Objective: Tooth eruption has been a subject of extensive scientific studies; and literature is replete with different mechanisms of migration of a tooth from its bony crypt into the oral cavity. However, there is no common ground on the nature and source of the propelling force among the proponents of these theories. The purpose of this study was to explore the possibility of unifying the currently accepted mechanisms of tooth eruption under single theory.Materials and Methods: A detailed and systematic analysis, synthesis and integration of the findings from relevant scientific studies on mechanisms of tooth eruption were conducted using search engines such as Medline and PubMed. During the search, phrases such as “tooth eruption”, “tooth eruption theories”, “tooth eruption and neuromuscular system”, “mechanosensationand mechanotransduction” were used. Scholarly published articles on tooth eruption process from 1940 to 2015 were selected based on specific inclusion and exclusion criteria.Results: The findings from these relevant scientific studies clearly showed a common factor – a propelling force during the different phases of tooth eruption. This propelling force has beenexplained in terms of piezoelectricity, mechanosensation, mechanotransduction, biomechanical, biochemical, cellular, molecular and enzymic activities involving the jaws and other facial bones during eruption of the developing tooth.Conclusion: “Neuromuscular theory of tooth eruption” or “unification theory of tooth eruption” is based on neuromuscular forces, arising from muscular contractions in the orofacial region.These neuromuscular forces are being proposed as the origin of the propelling force during the different phases of tooth eruption process.Key words: Mechanosensation, Mechanotransduction, Neuromuscular, Theory, Tooth eruption.

Objectives: This study sought to assess the effect of low-level laser (LLL) on pain and trismus after impacted mandibular third molar surgery.Materials and Methods: This double blind controlled clinical trial was conducted on 40 healthy patients with no underlying disease and impacted mesioangular mandibular third molarswith the same level of difficulty. The patients were divided into two groups of intervention and control using block randomization. In the intervention group, LLL was intraoral irradiated tothe surgical site 10 minutes after suturing from 1cm distance. Sham laser was used in the control group. The patients were provided with postoperative instructions and were scheduled for visits at two and seven days postoperatively to fill out a questionnaire and for suture removal. Level of painwas determined using a pictorial visual analog scale (VAS) and degree of trismus was measured in millimeters. The data were analyzed using SPSS.Results: Mouth opening in the laser group was greater than that in the control groupat two days postoperatively, which indicates the efficacy of laser for prevention of trismus. The changes inmouth opening were significant at baseline and at two and seven days postoperatively in the two groups (P=0.000); however, the trend of change was equal in both groups. No significant differences were noted in any variable between patients over and under 24 years of age in the two groups except for the amount of drug intake at two days post-surgery.Conclusion: The results showed that laser irradiation efficiently decreased trismus and improved mouth opening during the first seven days post surgery. Thus, laser irradiation can shortenthe course of recovery after impacted mandibular third molar surgery.Key words: Gene therapy, Dentistry, Viral vector, Stem cell.

Introduction: Lateral osteotomy is a major part of rhinoplasty for remodeling external facet of the nose and narrowing of nasal base and dorsum after removal of the hump with the edema and ecchymosis being the major sequels of the operation. The present study compared post-operative edema andecchymosis and mucosa tears between internal and external osteotomy techniques.Materials and Methods: In a prospective double-blind randomized clinical trial, 20 cases underwent internal and 20 cases underwent external lateral osteotomies from the candidates of rhinoplasty in the Gundi Clinic. Mucosal tears were measured by millimeters and edema and ecchymosisseverity were scored by a 4-scaled measure on 7 days after surgery. Mucosal tears of the groups were analyzed by Exact Fisher test while the edema and ecchymosis scores of both groups were subjected to Mann-whitney U test.Results: In the internal and external techniques; 6 (30.0%) and 4 (20.0%) showed mucosal tears on both sides respectively. In the right sides of the patients underwent internal osteotomy; the edema and ecchymosis grades of +, ++, +++ and ++++ were observed in 1 (5.0%); 9 (45.0%); 8 (40.0%)and 2 (10.0%) while these values were 2 (10.0%); 8 (40.0%); 8 (40.0%) and 2 (10.0%) in the left sides in these patients. In the right sides of the patients in external group; edema and ecchymosis grades of +, ++, and +++ were shown in 3 (15.0%); 12 (60.0%); and 5 (25.0%) while the valueswere 4 (20.0%); 11 (55.0%); and 5 (25.0%) in the left sides of them. Although with lower grades of associated complications in the external technique; no significant differences were observedbetween 2 modalities.Conclusion: Although with no significant differences; external osteotomy seems to be the approachof choice for the plastic surgeries of the nose and correction of bone deformities due to the lower values of edema and ecchymosis and mucosal tears as well as the simple performance of the technique.Key words: Rhinoplasty, Internal lateral osteotomy, External lateral osteotomy, Mucosal tears, Edema and eccymosis.

Background and Aim: Proper and immediate management of traumatic dental injuries dependshighly on dentists’ knowledge. The aim of this study was to evaluate knowledge of dentistry students at universities of Tehran about managing traumatic dental injuries.Materials and Methods: The participants of this cross-sectional study were senior year students at dental faculties of four universities of Tehran, Iran (Tehran University, Islamic AzadUniversity, Shahed University and Shahid Beheshti University) in 94-95 (2016). In this study,anonymous questionnaires were distributed among students; the content of these questionnaires were obtained from previous standardized ones, and were re-evaluated. The questionnaire was consisted of questions regarding background information (5 questions), traumatic dental injuries (TDI) treatment history (2 questions), and knowledge questions (10 items). Class attendance records were obtained from educational assistants of these four universities in order to distributequestionnaires. After the questionnaires were filled, the answers were scored and the results were analyzed using descriptive tables and linear regression model in SPSS software.Results: In this study 66 male students (45.20%) and 80 female students (54.79%) filled the questionnaires which made a total number of 146 participants. The highest grade point average(GPA) for the participants was 19 and the lowest was 12. The answers to TDI knowledge were scored on a scale of 0-12. Participants mean score was 5.48 (SD= 2.3) for TDI knowledge section (of 12). Students of Tehran and Shahid Beheshti University had answered the questions better.Marriage status and trauma treatment experience, gender and age were not significantly associated with the scores for TDI knowledge.Conclusions: The low percentage of correct answers to the questions indicates the need to improvethe information of the students. Novel student-centered teaching methods are necessary to provide an effective learning process for TDI treatment.Keywords: Dental trauma, Management, Knowledge.

Background and Objectives: Temporomandibular disorder (TMD) refers to chronic pain of the temporomandibular joint (TMJ) associated with headache, neck pain, shoulder pain or back pain. The origin of these pains may be related to TMD. Many patients with chronic headache undergodifferent treatments for long periods of time with no cure. These headaches can be treated with proper diagnosis. This study aimed to assess the prevalence of TMD in patients with chronic pain.Materials and Methods: In this cross-sectional study, the prevalence of TMD was evaluated in 119 patients with chronic headache. Patients with headache for more than 6 months and those whose headache did not improve with medication were included. The research diagnostic criteriafor temporomandibular disorders RDC/TMD (AXIS I, AXISII) questionnaire was used for assessment of TMD. Independent t-test was used to assess the correlation of TMD with headache and age. Chi square test was used to compare males and females.Results: A total of 119 patients with a mean age of 36.14±10.86 years (range 18-65 years) were evaluated. Of patients, 30% were males and 70% were females. The prevalence of TMD was 66%.The prevalence of mayofacial pain dysfunction syndrome (MPDS) was 11%. The prevalence of pain, clenching, trismus and clicking was 15.1%, 4.2%, 5% and 10.1%, respectively.Conclusion: The prevalence of TMD was high in patients with chronic headache. Thus, assessment of TMJ is recommended in diagnostic workup and treatment of patients with chronic headache.Keywords: Temporomandibular disorder; Chronic pain, Headache.

The aim of this study was to present and review retromandibular anteroparotid approach and to evaluate its efficacy and safety in reduction and fixation of subcondylar fractures.Materials and Methods: In the period between January 2013 to February 2014, 10 patients with the age range of 17 to 41 years with a diagnosis of subcondylar fracture at Sina General Hospital,Iran, underwent open treatment of subcondylar fractures by retromandibular anteroparotid transmasseteric approach.Results: Occlusion status was evaluated by observing the dental contact by articulating paper and also as subjective by the patient, all patients had proper occlusion. 4 cases (40%) at the end of the first week after surgery complained of joint pain during the touch, at last follow-up, none of the patients had tenderness. All patients were normal at 6 months after surgical treatment in terms of mouth opening. Facial nerve was maintained in all patients except only one case (10%) thatweakness was observed in buccal branch of the facial nerve after surgery which was resolved completely after the 6-month follow-up and had returned to normal status. Also, there were no signs of complications of salivary glands, such as salivary fistula, sialocele or postoperative infection. Scars caused by surgical incision were barely recognizable in patients..Conclusion: Due to results of this paper, rigid fixation of subcondylar fractures can be performed best with transmasseteric anteroparotid method causing least complications and optimumresults.Key words: Mandibular condyle, Mandibular fractures.

The occurrence of epidermoid and dermoid cysts in the oral cavity is extremely rare accounting 0.01% of all cysts. In our case report we hereby present a large epidermoid cyst in the floor ofmouth imitating a plunging ranula. A 26-year-old female reported to us with a complaint of a swelling below the tongue since 2 year. On examination there was a swelling in the left side of thefloor of the mouth, with anextra oral component in the submental area, the patient underwent surgical removal of the mass under local anaesthesia. Diagnosis of an epidermoid cyst was confirmedby the histopathological report.

Ewing Sarcoma (ES) of the mandible is a rare malignancy with poor prognosis which can be misdiagnosed as odontogenic inflammatory lesions or infections. We present a 7-year old male childwhich had been previously misdiagnosed and treated as an odontogenic abscess. This reported case describes the clinical, radiological and histopathological findings of oral ES with difficultiesin management.

This report describes the case of a 25-year-old female patient who initially was undergone of canine distalization and orthodontic space opening for replacement of congenitally missing lateralincisors. Then she received dental implants each side and after the healing period, cement retained prostheses was fabricated and delivered. Despite the fact that all the factors seemed fine, the rightlateral implant failed after four months of cementation.Dental implant failure, especially in prosthetic phase, is a challenging issue in prosthodontics and it is important to find out the etiologies and associated factors. This case report discusses the probable reasons of early loading failure of cement retained implant restoration.Key words: Implant failure; lateral incisors missing; orthodontic space opening; osseointegration.