مجله تحقیق در علوم دندانپزشکی
سال بیستم شماره 1 (پیاپی 75، بهار 1402)

The aim of this study was to investigate the shear bond strengthof composite to Emax porcelain using different methods of ceramic surface preparation (in vitro).

In this laboratory study, 36 porcelain disks were made and divided into four equal groups. The first group was prepared by sandblasting with 50 micron alumina particles, in the second group received porcelain level of 9.5% HF for 20 seconds. Group three was first sandblasted and then by HF 9.5% and the fourth group was first prepared by HF 9.5% and then by sandblasting and the same silane, bonding and composite were applied to 36 samples. Finally, their shear bond strength test was performed. The mean shear bond strength in MPa was analyzed by ANOVA (a = 0.05) and Tukey test. The fracture pattern of the samples was examined by stereomicroscope

The highest mean shear bond streght of the groups was related to sandblast +etching wigh HF(38.52±6.19 MPa), etching with HF+ sandblast (26.8±3.58 Mpa), etching with HF(23.28±4.03 Mpa), respectively and the least streght was reffered to sandblast (18.87±2.15 Mpa). The shear bond streght of composite to Emax porcelain in sandblast group was lower than sandblast and etching with HF group (p<0.001) and etching with HF and sandblast group (p=0.002). This value was significantly higher in sandblast with HF compare to etching with HF group (p<0.001). The Maximum Failure in all groups was cohesive type.

The highest mean shear bond strength of the groups was related to sandblast + etching with HF etching with HF + sandblasting, etching with HF and sandblasting. The most common type of failure in all groups was Cohesive.

The accuracy of linear measurements in CBCT images is one of the critical parameters in treatment planning. Slice thickness and exposure parameters seem to affect the accuracy of linear measurements. In this study, we investigated the impact of the above factors on the accuracy of linear measurements in CBCT.

For the in vitro experiment, three dry human maxilla and mandibles were selected and the roots of their teeth were used as markers at the points of the anterior, premolars, and molars on both sides and placed in the desired locations. A digital caliper was used to measure its height and width prior to placement as the Gold Standard. For each location, the images were examined in slice thickness with dimensions of 0.5, 1, 2 and 3 mm and a kVp = 84 and a kVp = 90 and the results were then compared with Gold standard. The data were analyzed using the ANOVA test.

The results of this study showed that the effect of slice thickness, kvp, location and type of jaw were not significant for measuring the length of the marker (p>0.05) but about measuring the width of marker, in maxillary anterior and molar area and in mandibular premolar and molar area slice thickness was significant (p <0.05) and the effect of kVp was not significant (p >0.05). Similarly, the effects of slice thickness and kVp were also significant in the maxillary premolar area (p <0.05), whereas in the anterior mandibular area, the effect was not significant (p >0.05).

The accuracy of CBCT in measurement is very high although, for CBCT measurements to be as accurate as possible, it is desirable to use thinner slice thicknesses and higher voltages.

One of the concerns about orthodontic treatment is the external apical root resorption(EARR).Therefore, the aim of this study was to compare the rate of EARR in posterior permanent endodontically treated and vital teeth after orthodontic treatment.

This observational and retrospective study was performed on 112 roots in 28 patients in the age range of 20 to 30 referred to the orthodontic department of Isfahan Azad University who had endodontically traeted teeth on one side of the jaw and contralateral vital teeth on the opposite side. The studied roots were maxillary first and second molars roots (mesiobuccal and distobuccal roots), mandibular first and second molars roots (mesiolingual and mesiobuccal and distal). Two panoramic radiographs were taken before orthodontic treatment and at least one year after orthodontic treatment. In both radiographies, the ratio of crown length to root length was measured in the endodontically treated teeth and the contralateral vital tooth. The results were analyzed using Mann-Whitney test.

There was a significant difference in the external resorption of distal (p = 0.001) and mesial (p <0.001) roots between endodontically treated and contralateral vital teeth, but there was no significant difference between distobuccal and mesiobuccal roots of maxillary posterior permanent vital teeth (p=0.499), endodontically treated teeth (p = 0.249), mesial and distal roots of mandibular posterior permanent vital teeth (p = 0.398), endodontically treated teeth (p = 0.193).There was no significant difference in the external resorption of mesial roots of vital teeth (p. 0.075), mesial (p. 0.243) and distal (p = 0.324)roots of endodontically treated teeth between maxillary and mandibular teeth but a significant difference was observed in the distal roots in the vital teeth. (P = 0.014) and root resorption in the distal roots of the maxilla was more than the mandible.

External apical root resorption after orthodontic treatment in posterior endodontically treated teeth was lower than vital teeth.

Cutaneous squamous cell carcinoma (CSCC) is the second most common skin cancer. Mast cells may play a role in tumor progression and metastasis by increasing angiogenesis. The aim of this study was to investigate the role of mast cells by increasing angiogenesis in invasion of head and neck cutaneous squamous cell carcinoma.

In this cross-sectional study, 4 microns slices gotten from 30 paraffined blocks of head & neck well differentiated CSCC stained for evaluation of small blood vessels density using CD34 immunomarker and evaluation of mast cell density with toluidine blue. The number of small vessels and mast cells were counted in ten microscopic fields in the areas with the highest density. Data were analyzed using SPSS software version 21 and Mann Whitney, Kruskal-wallis and Pearson's correlation coefficient tests. Significance level was considered as P <0.05.

There was no statistically significant relationship between the density of mast cells and the density of small blood vessels and whether the increase in mast cells causes the increase of small blood vessels or not. (P = 0.142) and correlation coefficient (r = 0.274).

According to the results obtained in this study, based on the lack of correlation between the density of small blood vessels and the number of mast cells in cutaneous squamous cell carcinoma, this trend does not seem to play a role in the pathogenesis of head & neck cutaneous squamous cell carcinoma.

Preserving deciduous teeth is necessary to have regular permanent teeth and parents play an important role in this field. In this study, the knowledge, attitude and practice of parents of children aged 6 to 12 years about caring for primary teeth were assessed.

In this descriptive-analytical and cross-sectional study, 148 parents of children aged 6 to 12 years referred to Alborz Dental School in 2020 participated. Their knowledge, attitude and practice were measured using a questionnaire whose validity and reliability were confirmed. Data were analyzed using SPSS software version 22.

: More than 81% of the participants were mothers. Most families had one child and the highest level of education of parents was diploma More than 83% of mothers were housewives, more than 87% of fathers were employed and 84. 5% of parents were married. In parents, the level of knowledge was poor, the level of attitude was good and the level of performance was poor. The level of knowledge had a significant relationship with the employment status of mothers (p=0. 028). Attitude level had a significant relationship with mothers' education (p=0. 023). Performance level had a significant relationship with father's education (p=0. 039), mother's education (p<0. 01), mother's employment status (p= 0. 005) and father's employment status (p=0. 013). Working mothers and fathers had higher performance levels than housewives and unemployed fathers.

It seems necessary to take measures to educate parents about taking care of milk teeth of children aged 6 to 12 years.

Recurrent aphthous stomatitis is one of the most common inflammatory diseases of the oral mucosa with multifactorial etiology . Psychological factors is one of possible factors cause to recurrent aphthous ulcers and salivary cortisol level also influenced by anxiety, this study aimed to compare salivary cortisol levels in patients with recurrent aphthous ulcers( during active disease and after healing )with healthy persons.

In this case-control study unstimulated salivary samples from 30 patient with RAS above 10 years (in active ulcerative stage and 2 days after healing) and 30 healthy subjects (control group) who age and gender were matched was collected and transferred to the laboratory for salivary cortisol levels measurement )Eliza method). Hamilton Anxiety Scale questionnaire was also completed to assess the level of anxiety for participants. Data were analyzed using Spss 20 and sample T-Test

Salivary cortisol levels in patients with RAS in active ulcerative and healing periods no significant different(P=0.171). Salivary cortisol levels in healthy subjects and patients with RAS in acute phase no significant different (p=0.272). Also cortisol levels in patients with recurrent aphthous stomatitis in healing period and control group no significant different .(P = 0.97) The mean anxiety level of people with RAS 17.6 ± 3.2 and healthy people 15.9± 2.7 no significant different (P˃0.05)

Considering to the result ,salivary cortisol levels in ulcerative period and after healing in patients with RAS and healthy subjects no different . Also, anxiety and cortisol levels no related to aphthea occurrence .

Musculoskeletal disorders are global problems and have a significant impact on quality of life. Studies show that the symptoms are shown in dental students before graduation. The purpose of this study was to investigate the prevalence of musculoskeletal disorders in dental students.

This study is a cross-sectional descriptive analytical study. The study population was dental students working in pre-clinics and clinics of Mazandaran University of Medical Sciences. The data collection tool was Nordic standard questionnaire. The collected data were entered in SPSS 22 statistical software and were analyzed.

The data of 121 participants were analyzed. 84 participants (%69.4)had felt pain, discomfort or numbness in at least one part of their body which was mostly in neck (%45.5). No significant relationship was found between right handed/ left handed variables and musculoskeletal disorders (P-Value= 0.862).

The prevalence of musculoskeletal disorders among dental students is high. Prevalence measures and further educations must be provided in dental schools.

The aim of this review study was to evaluate the results and effects of employing or not using bone graft materials in the buccal gap around the immediate implant, on the alveolar bone dimensions and the success of the implant and its complications after immediate implant placement.

This study was conducted using electronic versions of articles in Pupmed and Google Scholar from 2010 to 20/4/2022. The extracted electronic articles include 14 randomized clinical trial studies, a high number case report and two systematic reviews based on clinical trial. All the researches are human clinical studies . Articles written in English and Persian, as well as laboratory and animal studies and the use of collagen membranes during immediate implant placement, have been excluded from the study. The age of patients is over 18 years and the duration of evaluation is four months and more. Finally, 17 articles were reviewed.

The effect of using or not using Bone Graft in buccal gap on implant failure cannot be confirmed. It does not seem to have a significant effect on reducing the horizontal and vertical dimension of the buccal plate and has a moderate effect on the beauty of the soft tissue around the implant and the amount of mid-buccal gingival mucosa dimension and reducing the horizontal and vertical dimension of the buccal plate. With the use of bone powder, minor surgical complications such as pain are slightly increased.

Nowadays, in the treatment of necrotic teeth with open apex, based on the availability of bioceramic biomaterials with the ability of calcified tissue induction on cement and bone and periodontal ligament repairment stimulation using these materials has become more acceptable than the traditional calcium hydroxide apexification method. Cold ceramic is one of these bioceramics that in previous studies has shown successful results in the treatment of apexification.

Case Report:

 This article was a report of a successful case of apexification with cold ceramic and 10-months follow up of second mandibular molar tooth of a 14-year-old girl. In 10-month-old follow up, the tooth was asymptomatic and the periapical lesion healed after 10 months.

: It seems that cold ceramic could be used as a desirable material in the treatment of apexification and to strengthen the regeneration of periapical tissue.