dr. azam sadat madani

This study aimed to evaluate the association between temporomandibular joint (TMJ) structure and occlusal support status using computed tomography (CT) images.

In this cross-sectional study, the computed tomography (CT) scans of 90 patients were categorized into six groups based on the number of posterior and anterior occlusal support areas (Eichner classification). In CT images, the articular eminence inclination, and glenoid fossa depth and angle were measured. Furthermore, condylar shape and position, and the presence of condyle-flattering or other pathologic changes were recorded. The TMJ variables were compared between different Eichner classification groups. The data were analyzed by paired samples T-tests, one-way ANOVA, and chi-square test (α=0.05).

The loss of posterior occlusal support was associated with TMJ flattening and a posterior condylar position (P<0.001). No significant difference was found in the inclination of the articular eminence and depth of the glenoid fossa between different Eichner groups (P>0.05). In patients with unilateral occlusal support, the TMJ on the edentulous side had a significantly lower articular eminence inclination, a greater angle of the glenoid fossa, and a decreased glenoid fossa depth (P<0.001).

Loss of posterior occlusal support may lead to changes in the structure of the glenoid fossa, joint space, and condylar position and cause flattening of the condyle. These changes may predispose the joint to degenerative changes.

The effectiveness of two soft and hard splint thicknesses in reducing temporomandibular joint (TMJ) pain and dysfunction was compared.

Sixty patients with TMJ pain and dysfunction were randomly assigned to four groups (n=15); the patients treated with hard occlusal splints of 1 and 3mm thicknesses were assigned to Groups A and B, respectively, and those treated with soft occlusal splints of 1 and 3mm thicknesses were assigned to Groups C and D, respectively. Maximum mouth opening (MMO) and the severity of pain based on the visual analog scale (VAS) were assessed before treatment and after 7, 30 and 90 days.

After both 7 and 30 days, no significant differences were found between the groups for any variable (P>0.05). However, Group C had a significantly lower MMO compared to Groups A and B after 90 days (P=0.001). Additionally, and in relation to masticatory muscle pain, Group C had a significantly higher VAS score than other groups (P<0.05). The VAS score for TMJ pain at rest was also significantly higher in Group C compared to Groups A and B (P<0.05).

A 3-mm hard occlusal splint seems to be the best treatment to reduce pain and dysfunction of the TMJ.

This study aimed to evaluate the treatment outcomes of patients with temporomandibular disorder (TMD). This cross-sectional study examined records of 165 TMD patients who referred to the Department of Prosthodontics at the Dental School of Mashhad University of Medical Sciences, Iran, from 2012 to 2017. Patients were recalled and clinically reexamined for reduced signs and symptoms or total improvement. Treatment outcomes were characterized as “improved” and “not improved” in terms of clicking sound and pain in the joint. The data were analyzed using SPSS software (version 18) using the Chi-squared and Fisher's exact tests at a significance level of less than 0.05 (P<0.05). The subjects included 53 males (32.1%) and 112 females (67.9%) with a mean ±SD age of 31.7 ± 13.6 years. The patients with a locked mandible and joint sounds while opening their mouth or chewing recovered significantly. Moreover, a significant association was found between improvement and the absence of the anterior slide, and patients without an anterior slide improved better than those with the anterior slide (P<0.05). The use of conservative methods in the treatment of TMD is highly recommended regardless of factors such as age, gender, and clinical symptoms.

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.

Thetemporomandibular joint works in conjunction with other neuromuscular components. Defects in any of these components or factors prevent their coordinated activity and lead to temporomandibular disorders (TMD). The aim of this study was evaluation of relationship between depth of curve of spee and symptoms of temporomandibular disorders in patients referred to Occlusion section of Prosthodontics department of Mashhad Dental School during 2018-2019.

55 patients were studied in Mashhad Dental School. TMD symptoms included pain severity, maximum mouth opening (MMO), and the joint click was examined. Pain severity was assessed using the Visual Analogue Scale. Then, the alginate impression was prepared from the mandible and casts made and trimmed with type IV stone. Finally, a digital ruler used to measure the depth of the curve of Spee in the mandible and the relationship between the symptoms and the depth of curve of Spee measured by independent t-test.

Thirty-eight women (69.1%) and 17 men (30.9%) with a mean age of 28.1 ± 7.2 years and age range of 15 to 52 years were studied. The mean total depth of curve of Spee in females was 2.08 ±0.78 mm and in males was 1.72 ± 0.67 mm, which was not statistically significant (p = 0.86). Also, the mean total depth of curve of Spee in patients with and without TMJ click was 1.82 ± 0.52 mm and 2.09 ± 0.90 mm, respectively which was not statistically significant (p = 0.18).Also, there is no siginificant difference between  MMO and severity of pain with curve of space. (P>0.05)

In this study, although the mean depth of Curve of Spee in the patients with joint click was lower than the patients without joint click, this difference was not statistically significant. There was also no significant relationship between other symptoms of patients with TMD including pain intensity, maximal mouth opening (MMO) and Curve of Spee in the mandible.

Statement of the Problem: Despite yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) high strength in dental restoration application, Zr- the framework has a low tendency to react chemically with cement which is the main reason of these restoration failures. The aim of this in-vitro study was to evaluate the effect of Y-TZP coating by nanocomposite of silica and aluminosilicate according to the sol-gel dip-coating technique on the bond strength of resin cement to Y-TZP.   In this experimental study, Y-TZP blocks (10×10×3  ) were prepared and sintered and assigned into 4 groups (n=10) for coating including control group without any further surface treatment, sandblasted using 110 μm alumina particles under 2.5 bar and tip distance of 10 mm, silica sol dip coating + calcination, aluminosilicate sol dip coating+ calcinations. To confirm chemical bonds of sol-gel covers, Fourier transforms infrared spectroscopy (FT-IR) technique was used. The surface of the sample was investigated by Scanning electron microscopy (SEM), energy-dispersive spectroscopy detector (EDS) and x-ray diffraction (XRD) methods. Micro-shear bond strengths (µSBS) of zirconia-cement specimens were evaluated. Data were analyzed with a one-way ANOVA test in SPSS version 11.5 software with a confidence interval of 95%.  µSBS of sandblasting, nano-silica, and nano-aluminosilicate specimens were significantly higher than control. µSBS of nano-silica was higher than other groups but no significant difference was observed in µSBS of sandblasting nano-silica, and nano-aluminosilicate groups (p Value > 0.05). Covering the zirconia surface with non-invasive nano-silica and nano-aluminosilicate using the sol-gel technique leads to improved cement bond strength.

We describe an interesting case of oral sub mucous fibrosis accompanied by severe trismus in a 23 years old man. The patient had initially been diagnosed as having internal derangement of the temporomandibular joint and conservative treatment had failed to decrease the symptoms. Despite extremely limited temporomandibular joint movement, cone beam computed tomography revealed no important abnormality. The patient had been referred to Mashhad Dental School for further evaluation. On detailed case history, the patient revealed oral adverse habits such as pan & tobacco chewing and on palpation fibrous bands were noticed on the anterior and some parts of buccal mucosa; therefore, the patient was diagnosed with oral submucous fibrosis and underwent surgical excision of fibrous bands.

  The present study aimed to review the condylar changes in the patients with osteoarthritis using cone beam computed tomography (CBCT) images. In this study, 80 CBCT images of the temporomandibular joint (TMJ) pertaining 20 patients with osteoarthritis and 20 healthy individuals were evaluated, as well as the CBCT images that were obtained for other reasons. The images were reviewed in the coronal and sagittal sections. Considering the higher prevalence of osteoarthritis in women and after eliminating gender-based interventions, all the female patients were enrolled in the study. Chi-square was used to evaluate the correlations between the changes in the condylar head by the grouping of the patients, and the significance level was considered at 0.05. The correlation of condylar head flattening (P=0.051) and Ely’s cysts (P=0.544) was assessed in the control group and osteoarthritis patients, and no significant difference was observed between the two variables and patient classification. In addition, the association between erosion (P<0.001) and osteophyte (P=0.002) of the condylar head was evaluated in the control group and osteoarthritis patients, and the presence or absence of these conditions had a significant correlation with disease grouping. According to the results, the presence of osteophyte and erosion was more significant in the osteoarthritis group compared to the healthy subjects. The most prevalent bony changes in the condylar head were due to flattening, and the less prevalent changes were associated with Ely’s cysts. Moreover, osteophyte and erosion were more prevalent in the patients with osteoarthritis.  

  Inappropriate occlusal contacts may have deleterious effects on dentofacial system. Regarding the importance of the effect of trauma from occlusion on pulpal inflammation and periapical destruction, the present study was performed to evaluate the trauma effects on pulp and periapical histologically. This study was conducted on the basis of an experimental design for animal studies. Composite repairs, 1.5 mm in height, were placed on the right mandibular first molars of 16 dogs (2 randomized groups of 8 cases). One group of dogs were perfused after 48 hours and the second group were subjected to perfusion after 30 days. Subsequently, the histologic examination was performed and the data were analyzed using SPSS (version13). The levels of inflammation in coronal and apical pulp, periapical, and periodontal ligament (PDL) after 48 hours were obtained as 25%, 37.5%, 12.5%, and 12.5% and were 37.5%, 50%, 25% and 12.5% in maxillary and mandibular molars, respectively. After 30 days, the levels of inflammation were 75%, 75%, 12.5%, and 12.5% and were 87.5%, 100%, 25%, and 25% in maxillary and mandibular molars, respectively. The levels of pulp and periapical inflammation after 30 days were significantly more than those after 48 hours (P<0.001). The apical pulp obtained more inflammation compared to the coronal one. In addition, the periapical inflammation was more developed than that of PDL (P<0.001). Following the trauma from occlusion on dog’s molar teeth, the levels of pulp and periapical inflammation after 30 days were significantly higher than those after 48 hours.The lower teeth inflammation was more chronic and pronounced; however, there was no significant association between the severity and type of inflammation following the acute and chronic trauma and tooth positions

Temporomandibular disorders (TMD) are defined as clinical conditions that involve the masticatory muscles, temporomandibular joint (TMJ) or both. The aim of this study was to evaluate the relationship between symptoms and recovery in patients with TMD. In this cross-sectional study, 165 records of patients with TMD referring to the Department of Occlusion, Mashhad Dental School from 2012 to 2017 were surveyed. Before the clinical examination, all the patients completed a questionnaire on their personal data and symptoms of joint disorders. All the patients were contacted and data were collected about the decrease in symptoms of joint disorder or its health. The treatment outcomes were characterized by a lack of recovery and improvements in joint symptoms. Data were analyzed with SPSS 18, using chi-squared and Fisher’s exact tests (α = 0.05). The records belonged to 53 men (32.1%) and 112 women (67.9%). The mean age of the subjects was 31.7 ± 13.6 years. The youngest and oldest subjects were 12 and 70 years of age, respectively. The number of women experiencing improvements was higher than men, but the difference was not statistically significant (p value = 0.145). Patients with joint clicks during mastication or mouth opening experienced significant improvements compared to those without these clicks (p value = 0.05). In general, use of conservative methods for the treatment of TMJ disorders is recommended. These therapies can be useful for all the individuals with TMD, regardless of variables such as age, sex, symptoms and habits

The aim of this study was to assess the association between the clinical and cone-beam computed tomography (CBCT) findings in relation to bony changes in patients with temporomandibular disorders (TMD).
According to the research diagnostic criteria for temporomandibular disorder (RDC/TMD), forty-one patients with type II TMD (42 TM joints) and type III TMD (40 TM joints) were recruited for this study. Condylar position and bony changes including flattening, sclerosis, osteophytes, resorption, and erosion of joint were evaluated by CBCT and compared with clinical findings. Data were analyzed by SPSS software.
Condylar flattening, sclerosis, resorption, and erosion were not significantly associated with joint/masticatory muscles pain or crepitus sound. The vertical or horizontal position of the condyle showed no significant relationship with the clinical findings. Condylar osteophyte was significantly associated with pain in masticatory muscles and crepitus (P = 0.030 and P = 0.010, respectively). There was no association between the condylar range of motion and pain in joint or masticatory muscles.
Condylar osteophyte was significantly associated with both masticatory muscles pain and crepitus sound. No significant relationship was found between the other temporomandibular joint (TMJ) radiographic and clinical findings in patients with TMD.

Serum levels of micronutrients change when most inflammations and infections occur. We aimed to evaluate serum levels of selenium (Se), magnesium (Mg), sodium (Na), zinc (Zn), and copper (Cu) in patients with temporomandibular joint disorders and compare them with healthy control group.
In this case-control study, 60 participants were selected from among patients who were referred to School of Dentistry of Mashhad University of Medical Sciences, Mashhad, Iran, due to temporomandibular joint disorders. All the participants were examined by a prosthodontist, who was expert in occlusion. Twenty patients with muscular disorder, 20 patients with articular disorder (disc dislocation with reduction), 20 patients with inflammatory disorder, as well as 20 healthy controls were chosen. Se, Mg, Na, Zn, and Cu levels were assessed using flame atomic absorption spectrometry in all the participants. To analyse the data, Kruskal–Wallis, Chi-squared, and Fisher’s Exact tests were run (P Mean age of the participants was 31.7±9.31 years. Overall, 25 (31.6%) cases were male and 54 (68.4%) were female. Serum levels of zinc, magnesium, sodium, copper, and selenium in the patients with muscular disorder were 67.68, 1.94, 140.05, 122.74, and 122.08, while these values were 65, 1.94, 138.95, 116.94, and 110.79 in the patients with articular disorder, 65.65, 1.84, 136.32, 120.96, and 105.75 in the patients with inflammatory disorder, and 62.4, 1.8, 135.4, 138.51 and 110.58 in the control group, respectively.
The mean serum level of sodium in the muscular group was significantly higher in comparison with those in the osteoarthritis and control groups. Furthermore, this value was significantly higher in the articular disorder (disc dislocation with reduction)group than the control group.

The present study aims at studying graduate and postgraduate students and faculty members’ points of view of Dental School of Mashhad University of Medical Sciences regarding the quality of library services through Libqual instrument. This is a survey study with research population of 148 graduate and postgraduate research students and faculty members of Mashhad Dental School. Study instrument is Libqual-based questionnaire modified according to the status of Dental School’s library. Participants answered the items in two levels of “Available & Expected”. There was a significant difference among three groups regarding two components of service quality and information control. However, this difference was not significant regarding library space component. In Expected status, there was no difference in three components among three groups. The scores of all study components were significantly lower than ideal in both available and expected status. Given the study limitation, presented aspects of Libqual and according to the library users’ opinions, the study components were not optimal indicating the necessity of more considerations toward improving library services quality.
Keywords: Service quality evaluation, Libqual model, university library, Mashhad Dental School

Attention deficit / hyperactivity disorder, is a common psychological disorder in persons, that continues from childhood into adulthood and leads to problem in various aspects of their life, such as personal, social, professional, and executive function such as working memory. Several studies indicate a close relationship between working memory deficits and attention deficit / hyperactivity disorder. Given the lack of studies on the effectiveness of neurofeedback in improving working memory in adults with ADHD, this study was designed to evaluate the effectiveness of neurofeedback in working memory.
Research design was experimental with pre-test and post-test and control group and carried out on adults with attention deficit / hyperactivity disorder referred to the Atieh clinic in Tehran .After reviewing inclusion and exclusion criteria,16 persons based on purposive sampling were selected in 2 groups of 8 cases as experimental and control groups. The research instruments were the Beck Anxiety Inventory, Beck Depression Inventory, Inventory adult attention deficit/ hyperactivity disorder of Barkley, vital cns test, auditory and visual integrated test signs. Data analysis, through SPSS software using U Mann-Whitney, was performed. The independent t-test, Wilcoxon and Kruskal-Wallis tests were used also for complementary results. The protocol used in this study, was increasing of beta waves on FZ.
The results showed that neurofeedback was led to a significant increase in working memory in experimental group.
According to the results of this study, which is consistent with results of the researches done in this field, neurofeedback increases frontal lobe activity and activation of neural circuits involved in executive function and working memory, and improve executive function and working memory deficits in patients with attention deficit / hyperactivity disorder. As a result, given the efficacy of neurofeedback in improving working memory, using this method, is suggested for the same treatment.

In this study silica-coated alumina particles (Cojet sand) were irradiated by CO2 laser and Nd:YAG laser with the intention of stabilization on the metal surface and bond strength to composite resin was evaluated.
Forty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 µm aluminum oxide particles. Specimens were divided into four groups that received the following surface treatments: 1-airborne-particle abrasion alone (A.A); 2- airborne-particle abrasion with Cojet sand; 3-metal surface coated with Cojet sand and irradiated by Nd:YAG laser (CJ-Lased-Nd:YAG); 4- metal surface coated with Cojet sand and irradiated by CO2 laser (CJ-Lased-CO2). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy. The shear bond strength values were analyzed using ANOVA and Tukey’s tests (α=0.05).
Si-CO showed significantly higher shear bond strength in comparison to other groups (P0.05). In Si-CO group, the failure mode was mostly cohesive; but other groups showed adhesive failure in the metal-composite interface.
Silica-lasing with Cojet sand and irradiation of Nd:YAG or CO2 laser is not an effective method in improving metal-composite bond strength.

The aim of this study was to investigate whether there is any relationship between the condition of complete dentures and TMDs. The sample consisted of 61 consecutive patients (35 females and 26 males) who were admitted to the Department of Prosthodontics of Mashhad Faculty of Dentistry for fabrication of new complete dentures. The age range of the participants was between 32 and 80 years, with the mean age of 57.05±10.26 years. The patients were examined by two prosthodontists. Using a questionnaire, the first prosthodontist asked the patients about their habits and history of trauma to the temporomandibular joints (TMJs). She then examined the participants for signs and symptoms of temporomandibular disorders (TMDs). The second prosthodontist examined each participant''s existing denture and checked its fit, stability, retention, occlusion, and centric relation, and recorded how long it had been in service. The examination was double blind. The data were recorded in examination sheets. The relationship between TMDs and denture fit, stability, retention, centric relation and occlusion was analyzed using Fisher’s Exact Test. No significant relationship was found between denture characteristics and TMDs in complete denture wearers (P-value>0.05). Complete denture characteristics did not play a role in the development of TMDs in edentulous patients.

Temporomandibular joint disorders (TMD) are the most common disorders of the jaw, and despite their clinical importance, they are not completely understood. This study was aimed to evaluate the changes of temporomandibular joint (TMJ) on cone beam computed tomography (CBCT) images in disc displacement vs. osteoarthritis of the TMJ. In this study, 45 patients, including 37 women and 8 men (13-89 years of age), were examined. The patients were selected based on RDC/TMD criteria and group I disorders were excluded from the study. Accordingly, group II consisted of 43 joints with jaw clicking or displaced discs, and group III comprised 46 joints with crepitus. CBCT images in sagittal, coronal, and axial sections were examined to assess osseous changes in terms of flattening, sclerosis, erosion, resorption, and osteophyte formation. Data were analyzed using statistical tests including the chi-square, Mann-Whitney, and Kolmogorov-Smirnov tests with the confidence interval of 95%. Mann-Whitney test for the comparison of mean age between groups II and III was not statistically significant (p value=0.06). A significant differences was found between two (RDC/TMD) groups according to the prevalence of condylar erosion, resorption, and osteophyte (p<0.05). Similar findings were present between articular eminence flattening, erosion, resorption and (RDC/TMD) groups (P-value<0.05). The pattern of bony changes was different in osteoarthritis when compared with in disc displacement. Most of the changes were concentrated in various parts of the condyle and the articular eminence with no particular changes in the mandibular fossa

Internal derangements of temporomandibular joint are the most common type of joint disorders after muscle disorders and include all disorders related to incompatibility and dislocation of disc and condyle. The purpose of this study was to evaluate disc position in patients with temporomandibular joint (TMJ) clicking referring to occlusion unit of Mashhad dental school using magnetic resonance imaging (MRI) as the gold standard. Sixty-eight joints in 34 patients diagnosed with TMJ clicking were studied using MRI. Sagital MR images were obtained with 0. 5 Tesla magnetic resonance system in the open and closed mouth position to evaluate disc position in relation to the fossa. The data were analyzed using Chi-square and Fisher’s Exact tests. Disc displacements (DDs) were observed in 54. 4% of the TMJs analysed. Joints with intermediate and late clicking showed more DDs. Anterior DDs were observed in 41. 2% of the joints. The amount of DD in joints with clicking sound was significantly higher than that of those without clicking. We found that the presence of clicking sound in the clinical examination could not always predict DD. Thus، MRI presents as the gold standard for the detection of DD.

It has been shown that joint click, an initial and common finding in internal derangement (ID), respond to neither conservative treatment nor surgical intervention. This raises the question as to whether it must be treated in the absence of other pertinent signs and symptoms, so the aim of this study was to investigate and compare the MRI findings of TMJ in both normal subjects and patients with click, in order to determine the importance of click in predicting TMJ pathological changes. A total of 26 patients with clinical symptoms of disk displacement with reduction (DDwR) according to RDC/TMD were compared to 14 normal subjects in terms of their MRI findings, including disk displacement, effusion, condylar osteoarthritic changes and disk deformities. Out of 80 joints in total (52 affected joints in 26 patients and 28 joints in control group), 48 were shown with normal disk position in MRI whereas 28 (35%) and 4 (5%) were categorised as DDwR and (disk displacement without reduction) DDwoR, respectively. Statistically significant correlations were established between the following pairs of variables in order: Click and disk displacement, effusion and disk displacement, disk displacement and effusion with disk deformity. The correlation between the presence of click and disk displacement, disk deformity and effusion emphasizes the importance of MRI for an accurate diagnosis and development of an appropriate treatment plan in these cases and shows that clinical examination is not sufficient for these purposes.

Full crown preparation may have adverse effects on pulp tissue. In this study, the effect of full-crown preparation on intact versus inflamed pulp tissue was studied. Fifteen healthy mature cats were randomly selected for this study. The study was performed on four canine teeth of each cat. Cats were anesthetized and then radiographs were taken from the canine teeth. Class V cavities were prepared in cat canine teeth. Soft decayed dentin was placed on the floor of cavities and sealed. After 1 month, all of the samples prepared for crown fabrication. Before crown preparation, an impression was taken in a custom tray. During crown preparation, the remnants of carious dentin were removed and undercuts were sealed by glass-ionomer. After preparation, self-cured acrylic temporary crowns were fabricated in a direct procedure and cemented permanently by glass-ionomer. One week later, teeth of the opposite jaw were prepared in a similar procedure. After 2 months, vital perfusion performed and the pulp tissue was histologically examined. There was no significant difference between 4 groups, regarding to histologic status of the pulp. In healthy lower jaw, inflammation was the most frequent but in the other groups, necrosis was most frequent. Also, there was no significant difference between the upper jaw and the lower jaw groups regarding to the frequency of necrosis and inflammation. There is no significant difference between intact and inflamed groups regarding the frequency of necrosis and inflammation

The aim of this study was to evaluate the effect of bridge orientation in casting machine on castability and quality of base metal castings. Three groups of patterns with different direction and lengths in casting machine were casted and then studied qualitatively and quantitatively using mean and standard deviation in table of frequency. Larger nodules and porosities were on the joints of sprue in horizontal specimens (P=0.01 and 0.048, respectively). There was no significant difference in castability between 3-, 5- and 6-unit bridges in relation to their direction in casting machine (P=0.5). An increase in bridge length led to more variation in length and width. The position of bridges also played an important role in the length variation in bridges. The direction of bridges had no effect on base metal castability but a vertical position resulted in a better casting quality and an increase in length of the bridges caused more defects in castings.

Angle and internal position of lateral pterygoid muscle leads to contraction over two half of the mandible in maximum opening and protrusion position so it can affects impression prosthetic procedures. The aim of this study was to evaluate the mandibular flexure in two transverse and antro-posterior dimensions. Seventy edentulous patients at Mashhad Faculty of Dentistry as the main group and 50 dentulous patients as the control group were selected. In these patients, transverse dimensions between second molar areas and also canine eminence from one side to another side, and longitudinal dimensions based on the distance between canine to second molar area at centric occlusion and maximum mouth opening were measured. Dimensional differences as the mandibular flexure were measured. The mandibular dimensions in maximum opening and closed mouth were different. Average reduction in transverse dimension on second molar region at maximum mouth opening and closing position were almost equal to -0.0787 mm for target group and 0.7512 mm for control group. On anterior side, averages of these changes were equal to 0.3069 mm for target group and were 0.2254 mm for control group. Transverse dimensions in anterior region at maximum opening position are smaller than the same dimension at closed mouth in edentulous and dentulous patients.

Some factors can affect T.M.J. In this survey, prevalence of etiologic factors such as trauma, dental premature contacts, parafunctional habits and psychologic factors was studied. Methods & Materials: 100 patients who had T.M.D and referred to Mashhad Dental School was examined. For each patient a questionnaire was provided and etiologic factors evaluated. The most of patients were affected by pscychologic factors (77%). The next lateral eccentric premature contacts were higher than others (71%). Followed by clenching (38%), Bruxism (21%) and Trauma to T.M.J or chin (19%). The most important etiologic factor of TMD was psychologic followed by lateral eccentric premature contacts.