Journal of Dentomaxillofacil Radiology, Pathology and Surgery
Volume:9 Issue: 4, Winter 2020

The objective of this study was to compare the Von-Mises-stress (VMS) distribution applied to the edentulous ridges from a Polyamide RPD (PRPD) with those from a Cobalt-Chrome RPD (CCRPD).

A patient with mandibular Kennedy Class I, Mod I was selected. The patientchr(chr('39')39chr('39'))s CBCT was cut off at 1 mm sections from the axial dimension. DICOM files were created. A three-dimensional-bone-model was prepared by segmenting the DICOM files and loading them in MIMICS software and the necessary modifications were applied on them using Geomagic software.The three-dimensional-designs were first developed using Exocad2016 CAD software. An extensive force equivalent to 150N was applied. Abaqus Software was used in order to meshing.  Then the stresses applied on the left and right sides of the edentulous ridges were measured.

In both models, the highest distribution of VMS in the edentulous ridges was observed exactly distal to the abutment teeth adjunct to the distal-extension-areas. In CCRPD, the mean stress on the left-edentulous-ridge was 220kPa and on the right-edentulous-ridge was 100kPa. In PARPD, the mean stress on the left-side-edentulous-ridge was 950kPa and on the right-side-edentulous-ridge was 600kPa. The amount of stresses on the edentulous ridges in the PARPD model (form 280Pa to 950PA) were too much less than those of CCRPD model (from 50kPa to 220kPa).

The polyamide bases can be flexed due to the applied forces and the forces can be distributed in them. So that PRPD can transfer very slight stresses to the underneath surfaces compared to CCRPD.

Aggressive periodontitis is a type of periodontal disease that affects systemically healthy individuals usually under the age of 30 years. It is characterized by rapid bone destruction, which is not proportionate to the quantity of bacterial plaque. The purpose of the present study was to determine the frequency of aggressive periodontitis in periodontics clinic of Rasht dental school in one year period.

In this cross-sectional study, 412 patients were selected among those presenting to the Periodontics clinic of Rasht Dental School during 2016-2017 by convenience sampling. The probing pocket depth (PPD) at 6 areas around the incisors and first molars was recorded for each patient. Those with PPD ≥ 4 mm in more than one tooth were referred for radiographic examination. After extraction of relevant clinical trial parameters, data were analyzed by a descriptive statistical method using IVM SPSS Statistical Software (Version 25).

Of examined patients, only 2 fulfilled the diagnostic criteria for localized aggressive periodontitis. No one was diagnosed with generalized aggressive periodontitis. The frequency of aggressive periodontitis among the patients was %0.48.

The current results were different from those of previous studies on the same age groups with similar diagnostic criteria conducted in other countries. This difference can be attributed to the difference in sample size and different epidemiological patterns of the disease in our target city, Rasht.

The clinical porcelain repair system is almost entirely dependent on the integrity of the bond between porcelain and composite resins.   The preferred manner of conditioning the fitting surface of the ceramic restoration is by etching with hydrofluoric acid followed by the application of a silane coupling agent and bonding resin to achieve a high bond strength. Hydrofluoric acid etching of silica-based ceramics produces insoluble silica-fluoride salts, which can interfere with the bond strength to the resins.

The aim of this study is to evaluate shear bond strength of composite resin to porcelain treated with phosphoric acid compared to ultrasonic cleaner and air-water spray following hydrofluoric acid etching.

66 porcelain disks (Super Porcelain EX3, Noritake) of 8 mm diameter and 3 mm thickness were fabricated and stored in distilled water for 10 days. Porcelain surfaces were abraded with number 023 football shaped bur, etched with 9.5% Hydrofluoric acid and rinsed with water.  The disks were randomly divided into 3 groups: Group 1:  without any additional treatment    Group 2: Etching with 35% phosphoric acid for 30 seconds followed by water spray rinse.    Group 3: Ultrasonic cleaning in distilled water for 5 minutes.Silane and porcelain bonding resin (Bisco Inc.) was applied on the bonding surface of porcelain disks, according to manufacturerchr('39')s instructions. The composite samples (AELITE All Purpose Body) of 4 mm diameter and 3 mm thickness were bonded to the porcelain disks following fixation of a plastic mold on the center of disks.Study samples were stored in distilled water in room temperature for 1 week. Shear bond strength of each specimen was determined using universal testing machine following thermocycling protocol. (1000 cycles between 5°C and 55°C) The fracture modes (adhesive, cohesive, mixed) were examined under scanning electron microscopy at ×25 magnification. Data were analyzed by one-way ANOVA, post hoc Tukey’s test and post-hoc Dunnettchr('39')s t-test.

For both group 2 (P=0.015) and 3 (P<0.0001) the mean bond strength were significantly different from group 1. The bond strength values were significantly higher in group3 compared with group 2. (P=0.011) The highest and lowest bond strength was achieved in group 3 and 1, respectively.

According to increased bond strength between composite resin and ceramic following application of phosphoric acid and ultrasonic cleaning, they are both effective methods for post etching ceramic treatment, whereas regarding to the highest shear bond strength in group 3, ultrasonic cleaning is more recommended than phosphoric acid application.

pulpal exposures originated from the external cervical root resorptions have major effects, on the treatment and prognosis, that could result in tooth loss. This study was performed to compare two different imaging systems-digital periapical radiography with PSP Sensor in three horizontal different views and CBCT images- to assess pulpal exposure in simulated cavity of external cervical root resorptions.

Method and material:

Eighty maxilla central incisor teeth  with straight roots were included. Teeth were randomly divided to two groups (40 teeth with and 40 without pulpal exposures). Each sample was assessed digital radiography with PSP Sensor (in 3 horizontal angles) and CBCT image system, to detect the presence of pulpal exposures. False Negative and False Positive results in 2 imaging procedures were judged with ratio test.

The results showed in CBCT (P.P.V = 85/7) and (N.P.V = 89/5) and in digital intraoral radiography (P.P.V = 80) and (N.P.V = 80) in proximal defects and in CBCT (P.P.V = 93 / 3) and (N.P.V = 100) and intraoral digital radiography (P.P.V = 77/8) and (N.P.V = 75) in buccal defects. In buccal defects, ratio test showed that there is a significant difference between CBCT and intraoral digital radiography technique (0/03>P) but is not significant in proximal defects (0/4>P), (Significance level was 0/05).

The results showed that despite the higher resolution CBCT images than digital intraoral radiography, there were no significant differences in detection of exposure in proximal surfaces between two imaging systems. The differences in detection of buccal defects was significant, the accuracy of CBCT images in detection of buccal defects was significantly higher than PSP digital radiographies.

Temporomandibular Disorder (TMD) is a painful orofacial disorder that includes pain in the temporomandibular joint area, muscular weakness (especially masticatory muscles), mandibular movement limitation and joint clicks. Etiology of TMD is multifactorial and can be the result of psychological stress, occlusal interferences, inappropriate tooth position, dysfunction of masticatory muscle and adjacent structures, or a combination of all these factors. It is aimed to investigate relationships between anxiety, as a risk factor, and TMD.

This cross-sectional study was conducted in summer and fall of 2017 on 100 law students of Islamic Azad University of Bandar-e- Anzali, Iran. In order to investigate signs, symptoms and severity of TMD, the Fonseca questionnaire and for assessing apparent and hidden anxiety, Spielberger questionnaire were used.

The mean scores of hidden and apparent anxiety were 46.37 and 47.30. According to Fonseca questionnaire, most of the people were mildly disturbed by disorder (43%). There was no significant relationship between apparent anxiety and TMD (p <0.646) and There was a positive and significant relationship between hidden anxiety and TMD (p <0.012). The mean score of severity of temporomandibular disorder was 36.12 and most of the people were mildly disturbed by it (43%). According to the Fonseca questionnaire there was a positive and significant relationship between hidden anxiety and TMD (p <0.012).

People with higher hidden anxiety experienced more TMD problems so itchr('39')s better for most patients with TMJ problems to reduce their mental stress apart from dental treatments, otherwise dental treatment will not be sufficiently effective.

Oral mesenchymal lesions account for a large and diverse range from reactive to tumoral lesions. Many studies have been conducted on the frequency of reactive lesions in different countries, though few studies are available on the frequency of soft tissue neoplasms. The present study aimed to investigate the frequency of these lesions in a major oral pathology center in Iran.

This retrospective study was carried out on the documents of Oral Pathology Department, Shahid Beheshti University of Medical Sciences, Iran. Files with a diagnosis of oral mesenchymal lesions were selected. The lesions were categorized into “reactive” and “neoplastic” groups. Chi-square, Kruskal-Wallis, Fisher exact, and T-test were used for statistical analysis.

During the 11 years, 783 patients had oral mesenchymal lesions (22.24%). From these cases, 82.12 % had reactive lesions and 17.75% showed neoplastic lesions. The majority of cases were in their 6th decade of life and the female to male ratio was 1.49:1. Gingiva was the most common site of involvement (45%). 98.46% of the neoplastic lesions were benign and 1.4% were malignant. The most common reactive lesion was irritation fibroma, epulis fissuratum, and pyogenic granuloma respectively. Giant cell fibroma and lipoma were the most common commonest neoplasm.

This study provides a large set of demographic and histopathological data on reactive and neoplastic lesions of the oral connective tissue lesions and showed higher rate of reactive lesions versus neoplastic lesions and benign mesenchymal lesions versus  sarcomas, approximately 4.6 and 70 times respectively.

Due to the important role of imaging in the diagnosis and treatment plan in orthodontics, CBCT (Cone Beam Computed Tomography) images because of their three-dimensional nature, can minimize the disadvantages of two-dimensional images such as magnification, distortion, or superimposition

In the first part, the distances between the 14 anatomical landmarks on the 5 dried human skulls (reference models) identified by metal spheres were measured by a digital caliper. In the next step, CBCT images were scanned from the same reference models. In the second part, radiographic images were taken from 26 patients enrolled according to inclusion and exclusion criteria in three stages, scanning CBCT images, digital LC (Lateral Cephalometric) images from the same CBCT images, manual tracing of digital LC images. Finally, using the obtained data, the accuracy of measurements performed directly on the reference models with CBCT images as well as the CBCT images, digital LC and traced digital LC images of the patients were evaluated together.

The mean of direct measurements on the reference models was not significantly different from the measured values on CBCT images (ρ-value> 0.05). In other words, the measurement of the CBCT images was the same as the reference models. Also, in most cases, linear measurements between the traced LC image with digital LC images and the CBCT of patients were different (ρ-value > 0.05). Meaning traced LC images and digital LC in 8 cases, CBCT and digital LC in 4 cases and finally traced digital LC and CBCT in 5 cases were different.

The present study showed that the accuracy of CBCT image measurements was similar to the direct measurements obtained from the reference models. Also, the accuracy of linear measurements of CBCT images is higher and more reliable than that of digital LC images as well as traced digital LC images.