مجله تحقیق در علوم دندانپزشکی
سال یازدهم شماره 4 (پیاپی 42، زمستان 1393)

The fluoride released in oral cavity plays an effective role in preventing carries in lateral walls of the restoration cavities and remineralization of initial lesions. Dental materials are considerably different regarding the amount of fluoride release. This study aimed to determine the amount of fluoride release from three self-cure glass ionomer cements, Fuji I, Fuji Plus and SDS in distilled water. In this experimental study, 8 disc-shape specimens (3×10mm) were prepared from three glass ionomers, Fuji I and Fuji Plus (CG, Japan) and SDS (Iran). Eight specimens of each material were placed in 7ml of distilled water and were stores in incubator at 37oC. The amount of fluoride release was measure at 1, 3, 7, 14, 28 and 56 days using a fluoride ion-specific electrode (Metrohm, Switzerland). Data were analyzed using repeated measurement ANOVA and LSD tests. The pattern of fluoride release was similar for the three materials. The amount of released fluoride from the three material in day 1 was considerably greater than the other days (Fuji I=28.07±0.26, Fuji Plus=35.97±0.19, SDS=41.08±0.36), followed by a gradual decrease over the study period. The least amount of fluoride release was recorded on day 56. The difference between the amount of fluoride release from the three glass ionomers was statistically significant (P=0.0001). In addition to revealing a statistically significant difference between the three glass ionomers in terms of fluoride release, the results of this study suggests using SDS glass ionomer in patients susceptible to caries.

Several problems have been reported regarding the retention and longevity of the attachments of implant-supported overdentures. Few studies are available in this regard. This in-vitro experimental study evaluated the effect of disto-labial inclination of implant and attachment on retention and longevity of implant-supported overdentures. In this experimental study, 40 specimens in 8 groups were evaluated. Four mandibular edentulous models and related dentures were identically fabricated. Two implant analogues (Dentium, South Korea) were placed in each model. Analogues were placed at disto-labial inclinations of 5, 10 and 15 degrees. In the control group, analogues were placed parallel and at 90 degrees angle to the edentulous ridge.Locator abutment (Dentium, South Korea) with red retainer was placed on each implant analogue. Each specimen was loaded by 3000 insertion and removal and 2000 thermal cycles. The retention of each specimen was measured after each 500 cycles with UTM (SANTAM, STM20). Data were analyzed by Repeated Measure ANOVA and TUKEY tests.The maximum initial retention before thermo-cycling was found in specimens with 5 degrees of inclination (36.4±1.51 N). After thermo-cycling, the maximum retention was found in specimens with 15 degrees of inclination (30.7±1.11 N). The minimum retention was recorded in the group with 10 degrees of inclination in both conditions (17.18± 0.92 N). No significant difference was found between 5 and 15 degrees inclinations according to Repeated Measure ANOVA and TUKEY tests. But the retention in these inclinations was significantly higher than 0 (control) and 10 degrees inclinations. (P<0.001). Inclination of implant and attachment has a positive effect on the retention and longevity of overdenture in a way that by increasing the inclination to 15 degrees, the retention increases but wear-down rate and retention loss also increase simultaneously.

Failure of restored teeth after endodontic treatment is one of the challenges faced in restorative dentistry. Premolar teeth are more likely to fracture due to exposure to tensile stress and inappropriate anatomical shape. Therefore, the aim of this study was the comparison of the fracture resistance of maxillary premolars which were restored with composite resin, composite resin with glass ionomer lining and composite resin reinforced with fiber post. In this experimental study, 60 extracted human maxillary premolars were randomly divided into 4 groups of 15: Composite resin without bonding (1), Composite resin+ glass ionomer lining (2), Composite resin+ single bond 2 (3) and Composite resin+ Fiber post (4). The teeth were prepared by MOD design with palatal cusp reduction. The samples were placed in a chewing simulator and went under a 30 N force for 1200000 cycles. The threshold of compressive resistance was measured in MPa. Also, fracture patterns were assessed divided by restorability and non-restorability. ANOVA test was used for statistical analysis of data in all groups and post-hoc TUKEY test was used for two by two comparisons. The threshold of force resistance significantly increased from group 1 to 4 and the difference among all groups was strongly significant (p = 0.000). Restorable fracture pattern followed an ascending order from group 1 to 4 which was reversed for unrestorable pattern with no significance. (P> 0.05) Composite resin restoration reinforced with fiber post can increase the fracture resistance of endodontically treated premolars but the number of unrestorable fractures also increases with the use of these posts. Fracture strength and fracture patterns obtained through usage of composite resin restorations in endodontically treated teeth are appropriate.

Different fluoride products such as gels, mouthwashes, toothpastes and varnishes have been used to increase tooth resistance against dental caries. Among these, fluoride varnishes gained more importance due to their advantages. The present in-vitro study aimed to measure the amount of fluoride uptake into enamel from Sultan and AriaDent varnishes. In this experimental in-vitro trial, 40 fresh premolars were selected and sectioned into two mesial and distal halves. The samples were divided into 2 groups (n=20) and were exposed to either AriaDent or Sultan varnish products for one hour. Samples were stored in artificial saliva at 37° C for 24 hours and then were etched with 1 M acid perchloric for 30 seconds. After etching the window surfaces were washed by 0.2 M Potassium hydroxide (KOH). Sampling was done using acid etch enamel biopsy technique and fluoride and calcium contents were measured by potentiometer and spectrophotometer devices. Data were analyzed using T-Test. Enamel fluoride uptake in the specimens exposed to AriaDent and Sultan varnishes were 3.27±1.89 ppm and 3.41±1.34 ppm, respectively. The calcium content of the enamel specimens exposed to varnish was 82.02±52.84 ppm for samples exposed to AriaDent and 71.11±52.68 ppm for those treated with Sultan. No significant difference was found between two varnishes regarding the fluoride uptake into enamel (p=0.36) or calcium content. (p=0.34)It seems that local fluoride therapy with both varnishes (AriaDent and Sultan as the standard varnish) is equally effective.

The purpose of this study is to evaluate the diagnostic accuracy of direct digital radiography with and without using sharpening tool of digital radiography software in detection of inter-proximal enamel caries in premolar teeth. In this in-vitro study, 80 sound premolars extracted due to orthodontic treatments were fixed in two blocks with putty impression material in XCP film holder in a way that 2 teeth were in upper jaw and two in lower jaw. Bitewing digital radiographs were taken and sharpening tool of digital software was applied on them. Then, a cavity was shaped on proximal surface of one randomly selected tooth from each block. At this stage, digital radiographs were again taken from blocks as mentioned above. 80 obtained images were printed 1:1 on film and were evaluated by an oral and maxillofacial radiologist. Data were analyzed by proportion test and kappa weighted test. Positive predictive value and negative predictive value for direct digital radiography was 97% and 84.8% and after applying sharpening tool was 91.2% and 80.4%. Kappa weighted rate for reader was 0.85. Proportion test showed that this difference is not statistically significant. (p<0.4) Application of sharpening tool of digital radiography software does not improve the detection of inter-proximal enamel caries.

Hyoid is the only bone that has no bony articulation. It is connected to muscles and ligaments. Therefore, its position can be associated with head posture and different oral functions. The aim of this study was to evaluate the hyoid bone position in different vertical and sagittal jaw dysplasias. In this descriptive study, standard digital lateral cephalograms of 200 patients in the age range of 18 to 25 years were selected and subjects were divided into 5 groups based on vertical and horizontal facial growth pattern: group1: Class I, normal face, group 2: Class II, normal face, group 3: Class III, normal face, group 4: Class I, short- faced, group 5: Class I, long-faced. Hyoid bone position was analyzed by View box4 software. The anterior-posterior position of the hyoid bone was significantly backward in groups 2 and 5 compared to groups 3 (P=0.001) and 4 (P=0.001). However, the sagittal position of this bone in groups 2 and 3 was comparable to groups 5 and 4. The vertical position of hyoid bone was significantly upward in groups 2 and 4 compared to groups 3 (P=0.001) and 5 (P=0.001) but this position was significantly downward in groups 2 and 5 compared to groups 4 (P=0.001) and 3 (P=0.001). The axial inclination of this bone was comparable among subjects with different sagittal jaw dysplasias. This inclination was significantly more horizontal in group 4 compared to group 1 whereas in group 5, hyoid bone was more oblique.(P=0.001) Among subjects with different sagittal jaw dysplasias, the anterior-posterior position of the hyoid bone in Class II and Class III subjects was more posterior-superior and anterior-inferior compared to Class I subjects. Among subjects with different vertical jaw dysplasias, the hyoid bone in groups 4 and 5 was more anterior-superior and posterior-inferior respectively compared to normal-faced subjects.

Periodontal destruction occurs in an episodic fashion, with periods of exacerbation and quiescence. It is therefore important to diagnose periodontal diseases in active phase. Various diagnostic markers have been identified in GCF and saliva. The aim of this study was to compare the salivary and GCF levels of alkaline phosphatase (ALP) in patients with periodontitis, smokers with periodontitis and healthy subjects. In this descriptive study 90 subjects aged 30-50 without any apparent systemic disease were chosen and divided to 3 equal groups: smokers with periodontitis, non-smokers with periodontitis and healthy subjects. In healthy subjects, GCF samples were collected from gingival sulcus. In patients with periodontitis, GCF was collected from pockets of 5-7 mm of depth. About 5 ml of un-stimulated whole saliva was collected from all subjects. All GCF and salivary samples were sent to the laboratory for ALP measurement. ANOVA and Tukey's tests were used for statistical analysis. The results of this study showed that the mean level of ALP in saliva and GCF was higher in the first and second groups compared to the third group. The mean level of ALP in GCF was higher in the first group compared to the second group. The mean level of ALP in saliva was not statistically different between the first and second group. It is possible to use both GCF and salivary levels of ALP as diagnostic markers for periodontitis. Higher levels of ALP in GCF samples of smokers with periodontitis could explain the higher rate of alveolar bone destruction in smokers.

Revascularization therapy by using Platelet-Rich Fibrin can be a suitable choice for revitalization of immature necrotic teeth as it improves root formation process, thickening of dentinal walls and apical closure.Summary: A 13-year-old girl with a history of trauma in tooth #21 and signs of pulp necrosis referred to the endodontics department of faculty of dentistry of Islamic Azad University. Intraoral radiograph showed immature root with open apex and periapical rarefaction. Access cavity was prepared and the root canal was irrigated with 20 ml of 1/25% sodium hypochlorite solution for 5 minutes and with normal saline. Equal proportions of Ciprofloxacin (tablet, 500mg), Metronidazole (tablet, 500mg) and Cefaclor (capsule, 500mg) were mixed and placed inside root canal for 4 weeks. Then, the canal was irrigated with 17% EDTA. 8 ml of patient's whole blood was centrifuged for preparation of PRF clot. PRF clot was placed inside the root canal up to CEJ level. MTA of 3mm thickness was placed directly over the PRF clot and tooth was temporarily restored. After 3 days, the tooth was double sealed with Glass Ionomer cement and composite resin. Clinical examinations at 1, 3 and 6 months after, revealed the resolution of periapical lesion, further root development and apical closure. PRF clot is an ideal scaffold for regenerative endodontic therapy in necrotic immature teeth as it contains growth factors and can enhance cellular proliferation and differentiation of stem cells.

Neurofibroma is an uncommon lesion in the oral cavity. Most reported cases are multiple and associated with the generalized neurofibromatosis syndrome. Rarely, neurofibroma is formed as a solitary lesion and is not associated with the syndrome. To our knowledge, only four cases of solitary neurofibroma have been reported in the literature, which makes the clinical diagnosis difficult.Case Report: We report a case of solitary oral neurofibroma in the lower labial mucosa of a 43-year-old woman. These patients need regular follow-ups in order to identify recurrences and probable ancillary features of neurofibromatosis syndrome which may be life-threatening to the patient. Solitary neurofibroma should be considered in the differential diagnosis of the Intra oral nodules beside more common lesions including fibroma, mucocele and pleomorphic adenoma.