JOURNAL OF RESEARCH IN DENTAL SCIENCES
Year:2008 | Volume:5 | Issue:1|Papers Count:8

Background and aim: Results of Implant therapy have always been evaluated on the basis of radiographic and clinical assessments such as percussion, focused only on determination of peri-implant bone resorption and implant failures. These measurements are qualitative only and could not be considered as quantitative and reliable scales for the evaluation of stability; So they could not be statistically analysed. These difficulties could be overcome by using Resonance Frequency Analysis (RFA).RFA could be considered as a proper comparable measurement in evaluation of implant stability. This study aimed to evaluate and determine the stability of over denture loaded implants in a number of private clinics during 2006 -2007.Materials and Methods: This cross – sectional study was conducted on 13 patients provided with Swiss plus implant Therapy loaded by over dentures for the first step, each patient was evaluated regarding Implant Quality health Scale and put into one of five groups. Abutments were then removed and fixtures were evaluated by Osstell Mentor Instrument following the attachment of Smart peg to fixtures, Implant Stability Qoutient was then determined. Sampling was done in a sequential approach and obtained data were statistically analyzed using X2 and t-test.Results: Fourty three implants were evaluated in 13 patients, 21 in maxilla and 22 in mandible the mean I.S.Q.Equaled 70.36 ± 4.43 in maxilla and 79.1 ± 3.51 in mandible. The total mean ISQ (bimaxillary mean ISQ) equaled 84.36 ± 5.94.Conclusion: Regarding the obtained results, Over denture loaded implants are absolutely successful treatment plans in mandible, according to their higher ISQ compared to maxilla. It is also demonstrated that stability of implants at each step of treatment Procedure is influenced by primary stability during placement more than any other factors. Primary stability itself is mainly influenced by surgeon`s experience in the proper following of surgical protocol.

Background and aim: Recently, interest has been focused on pharyngeal dimensions because of a potential relationship between size and structure of upper airway and sleep-induced breathing disturbances Significant relationships between the pharyngeal structures and both dentofacial and craniofacial structures have been reported The aim of this study was to investigate the pharyngeal space dimensions in subjects with different malocclusion on the private clinic in Tehran in 2004-2008.Material and Methods: Cephalometric radiograph of 90 subjects (45 females and 45 males, aged 12–18 years) were included with the following criteria: no history of orthodontic treatment; breathing comfortably through the nose; normal vertical occlusal relationship (Max/Man planes angle 25.5o ± 5) and divided into three groups according to the ANB angle, group 1, skeletal Class I (ANB angle 1–5); group 2, skeletal Class II (ANB angle > 5); and group 3, skeletal Class III (ANB angle < 1). In addition, each group was divided into two subgroups according to sex. Statistical analysis was undertaken using analysis of 2-way ANOVA and least significant difference test. Lateral skull radiographs were traced on acetate paper and 12 hard and soft tissue cephalometric points were registered yielding 12 linear measurements.Results: Sex differences were found in Class I  and I and I subjects. The female has bigger SPAS/MIS and SPAS/IAS than male and the HRGN/C3H has increase in female than male. The distance between hyoid bone and C3 is longer in class III than class II.The height of airway space was reduced in Class II male subject compared with class I and III.We found relationship between ANB and position of hyoid bone to C3H and tongue length and tongue height.VAL was significantly reduced in class II subjects compared with class III & I in male.Conclusion: The results showed that malocclusion can change the position of hyoid bone to mandibular plan and C3H and the vertical air way space in male. We found the relation sip between ANB angle and tongue and hyoid bone.we found Sex differences were detected in superior airway and the position of hyoid bone.

Background and aim: Impacted canines require a combination of both surgical and orthodontic management. In this study 80 consecutively-treated patients with bone-impacted canines of the hard palate were evaluated to assess which radiographic or clinical factors influenced the exposure and movement of impacted maxillary permanent canines from the hard palate into the alveolar arch.Materials and Methods: This study assessed records of 80 patients treated surgically and orthodontically to align 146 bone- impacted canines of the hard palate. Potential influential factors (such as age, abnormality of the root, angulation of the canine and ratio of root formation upon admission) were documented. Radiographic records, documented clinical parameters and demographic data were assessed. The following measurements of canine position were made from the panoramic radiograph: 1- Angulation to the midline, 2- Ratio of root formation, , 3-Overlap of the adjacent incisor and 4-Apparent root anomaly or dilaceration. Whether the impacted canine had responded to surgical exposure and was orthodontically-aligned, or surgically removed and discarded was also recorded. The data was analyzed to assess to correlate significance.Results: 80 patients aged 11 to 24 (19 males and 61 females) with bone-impacted permanent canines of the hard palate were treated from 1994 to 2007 were chosen.all 80 patients had responded to surgical exposure and were orthodontically-aligned.none of patients had to have their impacted canine tooth surgically removed. Data analysis showed that the angulation of the crown to the midline and abnormality of the root influenced the treatment result..It also showed that the overlap of the adjacent incisor via the canine influenced the treatment result.Additionally, as the canine angulation to the midline increased, the canine was more likely to be removed (P< 0.001). The result also showed that the antero-posterior position of the canine did not influence the treatment result.Conclusion: Bone- impacted canines of the hard palate are more likely to respond to surgical exposure and orthodontic management if angulation to the midline is lower than 45 on the orthopantomogram. orthodontic alignment of an impacted upper permanent canine, based on radiographic and clinical information, seems to be more successful if the angulation of the impacted canine is lower than 45, the abnormality of the root does not exist and the overlap of the adjacent incisor via canine decreases to level 1 or 2 or does not exist at all.

Background and aim: The aim of this study was to evaluate the effect of etching solution containing various ratio of APF on orthodontic brackets bonding & enamel surface. Direct bracket bonding has many advantages & also disadvantages. The main problem is enamel loss & demineralization under & around brackets. Although phosphoric acide used for etching enamel before bracket bonding, it can be buffered by APF to decrease the adverse affect of it on enamel & this mixture may lead to adverse affect on shear bond strenght too. Unfortunately enamel damage may occure when debonding. It seams that the main benefet of using this kind of exprmental etching solution is to decrease the enamel loss during bonding & debonding procedures.MATERIALS & METHODES: 40 extracted human premolars from 10, 4 premolars extraction case paitiont were stored in 0/1% thymol solution. They were examined macroscophaly to insure that the buccal surface was both intact & caries-free & divided randomly in to 4 groups of 10 teeth. After cleaning the buccal surface with fluoride-free pumice each of them were etched with phosphoric acide solution containing 0, 25%, 50%, 75% of APF. Then brackets bonded to the teeth in the same situation as the company recommended. The dete were analysed with ANOVA Test & Tukey Post Hoc Test. After debonding test, the debonded enamel surface were examined using steriomicroscope with 10× magnification & the amount of adhesive remaining on enamel surface for each tooth was scored as the adhesive remained index & analyzed by Chi-square Test.RESULTS: The result of this research indicates that, shear bond strenght between enamel & adhesive decreased when APF added to etch solution. Also ARI decreased by adding APF to etch solution & the sit of bond failure in exprmental groups was between enamel & resin.CONCLUSION: Mixture of 25% APF+75% H3PO4 37% can be used in clinic as an etchant to minimize enamel loss during etching as well as debonding procedure with out compromising the requaried bracket bond strenght.

Background and aim: The application of fixed orthodontic appliances could be eventuated different imposition, For example: Develop the favorable condition to accumulation of streptococcus mutans (ms) and after that, enamel demineralization and an increased number of carious lesions, Predominantly in sits adjacent to brackets. This research has been designed and executed with the aim of surveying the dimension of effectiveness of the Listerine and Oral-B and Ortho-kin on the dimension of gathering of streptococcus mutans, which exist in plaque around the orthodontic brackets and in saliva and dimension of dental plaque.Material and Methods: Study with design of Double-Blind Randomized Cross over Clinical Trial on 25 orthodontic patients, who are classified to 6 groups, has been done. The dimension of streptococcus mutans in plaque and saliva with the side specific modified strip mutans technique and the dimension of PI has been measured before and after of using mouth rinse.Between using every mouth rinse with next mouth rinse has been considered a period of 3 weeks (washout) the data according to Wilcoxon and Kruskal Wallis statistics tests, have been judged.Results: The research has been done on 25 patients whose average ages were 19±6/3. They were 5 men and 20 women. The dimension of gathering of streptococcus mutans in every teeth based on mouth rinse, showed that the effect of Ortho-kin was better than Oral-B and Listerine (P<0/09). Also, according to kind of mouth rinse (percent of increase, percent of without changing and decrease), the changes of streptococcus mutans in person’s saliva, were in 3 similar groups, and there were not meaningful statistical differences (P<0/4). The dimension of changes in person's Bacterial plaque, based on kind of mouth rinse, showed that the effect of Ortho-kin was better than Oral-B and Listerine, too (P< 0/001).Conclusion: Ortho-kin in decreasing of streptococcus mutans and PI, was done better than Listerine and Oral-B. it is because of had Chlorhexidine.

Background and Aim: Due to the complications associated with fixation by titanium screws and plates in BSSRO surgery, the use of resorbable polymers have been increasingly recommended. Since there is not enough studies on this issue through the literature, this study aimed to assess the most appropriate stress distribution in fixation with resorbable plates after BSSRO surgery by FEA.Materials and Methods: This experimental study was performed on simulated human mandible using Ansys and CATIA softwares. The osteotomy line was applied to the simulated model and experimental loads of 75, 135 and 600 N were respectively exerted according to the natural direction of occlusal force. The distribution pattern of stress was assessed and compared for fixation with four-hole resorbable miniplate, two-hole resorbable miniplate and parallel miniplate using Ansys software.Results: Among the four simulated fixations, parallel miniplates showed the highest primary stability. Four-hole resorbable plates were also associated with sufficient primary stability and less trauma and cost for patients. Two-hole resorbable plates did not provide enough stability under 600 N.Conclusion: Polymer-based resorbable plates and screws (polyglycolic acid and D, L polylactide acid) in every three patterns, on masticatory loads after surgery, provides satisfactory primary stability in BSSRO surgery and the displacement of the osteotomy site fixed with this system was inconsiderable. the plates should at least have four holes and adjust in appropriate position (neutral zone) to provide sufficient primary stability. Therefore resorbabale fixation can be a good alternative for titanium fixation in BSSRO surgery.

Background and aim: regarding the prevalence of root proximity to the mandibular canal and importance of preventing nerve injury during surgery, the present study was held to evaluate the potency of panoramic radiographic findings in diagnosing the relationship between the mandibular canal and impacted mandibular third molar (M3) based on visiting inferior alveolar nerve (IAN) during surgical removal of impacted third molar in Tehran Azad University of Medical Sciences and two other private offices in 1386-87.Materials and methods: with diagnostic clinical trial design, Radiographic signs of 80 samples which had at least one present sign of the close relationship between IAN and M3 in the panoramic radiography were observed by a radiologist. All of the samples had surgical extraction of M3 by two experienced oral & maxillofacial surgeons, and records of IAN exposure were established during the surgey as the standard criteria. Statistical analysis was performed for radiological signs potency by ratio tests.Results: interruption of the white lines, diversion of the canal and narrowing of the canal had greater potency than the others and they have respectively positive predictive value of 67.9, 81 and 78.4 and negative predictive value of 85.2, 64.8 and 74.4 percent. According to a new finding, dimension of the angle which formed between the line tangent with canal and the line tangent with M3 root, had respectively a positive and negative predictive value of 76 and 93.3 percent.Conclusions: Considering all of the signs, angulation, depth and type of the impaction simultaneously may have a better diagnostic result. It is recommended to use the method of measuring formed angle between the line tangent of canal and root.

Background and Aim: According to the importance of trigemino cardiac reflex (TCR) and also prevention and management of this reflex in maxillofacial surgeries, the present study was held to evaluate the TCR In lefort I osteotomy. on patients who came to Surgical Department of Buali hospital and the private office in 1386-87.Material and Method: The study was held on 30 patients at the age of 18-39 which were candidate for osteotomy lefort I surgery. TCR was defined as a drop in mean arterial blood pressure (MABP) and heart rate (HR) of more than 10% to the baseline values before maxillary down fracture (D.F) and coinciding with D.F. Hemodynamic parameters such as HR and MABP evaluated with continuous monitoring in different times (before, during and after down fracture of maxilla). Changes in upon characteristics were analyzed.Results: 5 patients were excluded for different reasons and study was completed on 25 patients. Age of the patients was 24.6±1.6, 30% male, and 70% female. The mean HR fell 6.5% from a mean of 94.29±12.12 beats/min, before D.F to a mean of 88.08±13.6 beats/min during D.F, returning to a mean of 93.92±13.09 after D.F. The MABP fell 9.7% from to a mean of 103±15.89 mmHg before D.F to a mean of 92.99±15.19 during the D.F, returning to a mean of 99.69±13.123 after D.F. The HR and MABP after DF were not significantly different from baseline values before the DF. The mean HR drop of more than 10% to the baseline values before DF and coinciding with DF, in 25% of the patients, and also about the MABP, it fell in 45.8% of the patients.Conclusions and suggestions: The present results give evidence that stimulation or manipulation of maxillary branch of the trigeminal nerve can cause TCR, leading to a significant decrease in HR and MABP under a standardized anesthetic protocol. Further studies preferably with a multicenter design are necessary to confirm the nature, description. predisposing and triggering factors and other aspects of this seemingly physiologic phenomenon.