مجله دانشکده دندان پزشکی اصفهان
سال نهم شماره 4 (پیاپی 39، مهر 1392)

The primary goal in treatment of edentulous patients is satisfaction enhancement. Excessive pressure on denture-supporting tissues results in patient discomfort. Different occlusal schemes are used in the fabrication of complete dentures. In this study after introducing the new buccalized occlusion، pressure level under the denture base is compared between full bilaterally balanced and lingualized occlusions during chewing. In this experimental study، three sets of complete dentures were fabricated with different occlusal patterns under simulated in vitro conditions for 5 patients. Then، transmitted stress level from denture base to artificial tissue at the buccal shelf was measured using strain gauge during crushing of carrot cubes and carrot sheets. The mean pressure values were compared with paired-t test using SPSS 16 at p value ≤ 0. 05. The transmitted pressure was significantly higher with full bilaterally balanced occlusion compared to lingualized (p value = 0. 03) and buccalized (p value = 0. 04) occlusion patterns during crushing the carrot sheets. In crushing the carrot cubes، there was no significant differences (p value = 0. 24 and p value = 0. 45). Furthermore، no significant differences were found between lingualized and buccalized occlusion patterns during crushing of carrot sheets (p value = 0. 74). Under the limitations of the present study، lingualized occlusion and buccalized occlusion transmit less pressure to buccal shelves in crushing the carrot sheets.

At present different techniques are used for the removal of carious lesions. Chemomechanical caries removal technique is a noninvasive technique that removes the infected tissue، and at the same time، maintains sound tooth structures and prevents pulpal irritation and patient discomfort. The aim of this study was to evaluate shear bond strength of a two-step self-etch adhesive to demineralized dentin after caries removal in primary molars with Carisolv in comparison with a handpiece.

In this in vitro study، 60 freshly extracted primary molars with occlusal caries were collected. The samples were divided into two groups. In each group، the teeth were cut in mesiodistal and buccolingual directions to prepare four samples. In group 1، the carious lesions were removed using Carisolv gel and in group 2، they were removed using a bur in a handpiece. Then the teeth were restored with composite resin and Clearfill SE Bond adhesive، using molds measuring 2 mm in height and 1. 4 mm in diameter. The bonding interface underwent a shear strength test in a universal testing machine. Numerical values ​​of shear bond strength (SBS) were calculated for each group، and statistical analysis was performed with t-test using SPSS software program (α = 0. 05).

The mean SBS values of Carisolv and handpiece groups were 19. 7 ± 6. 1 and 17. 3 ± 5. 5 MPa، respectively، with no statistically significant differences between the two techniques (p value = 0. 308).

Based on the results of the present study، the bond strength of Clearfil SE Bond adhesive to dentin after caries removal using the two techniques (Carisolv and handpiece) did not exhibit significant differences.

One of the complications of removable partial dentures is debonding of the acrylic resin from the cobalt-chromium framework. Several factors are involved in this chemical and physical bond. The aim of this study was to investigate the effect of applying primers and sandblasting on bond strength between the metal and the acrylic resin in mesh and ladder-like frameworks. In this in vitro study، 30 frameworks with ladder-like design (A) and 30 frameworks with mesh-like design (B) were fabricated. The mesh-like and ladder-like frameworks were each subdivided into three subgroups: 10 specimens in each subgroup were un-treated as the control group (A1 and B1); 10 specimens were sandblasted (A2 and B2)، and 10 were both primed and sandblasted (A3 and B3). Then the acrylic resin base was bonded to metal surfaces and the metal‒resin bond strength was examined by an Instron testing machine and recorded in Newton. Data were analyzed using two-way ANOVA and Tukey test (α = 0. 05). There were significant differences between the three preparation techniques (p value < 0. 001). There were no significant differences between the mean bond strength values of ladder (785. 90 ± 207. 24N) and mesh type (718. 60 ± 216. 83N) frameworks (p value = 0. 133). Mean bond strength values of sandblasting and primer (947. 38 ± 86. 18 N) were significantly higher than those of sandblasting (749. 5 ± 142. 11 N) (p value < 0. 001). Sandblasting resulted in a significantly higher bond strength values compared to the control group (539. 47 ± 164. 09 N) (p value < 0. 001). Sandblasting alone resulted in a 38% increase in bond strength whereas applying primers with sandblasting increased bond strength by 75%. Sandblasting and primer significantly influence resin‒metal bond strength. Subjecting frameworks to a combination of priming and sandblasting produces the highest bond strength.

Considering the diverse uses of panoramic radiographs in dentistry، precise measurement of dimensional changes in each region of the radiograph can be effective in their clinical application. The aim of the present study was to examine the horizontal and vertical magnification of different areas of the jaws on analog panoramic radiographs. In this descriptive analytical study، 10 dry human skulls were marked by gutta-percha in different horizontal and vertical dental areas (central، lateral، canine، first and second premolar and first and second molar areas) and radiographs were then prepared from each skull using two analog panoramic machines (Planmeca XC and Soredex Cranex-Tome). Measurement on the skulls and radiographs were independently carried out by two observers. Data were analyzed by SPSS 18 software. Horizontal and vertical magnifications were computed in each region and compared with the values reported by the manufacturer at a significance level of 95%. Inter-class correlation coefficients (ICC) were calculated for each observer and between observers. The magnification means in transverse and vertical dimensions with Planmeca XC were 1. 04 ± 0. 15 and 1. 15 ± 0. 08، respectively، yielding differences of -0. 046 and -0. 15 from the values reported by the manufacturer. The magnification means in transverse and vertical dimensions with Soredex Cranex-Tome were 1. 05 ± 0. 15 and 1. 17 ± 0. 08، respectively، yielding differences of -0. 12 and -0. 24 from the values reported by the manufacturer. The intra-observer and inter-observer ICCs were 98% and 95%، respectively. Under the limitations of the present study، the magnification means in vertical and horizontal dimensions in various regions of the jaws، reported by manufactures، are reliable.

The use of hand-held portable x-ray units is on the rise in dentistry. X-ray equipment operators are worried about being exposed to radiation-induced risks. The aim of this study was to determine the amount of scattered radiation around PORT-XII portable dental radiography device.

In this descriptive study radiation dose measurement was carried out at 6 positions around the PORT-XII radiography unit (over، under، right، left، behind and front at a distance of 1 meter from the unit). Dosimetry was carried out by the Geiger-Muller counter. The setting for all the exposures consisted of 60 kVp، 2 mA، and 0. 3 s and Primax (class E) films. In the current study 15 patients were evaluated. Study data was compared to the annual maximum permissible dose. Data were analyzed by paired t-test and one-way ANOVA using SPSS 18 (α = 0. 05).

The measured backscattered radiation at 6 positions around the PORT-XII unit at a distance of 1 meter far from the equipment was below the annual maximum permissible dose of 50 msv. The backscattered radiation behind the PORT-XII unit was less than other sides and the mean was 0. 98 ×10-3 msv، demonstrating a significant difference from other sides (p value < 0. 001). However، other sides were not significantly different from each other (p value = 0. 169). The mean of the measured dose was 0. 002 msv near the unit and 0. 004 mR 1 meter away from the unit.

Based on the results of the present study، the measured dose around PORT-XII unit was well below MPD.

Long soft tissue anesthesia in dentistry results in problems such as difficulties in speaking and swallowing، inadvertent biting of soft tissues and a temporary negative influence on patients’ quality of life. Intra-oral injection of phentolamine mesylate is used to decrease local anesthesia duration. Mucoadhesive film containing phentolamine mesylate can be used as a needle-free form of drug to reduce tissue damage and local pain. The aim of this study was to design and evaluate a two-layer film of phentolamine mesylate with one layer containing drug and the other containing a resistant layer for diffusion of the drug in one direction. In this experimental study، mucoadhesive polymers and drug were used in the first layer and ethyl cellulose was used in the second layer. Disintegrating agents، osmotic agents and plasticizers were used in first layer. The prepared films were evaluated in terms of physical and pharmaceutical properties including flexibility، thickness، ex vivo adhesion، disintegration time، superficial pH، and drug content and in vitro drug release. The formulation was selected based on standards of previous studies. Of 44 different formulations the mucoadhesive film prepared by mixing PVA and NaCMC polymers and sodium starch glycolate disintegrating agent was desirable in terms of pharmaceutical features and had the highest drug release rate (96%). EC100cps polymer and alcohol as a solvent were selected in order to prepare the second layer. In order to reverse soft tissue local anesthesia in dentistry، producing of phentolamine mesylate mucoadhesive film is possible with suitable pharmaceutical effects.

Endodontically treated teeth are weaker than intact teeth. Use of fiber-reinforced composite resin posts in the treatment of these teeth can result in an integrated post-and-core complex because of the similarity of physic-mechanical properties of these posts to dentin. The aim of this study was to evaluate fracture resistance of teeth restored with three different types of glass fiber posts. Thirty extracted human upper central incisor teeth، which were similar in size، were selected and divided into three groups (n = 10). In all the groups the crowns were sectioned 2 mm above the CEJ and endodontic treatment was carried out. Then HtCo، Anthogyr، Sevenska، and posts were cemented with Panavia cement in groups 1، 2 and 3، respectively، and restored with composite resin. Fracture resistance of the samples was measured in a universal testing machine. Data were analyzed with ANOVA (α = 0. 05). The means of fracture resistance values in HtCo (1)، Antthogyre (2) and Sevenska (3) groups were 564. 74 ± 213. 59، 629. 12 ± 390. 33 and 779. 84 ± 282. 59 N، respectively، with no significant differences between the groups (p value = 0. 285). Restorations carried out with Iranian fiber glass post (HtCo) exhibited fracture resistance similar to two other imported posts.

Dental caries is one of the most important oral cavity diseases، which initially appears as a “white spot lesion” due to the loss of mineral content. The aim of the current study was to evaluate and compare color changes in sound and demineralized enamel after treatment with remineralizing agents. In this in vitro study، 96 sound maxillary incisors were randomly divided into 6 groups (n = 16). Groups 1، 2 and 3 were designated as sound enamel، with groups 4، 5 and 6 as demineralized enamel. The teeth in groups 4، 5، and 6 were demineralized to simulate white spot lesions. Subsequently، Groups 1 and 4 were treated with CPP-ACFP (Casein Phosphopeptide-Amorphous Calcium Fluoride Phosphate)، Groups 2 and 5 with CPP-ACP (Casein Phosphopeptide-Amorphous Calcium Phosphate)، and Groups 3 and 6 with a fluoride mouthwash. All the specimens’ color coordinates were recorded by means of spectrophotometry (based on CIELAB criteria) before and 3 weeks after treatment. Data were analyzed with SPSS 16. 0 using one-way، two-way، and repeated measures ANOVA (α = 0. 05). The mean ΔE for the demineralized groups was 10. 75 ± 4. 21. In the treatment phase، the means of ΔE were 18. 09 ± 7. 53 and 7. 94 ± 4. 35 for the demineralized and sound enamel groups، respectively، with no significant differences between the three treatment agents (p value > 0. 05). Within the limitations of the present study، it seems that treatment with remineralizing agents can cause a significant color change in sound and demineralized enamel، finally resulting in a more acceptable overall esthetic appearance of teeth with white spot lesions. Key words:

Traumatic dental injuries occur in children with great frequency because of falls in schools، fighting or falls during riding a bike، making it necessary to visit a dentist. One of the most serious dental injuries is avulsion in which the tooth completely comes out of the dental socket. In the clinical view the socket is empty or it is filled by a clot. These injuries make the child and the parents extremely anxious because if avulsion is not managed immediately and properly it has dangerous side effect، like loss of the permanent tooth، esthetic problems، loss of self-confidence، malocclusion and malnutrition. The aim of this literature review was to collect the latest guidelines about avulsed teeth. Review Report: Electronic search was carried out in Pubmed and Medline for controlled randomized clinical trials and review articles and American Association of Endodontists guidelines about diagnosis، treatment plan and follow-up of avulsed teeth. Articles were collected until the end of March 2013. Since general dentists face this condition more than others they are in the first line of treatment such children and can pervert most of the side effects with proper treatment. Therefore، having the latest knowledge about diagnosis، treatment plan and follow-up of avulsed teeth is essential for all the general dentists and specialists.

Oral squamous cell carcinoma is the tenth most common malignant neoplasm. One of the key roles of general dental practitioners is the early diagnosis and referral of patients with oral lesions suspected of being malignant. The aim of this study was to review oral precancerous lesions and the steps necessary for their early diagnosis، especially in the general dental office. Review Report: In this study، PubMed، EBSCO، ISC، Google Scholar and other relevant database were searched for clinical features and differential diagnosis of premalignant lesions from 2000 to 2012. General dental practitioners may encounter oral lesions with a potential for malignancy during routine clinical examinations. Oral squamous cell carcinomas might have different clinical features. Application of toluidine blue staining and other new methods have been suggested for their early diagnosis. However، in some cases biopsies are necessary for definitive diagnosis.

Early diagnosis of oral premalignant and malignant lesions decreases tissue destruction and improves the treatment outcome and prognosis. Therefore، general dental practitioners have a key role in the early diagnosis and referral of patients with oral lesions.