Journal of Dental School
Year:2000 | Volume:18 | Issue:2|Papers Count:12

An exact registration of the jaw's relationship is needed to achieve a durable removable denture. Arbitrary Hinge axis point is an example which is recorded by arbitrary facebow. However, the value of this point has yet to be proved in Iranian people. It is, there fore, decided to examine the applicability of a modified beyron's arbitrary Hing Axis to overcome this problem. In this regard, 30 dental students were examied in their true Hinge axis while modified byron technique was employed to assess the differences. Results showed that 86.6% of the readings from Modified byron's were within 5 mm distance from true hinge axis.

Conventional cephalometric radiographs rely on anatomic landmarks and intercranial refrences which automatically results in improper treatment.The aim of this investigation was to evaluate the clinical applicability as well as reliability of the NHP technique.This discriptive research was conducted through a direct evaluation of the radiographs. Cephalometric radiographs were prepared using the NHP method. In this technique a metal chain is placed in front of the face at midline. Fourty five Iranian males and fourty eight females (aged 9 to 14 and 18 to 30 years) were selected all of which had desirable face and normal occlusion. None of these cases had any history of orthognatic surgery while being born normal in vertical and transversal directions.Results were introduced and implemented as the norm for Iranian population.In conclusion: The NHP method has a high degree of reproducibility which therefore could be used by clinicians with minimum error in assessment as shown in this study.

To assess biocompatibility of any materials, animal studies are proved to be reliable. This investigation was designed to evaluate three conventinal root canal sealers (Dorifill, AB26, and Tubliseal) using subcutaneous implantation of the materials.A total of 19 mature Albinus Rats (mean weight 200 ± 25 gr) were selected in which four isolated regions were incised to implant one tube of root canal sealer in 3 regions while an empty tube was implanted in last one.Animals were sacrificed in 7, 14 and 35 days time.After histopathologic preparation, using H & E staining, vascularity and necrosis were evaluated with the thickness of the capsule, intensity, type and extension of inflammation.Results using histopathologic analysis showed that, after 14 and 35 days the thickness of capsule in Tubliseal, was higher than that of the two other sealers. However Dorifill showed a higher intesity of inflammation and necrosis compared to the two other sealers.

In this investigation the amount of fluoride release has been measured from three light activated glass ionomers, a conventional glass ionomer, a compomer and a composite restoration over a period of 12 months. Five discs (7 x 2 mm) of each material were made which were then immersed sequentially in 4 ml of deionised water at 37°C. Samples were rinsed with 1ml of deionised water before each measurement. An orion Model 901 microprocessor digital Ionalyzer was used for the measurements and the obtained data were then converted into µg/cm2. The amount of fluoride release was measured 86 times during this 12 - month test period.Results showed that the pattern of fluoride release from the light activated glass ionomer being similar to that of the conventional glass ionomer restoration. The light activated glass ionomer, however, released significantly more fluoride than the conventional material, while composite and compomer restorations showed the release of significantly lesser amount of fluoride. The difference between flouride release level in composite and compomer restorations was not significant.In conclusion: light cured glass ionomer restorative materials show a higher level of fluoride compared to the conventional glass ionomer, compomer and composite restorations.

The aims of this study was to determine the incidence, etiology and Patterns of midface fracture. A total of 243 hospitalized patients (197 males and 46 females) were evaluated for their traumatic injuries throughout a period of 10 years (1989 - 1999).The prevalence of different traumatic injuries to the midface were measured associated with the most usuall etiologic factors involved. Results indicated that motor vehicle accident (65%) was the most frequent factor. About 30% of all facial fractures was found to be the midface fractures, which could be because of the high incidence of car accident and dashboard (Viplash) injuryies in this country. The mean age of the patients was 29 years. From these 243 patients 81% was male with only 19% females, (males being 5 times more involved). From the midface fractures, zygomatico maxillary complex was the most to be involved.

The incidence of deformities is differing from one population to another. Nevertheless, the rates reported are considerably high. Correction of deformities usually takes place by means of orthognatic surgery, orthodontic treatment or a combination of these procedures. The aim of this research was to assess the prevalence of complications following orthognatic surgical procedures in patients who had undergone this procedure.Patients were selected from those referred to Taleghani Hospital during 1993 to 1997. An existing data analysis was performed by looking up the patients case notes. Results indicated that: from the total of 101 patients, 16.9 percent were suffering from nerve injury with 4.9 percent suffering from bone segment fracture.

Gingival recession is one of the most common problems involving periodontal tissues. Surgical procedures are being introduced for management of this condition.In this study the successfulness of transpositional flap (TPF) is compared to that of laterally positioned flap (LPF). Twenty individual cases with recession at the buccal surface were treated using one of the two mentioned techniques. Evaluation was carried out by means of measuring the amount of root coverage and possible gingival recession in donor site.Results indicated that there was no significant difference between the two groups although the success rate in TPF was slightly higher.

Lichen planus is a common chronic mucocutaneous disease. It's association with lichen planus and diabetes mellius was first reported by Grinspan et al, (1964). The prevalence of histologically approved oral lichen planus has been assessed in the present study. A group of 101 individuals (test group) who were suffering from diabetes mellitus (type I and II) were selected with control group consists of 103 (age - and sex-matched) non-diabetic cases. The mean age of the diabetic group was 46.3 years. Diabetes mellitus was more common in females than males (64.6% vs 35.6%). The prevalence of oral lichen planus was 4.95% and 1.94% in the test and control groups, respectively. However there was no significant difference between the two groups in this respect (P>0.05).

Post design is one of the most important factors on stress distribution. Results of stress analysis would therepore be usefull in selection of different post designs. This study, by using the finite element method, was carried out to assess the distribution of stress in endodontically treated maxillary canine with three different types of post designs.Results showed that maximum stress to be at coronal third of the roots in all models. Minimum tensils and shear stress being recorded in parallel sided posts, while shear stress was recorded at middle third of all models.In addition, minimum stress intensity was observed within tapered post in comparison to all orther designs.

Several full porcelain systems are available in the market, among which In - Ceram (Vita Zahnfabrik, Bad Sackingen, Germany), has been introduced to show unique properties including: fine esthetic and high quality strength. In this investigation Flexural Strength of In - Ceram core material has been evaluated by four - point bending test with Instron (Model 1195) machine. Samples were provided in form of ten bars of core material with the dimension of 30 × 6 × 2.5 mm.Results obtained show that the mean value of 538 ± 42 (MPa), of force is required to hit its resistance limit which is higher than similar values in other dental ceramics, within acceptable clinical range.

Beckwith - Wiedemann Syndrome or partial trisomy of short arm of chromosome 11 is a rare syndrome which patients with this condition represent clinical sings such as: Macroglassia, Viscromegaly, Cardiomegaly and Wilm's tumor. This syndrome involves 1 in 13700 of all infants. Patients are usually referred to Oral and Maxillofacial Surgeons for their true macroglossia. This article represents two individual cases of B.W.S in a family.