-old child with Lesch-Nyhan syndrome and self-mutilation. He had chronic wounds in his buccal mucosa due to severe biting. Two acrylic devices with anterior and posterior bite plates were designed for the maxillary and mandibular teeth. At the follow-up visits, the wounds had been healed, but due to shedding of the primary teeth, and poor patient cooperation, the appliance design was slightly changed. The design of the device used for the patient inspires similar devices for patients with self-mutilation behaviors.

Early diagnosis and management of patients suffering from self-injurious behaviors may improve oral health-related quality of life of these patients. Acrylic appliances seem to be effective to minimize injury and to enhance fast healing of oral lesions.