مجله دانشکده دندانپزشکی مشهد
سال چهل و پنجم شماره 4 (پیاپی 119، زمستان 1400)

Occlusion stability following orthodontic treatments is a daunting challenge for orthodontists and this stability is maintained using retainer devices after the active phase of treatments. Although Hawley retainer has a wide application in retention objectives, the use of Essix retainers has been on a rise in recent years. The present study aimed to compare occlusal settling in orthodontic patients after using Essix and Hawley retainers using the T-Scan III technique for bite recordings in the retention period.

In this observational-analytical trial, 46 orthodontic patients (24 for Hawley and 22 for Essix retainers) were selected at the end of the active phase of the treatment. The patients used Hawley and Essix retainers at both jaws for 1 year, and the occlusal settling (occlusal contacts) was recorded by the T-Scan III technique at the initial time (T0), as well as 6 months (T1) and 1 year (T2) after retention. The intragroup and intergroup changes (percent) that occurred in occlusal contacts in different time intervals were statistically analyzed by paired t-test and student t-test, respectively.

In the Hawley retainer group, the occlusal contacts significantly increased in the posterior teeth (7.708±13.5; P=0.008) and significantly decreased in the anterior teeth (7.416±11.791; P=0.005). On the other hand, in the Essix retainer group, occlusal contacts decreased in the posterior teeth (10.19±14.884; P=0.008) and significantly increased in the anterior teeth (10.381±18.591; P=0.005). 

AS evidenced by the obtained results, both Hawley and Essix retainers caused changes in the occlusal contacts and relative vertical movement of posterior teeth in the patients after 6 months and 1 year of retention, compared to the initial time. Nonetheless, Hawley retainer seemed to ring about more posterior changes (settling) than Essix retainer. Due to the increase in posterior tooth contact and the decrease in anterior tooth contact with the use of Holly retainer, this retainer can be a better choice in deep bite cases. Furthermore, due to the reduction of posterior contacts in the first 6 months in the Essix license plate, it is suggested that the full-time use of this retainer be shortened.

Multiple sclerosis is a neurodegenerative disease that has multiple orofacial manifestations. Its complications could make difficulties in the ability to keep oral health and patients' cooperation in the dental office. This study aimed to assess the knowledge and practice among general dentists concerning multiple sclerosis in Yazd, Iran, in 2020.

This cross-sectional descriptive study randomly selected 105 general dentists working in Yazd, Iran. A researcher-made questionnaire was used to seek such information as demographic characteristics, knowledge (13 questions) and practice (10 questions) among general dentists concerning dental treatments in patients with multiple sclerosis. The data were analyzed in SPSS software (version 17) using t-test and Pearson's correlation coefficient. 

Of 105 participants 46.7% were male and 53.3% were female. Out of 105 dentists, the majority (53.3%) of the cases were male. The mean±SD age and work experience of the participants were 30.09±4.47 and 4.89±3.59 years, respectively. Moreover, the mean scores of knowledge and practice were determined at 14.39±2.54 (maximum possible score=26) and 12.45±2.16 (maximum possible score=20), respectively. There was a significant and direct relationship between knowledge and practice (r=0.232; P=0.022). Knowledge and practice did not show a significant relationship with gender, age group, and work experience (P>0.05).

According to the results, dentists had low to moderate knowledge and practice levels regarding patients with multiple sclerosis. Therefore, it is necessary to implement educational programs with interdisciplinary collaboration to promote the knowledge and practice of general dentists.

Multiple sclerosis (MS) is an inflammatory disease that destroys neurons and exerts detrimental effects on oral health, apart from its negative physical and psychological consequences. Although there is a bulk of research on oral health in patients with MS, no study has evaluated the quality of life associated with oral health in these patients. Therefore, the current study aimed to assess oral health-related quality of life in patients with MS.

This case-control study was conducted on 103 patients with MS and 103 healthy participants. The subjects in both groups completed standardized Oral Health Impact Profile (OHIP) questionnaires and assessments of indicators related to oral health behavior. Caries index was also measured and recorded for the subjects in both groups. Finally, the data were analyzed in SPSS software using linear regression, T-test, Mann-Whitney tests.

The oral health-related quality of life was statistically significantly lower in patients with MS, as compared to that in the control group (P=0.032). Moreover, the caries index score was significantly higher in patients with MS (P=0.025).

As evidenced by the obtained results, oral health-related quality of life in patients with MS, who have more dental caries, is not significantly different from that in healthy individuals. Further qualitative studies are needed to shed more light on the problems posed to these patients.

Porcelain veneer fracture is one of the problems of zirconia restorations. Intraoral repair of composites can be an alternative for restorations. A stable bond between the composite and zirconia is necessary for the durability of the restoration. The present study aimed to evaluate the effect of different surface treatments and two porcelain repair systems on shear bond strength (SBS) of composite to zirconia.

In this in-vitro study, 80 zirconia discs (3mm thickness,6 mm diameter) were randomly divided into four groups included 1) control 2) sandblast with Cojet system 3) Er: YAG 4) and Nd: YAG laser irradiation. Samples in each group were treated with two repair systems (Bisco & Clearfil). The composite was placed on zirconia discs and cured. After thermocycling, SBS was determined by a universal testing machine. The data were analyzed with two-way ANOVA and Tukey HSD (α=0.05).

Mean SBS values ranged from 4/52± 1/26 to 13/79± 3/56 Mpa. The effect of surface treatment on the SBS was significant (p<0.001) but the difference of SBS values based on the repair system was not significant (p=0.56).

Zirconia Sandblast with Cojet system increased SBS to composite. Treatment with two lasers failed to affect bond strength values. Two porcelain repair systems (Clearfil & Bisco) had a similar effect on the bond strength.

The residual periapical cysts are the most common type of odontogenic cysts associated with dysplastic transformations. Therefore, considering the importance of the malignant potential of these transformations, the present study aimed to determine the extent of the dysplastic transformation of residual periapical cysts.

In the present cross-sectional descriptive-analytical study, all the medical records of patients with a distinct diagnosis of residual periapical cyst over a period of 30 years (1989-2018) were extracted from the archives of the Department of Oral and Maxillofacial Pathology of Dentistry School of Isfahan University of Medical Sciences. Following that, the hematoxylin–eosin-stained slide which contained residual periapical lesions were simultaneously examined by two oral and maxillofacial pathologists for the extent of dysplastic transformations with a light microscope. The obtained results were analyzed in SPSS software (version 22) using descriptive, Chi-square, Fisher exact, and t-student tests (α=0.05).

The slides of 197 patients were extracted from the archive which of them, slides of 19 patients were excluded due to distortion, and finally, the slides of 178 patients were analyzed. The dysplastic changes observed were mild in 16 cases and moderate in 1 case. The frequency distribution of dysplasia was not significant based on age, gender, and anatomical location.

In the present study, the prevalence of dysplasia in residual periapical cysts was low (about 10%); nonetheless, due to the malignant potential of dysplastic transformations, further research is recommended.

The present study aimed to evaluate the use of Moodle Mobile educational software designed for iOS and Android operating systems by students for the course of oral and maxillofacial diseases and their satisfaction. 

This educational software was designed to display teachers' information and ways to communicate with them, in addition to displaying various educational data and conducting tests. A total of 46 students who had chosen the course were divided into two groups with Android and iOS operating systems. Finally, the usage rate of students and also their satisfaction with this software were evaluated by gender using a checklist. 

According to the results of this study the most used operating system was Android with a minimum and the maximum number of visits every 120 and 3 minutes, respectively. Girls used the phone almost 1.5 times (more than two hours a day) more than boys. The most use (80%) was only for social networks. The most educational use of the specialized field was half an hour. The average use of this software is about 80 minutes for girls and about 62 minutes for boys. Students' attention to display educational data was increased in the presence of the patient. The conditions for attending the department were mostly related to the display of educational data. Of the 34% who criticized the software, 50% were dissatisfied with the lack of slides. 

The software was well received by the dental students.

The most important cause of failed root canal treatment is poor preparation and obturation of canals, as well as untreated canals. Therefore, understanding the anatomy of the root canal system is the key to the success of root canal treatment. The present study aimed to investigate the morphology of the root canal system of maxillary second molars with fused roots.

In this in vitro study, 50 maxillary second molars with fused roots were mounted, and Cone-beam computed tomography (CBCT) images were obtained. The samples were evaluated for mesiobuccal root canal system based on Vertucci classification, presence of second and third mesiobuccal canals, presence of isthmus between canals, C-shaped anatomy, root connection status, and minimum dentin thickness in the middle third. The data were analyzed using Kruskal-Wallis, Mann-Whitney, and Fisher's exact tests, and a p-value of 0.05 was considered statistically significant.

The most common anatomy was type 1 (42%), followed by types 4 and 6 (16%) and type 2 (14%). The second mesiobuccal and third mesiobuccal canals were observed in 58% and 4% of cases. Isthmus was observed between 11(22%) canals. Moreover, 3 (6%) teeth had C-shaped anatomy. The most common root connection was related to palatal and distobuccal root connection (42%), followed by the connection of all three roots (18%). The minimum dentin thickness in the middle third of the root was obtained at 0.64 mm.

As evidenced by the results of the present study, maxillary second molars with fused roots have a complex root canal system. Furthermore, there was no relationship between root connection and the presence or absence of the second mesiobuccal canal.

Dentistry has many traumatic factors, such as poor workplace posture. These factors result in a high prevalence of musculoskeletal disorders (MSDs) among dentists. This study aimed to evaluate the prevalence of MSDs and its associated risk factors among general dentists in Sari. 

A total of 90 dentists were assessed by the standardized Nordic questionnaire. Data were analyzed by SPSS software (version 24), Chi-square test, and multivariate regression models. A ρ-value <0.05 was statistically significant. 

Among all participants, 64.4% were male, 35.6% were female and 75.6% had MSDs. The most common areas of discomfort were neck (43.3%), shoulders (40.0%), upper back (24.4%), lower back (22.2%), and the wrist (17.7%). In addition, 38.8% and 12.2% had moderate and severe pain, respectively. No statistically significant relationship was found between any of the studied risk factors for MSD (p-value> 0.05).

In the present study, neck and shoulder pain were highly prevalent among dentists. It seems that improving posture at the workplace and the role of physiotherapists in providing precise ergonomic guidelines as well as a punctual performance by dentists to maintain health and well-being is crucial.

The present study aimed to explore the correlation of depression, anxiety, and stress with indices of dental caries and periodontal disease among 15-year-old adolescents living in Bandar Abbas during the academic year 2017-18.

The present descriptive-analytical research was conducted on all 15-year-old students (n=478) in Bandar Abbas. Two individuals were employed for examination in collecting clinical data. Depression, Anxiety, and Stress Scale (DASS21) were completed by students. Then, data were analyzed using descriptive statistics along with ANOVA and Chi-squared test.

Of all the participants in this study, 52.8% of students were male and 47.2% were female. Furthermore, 91.3% of participants' fathers were employed. Also, 33.4% of fathers and 34.3% of mothers had an academic degree. The results indicated a statistically significant difference between anxiety, stress, and depression and simplified oral hygiene index. The majority of students were psychologically classified as average, which was also statistically significant (p<.001).

The present study concluded that the parameters in DASS21 are correlated with oral hygiene indices (periodontitis and dental caries). Therefore, students with better psychological health have higher oral hygiene.

Since first molars are among the first lost teeth, is it common to restore them with dental implants. Considering the amount of remaining mesiodistal space, a wide/medium-diameter implant or two medium/narrow-diameter implants are used in this region. However, the impression procedure can be complicated when two closely adjacent implants are placed.

A patient with two narrow-diameter implants placed in the mandibular right first molar referring for prosthetic restoration. It was not possible to secure both impression copings simultaneously for conventional impression making due to the proximity of implants and the width of impression copings. Therefore, it was decided to follow the altered cast procedure after making two implant impressions, preparing casts, and selecting abutments separately. The preparation of the index for the final cast is possible via using two methods of splinting the final abutments or resin copings intraorally. 

In case that the position of the implants is not ideal, the selection of the proper impression technique is important for achieving a successful prosthetic outcome. The use of the altered cast impression technique in the presence of two adjacent implants in the molar area is helpful for a successful treatment.