Orthodontic uprighting of a horizontally impacted third molar and protraction of mandibular second and third molars into the missing first molar space for a patient with posterior crossbites.

A 22-year-old woman came with a unilateral missing mandibular first molar and buccal crossbite. The open space was closed by protraction of the mandibular left second molar and uprighting and protraction of the horizontally impacted third molar using temporary skeletal anchorage devices, and her buccal crossbite was corrected with modified palatal and lingual appliances. The total active treatment time was 36 months. Posttreatment records after 9 months showed excellent results with a stable occlusion.

Role of microcracks in the pathogenesis of bisphosphonate-related osteonecrosis of the jaw.

OBJECTIVES: The aim of this study was to investigate the potential role of microcrack accumulation in the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (ONJ) through an animal model. MATERIALS AND METHODS: Twenty-four ovariectomized rats were randomly divided into a bisphosphonate group (n = 19) and control group (n = 5) and weekly injected with zoledronic acid and normal saline, respectively. After 6 weeks, surgical intervention was performed, and the injections were continued for eight additional weeks. Then, the animals were sacrificed, and ONJ lesions were inspected for the presence of microcracks using scanning electron microscopy. Measurements included bone dimension, number of cracks, crack length, and normalized indices; crack density (Cr.Dn) and crack surface density (Cr.S.Dn) were used for group comparison. RESULTS: Both number of cracks and crack length in the bisphosphonate group were greater than those in the control group (P < 0.05). Of the 19 rats injected with bisphosphonates, 13 rats (68.4 %) were classified into the ONJ group. Cr.Dn and Cr.S.Dn were significantly greater in the ONJ group than in the non-ONJ group, indicating accumulation of unrepaired microcracks (P < 0.05). Seventy-two percent of microcracks in the ONJ group conformed to the defined length that was considered significant according to a previous literature (30-80 µm); whereas 12 % of microcracks in the non-ONJ group were considered significant (P < 0.05). CONCLUSION: Accumulation of unrepaired microcracks was significantly associated with the development of bisphosphonate-related ONJ. Further research is required to determine the role of microcracks in the pathogenesis of bisphosphonate-related ONJ. CLINICAL RELEVANCE: Long-term bisphosphonates use may deteriorate the biomechanical and physiological bone integrity, contributing to the pathogenesis of bisphosphonate-related ONJ.

Which risk factors are associated with neurosensory deficits of inferior alveolar nerve after mandibular third molar extraction?

PURPOSE: Mandibular third molar extraction is a commonly performed procedure and is recognized as a relatively frequent cause of inferior alveolar nerve (IAN) injury. The aim of the present study was to investigate the specific risk factors for neurosensory deficits, including age, gender, impaction depth, angulation of the third molar, and various radiographic superimposition signs. MATERIALS AND METHODS: In a case-control study of patients who had undergone mandibular third molar extraction, a case group was developed of patients showing neurosensory deficits of the IAN, and a control group was formed of randomly selected patients without any neurosensory symptoms. Bivariate analyses were performed to assess the relationship between each variable and IAN injury. A multivariate logistic regression model was used to compute the odds ratios, P values, and predictive values of the radiographic superimposition signs. RESULTS: Of 12,842 total patients, the study group included 104 cases and 135 controls. The results indicated that older age and deeper impaction status were significant risk factors (P < .05). Darkening of the roots, deflection of the roots, narrowing of the roots, dark and bifid apexes of the roots, and narrowing of the canal were also significant risk factors. The positive predictive values ranged from 0.7% to 6.9% and the negative predictive values from 99% to 100%, with adjustment for the definitive prevalence of IAN injury (0.81%, 104/12,842 patients). However, the relatively low positive predictive value renders questionable the predictability of superimposition signs on orthopantomography. In the absence of specific radiographic signs, the risk of neurosensory deficit of the IAN could be negligible. The sensory symptoms disappeared after 6 months in 92.3% of the patients and 98.1% showed recovery after 1 year. CONCLUSIONS: The results of the present study have demonstrated a significant association between several risk factors and neurosensory deficits of the IAN after third molar extraction. With a case group of 104 patients, the number of subjects was significantly greater than that in previous studies, increasing the reliability of these results.

Clinical review of factors leading to perioperative dissatisfaction related to orthognathic surgery.

PURPOSE: The purpose of the study was to obtain information on factors leading to perioperative dissatisfaction of patients who undergo orthognathic surgery for dentofacial deformities. MATERIALS AND METHODS: A total of 44 patients who underwent orthognathic surgery between January 1, 2003, and September 30, 2005, were included in this study. All patients completed 21-item questionnaires, which were analyzed using the frequency distribution and the chi(2) test. RESULTS: The patients lost 6.4% of their body weight after 1-jaw surgery and 6.7% after 2-jaw surgery. The patients returned to their everyday life 4.8 weeks after 1-jaw surgery and 5.2 weeks after 2-jaw surgery. Restoration of sensory function after jaw surgery required almost 10 weeks. CONCLUSION: Written information about possible sequelae and the recovery period and patients' consent to the surgical procedure may be helpful in proper communication, which may reduce patients' perioperative dissatisfaction.

Clinical and pathologic features related to the impacted third molars in patients of different ages: A retrospective study in the Korean population.

BACKGROUND/PURPOSE: The surgical extraction of impacted third molars (ITMs) is a common surgical procedure in dentistry. If prophylactic removal of ITMs is beneficial, however, is a still disputed issue. The aim of this study was to analysis the pathologic changes in impacted third molars (ITMs) and adjacent teeth according to patient age groups in the Korean population to determine if the prophylactic removal of ITMs is to be supported or not. MATERIALS AND METHODS: A retrospective study of patients who underwent surgical extraction of impacted third molars was performed. The patients were divided into 5 groups according to their age. Each group was analyzed with respect to patients' chief complaints, specific pathologic conditions in ITMs, and the damage to adjacent teeth due to untreated ITMs. RESULTS: In this study, 2883 impacted third molars in 1109 patients were analyzed. The most common patients' chief complaint was pain, and the frequency of pain was significantly higher in older age groups. The frequency and severity of pathologic changes in ITMs and adjacent second molars due to ITMs were increased with advancing age. CONCLUSION: Based on the results of this study, we conclude that the prophylactic removal of ITMs that have a higher probability of pathologic changes can be considered to be a reasonable treatment modality in younger patients to reduce morbidity resulting from surgical extraction compared with patients who attained advanced age.

Biomarkers for Bisphosphonate-Related Osteonecrosis of the Jaw.

PURPOSE: The aim of this study was to investigate a possible biomarker for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in an animal model. MATERIALS AND METHODS: Forty-eight Sprague-Dawley rats were randomly divided into the bisphosphonate group (n = 36), who were injected once a week with zoledronic acid, and the control group (n = 12), who were injected once a week with saline. After 6 weeks, surgical intervention was performed, and injections were continued up to 8 weeks. Rats in the bisphosphonate group were then further classified to the ONJ group, and the non-ONJ group, and biomarkers, including CTx, Glu-OC, TRACP 5b, RANKL, and OPG, were assessed at baseline (T0), at surgical intervention (T1), and at sacrifice (T2). Histomorphometric analysis for quantification of osteoclasts was performed. RESULTS: Repeated measures analysis of variance revealed that TRACP 5b levels and the RANKL/OPG ratio were significantly decreased over time in the ONJ group compared with the non-ONJ group (p < .05). At T2, the area under the curve was 0.807 for TRACP 5b (sensitivity: 88.9%, specificity 66.7% at cutoff) and 0.765 for the RANKL/OPG ratio (sensitivity: 77.8%, specificity 62.9% at cutoff). TRACP 5b showed a lower least significant change (29.6%) with lower intra-assay coefficient of variability (CV; 6.32%) and interassay CV (11.20%) compared with those of the RANKL/OPG ratio (39.27%) and showed a higher signal-to-noise ratio (2.76) than that of the RANKL/OPG ratio (1.62). N.Oc/T.Ar and N.Oc/B.Ar demonstrated significantly decreased number of osteoclasts in ONJ group versus non-ONJ group. CONCLUSIONS: These results show that serum TRACP 5b and the RANKL/OPG ratio were possible biomarkers for BRONJ. These data may provide useful additional information for future ONJ research. Further studies are needed to validate these results in humans with ONJ.

Animal model for medication-related osteonecrosis of the jaw with precedent metabolic bone disease.

Despite the fact that the medications used to treat abnormal bone conditions often induce osteonecrosis of the jaw (ONJ), previous attempts to establish an animal model for ONJ have shown insufficient consideration for this important prerequisite for the development of the disease. The purpose of this study was to establish an animal model with the most common metabolic bone disease, osteoporosis. Ninty-six rats were randomly divided into ovariectomy (Ov) group (n=48) and sham-operated group (n=48). Six weeks after Ov or sham surgery, rats in each group were subdivided into bisphosphonate group (n=36 each) and control group (n=12 each) and injected with zoledronic acid and normal saline, respectively, once a week. After additional 6weeks, surgical intervention was performed, and the injections were continued for 8 more weeks. The animals were then sacrificed for further macroscopic, histological, histomorphometric, radiological, and bone biomarker investigations. As histologically determined, the Ov group (77.8%) showed higher ONJ prevalence compared to the sham group (47.2%; P<0.05). Micro-structural and histomorphometric assessments revealed that rats with ONJ (ONJ group) presented with deteriorated bone architectures with higher necrotic bone fraction and lower number of osteoclasts (P<0.05). Compared to the sham-operated ONJ group, the Ov ONJ group showed significantly lower values of Tb.N, Tb.Sp, Conn.D, N.Oc/T.Ar, and TRACP 5b and CTX/TRACP (P<0.05). The ovariectomized rat model in this study successfully mimicked human ONJ lesions with an underlying bone disease and showed different bone characteristics than that of the previous ONJ model. Based on the differences, further researches for investigating pathophysiology of ONJ, including various pharmacological responses for deteriorated bone environment, are required.

Leucocyte-rich and platelet-rich fibrin for the treatment of bisphosphonate-related osteonecrosis of the jaw: a prospective feasibility study.

Our aim was to assess the feasibility of using leucocyte-rich and platelet-rich fibrin (L-PRF) for the treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in a single group study. After treatment with L-PRF, the response of each patient was recorded 1 month and 4 months postoperatively. Further assessments were made of the site, stage, concentration of c-terminal crosslinked telopepide of type 1 collagen, and actinomycosis. Among the total of 34 patients, 26 (77%) showed complete resolution, 6 (18%) had delayed resolution, and 2 (6%) showed no resolution. There was a significant association between the response to treatment and the stage of BRONJ (p=0.002) but no other significant associations were detected. This study has shown that it is feasible to use L-PRF for the treatment of BRONJ, but the effectiveness cannot be judged with this study design. Randomised prospective trials are needed to confirm this.

Three dimensional finite element analysis of the stress distribution around the mandibular posterior implant during non-working movement according to the amount of cantilever.

PURPOSE: In case of large horizontal discrepancy of alveolar ridge due to severe resorption, cantilevered crown is usually an unavoidable treatment modality. The purpose of this study was to evaluate the clinical criteria for the placement of the aforementioned implant crown. MATERIALS AND METHODS: The mandible model with 2 mm thick cortical bone and cancellous bone was fabricated from CT cross-section image. An external connection type implant was installed and cantilevered crowns with increasing offset of 3, 4, 5, 6, and 7 mm were connected. Vertical load and 30° oblique load of 300 N was applied and stress around bone and implant component was analyzed. A total of 14 cases were modeled and finite element analysis was performed using COSMOS Works (Solid works Inc, USA). RESULTS: As for the location of the vertical load, the maximum stress generated on the lingual side of the implant became larger according to the increase of offset distance. When the oblique load was applied at 30°, the maximum stress was generated on the buccal side and its magnitude gradually decreased as the distance of the offset load increased to 5 mm. After that point, the magnitude of implant component's stress increased gradually. CONCLUSION: The results of this study suggest that for the patient with atrophied alveolar ridge following the loss of molar teeth, von-Mises stress on implant components was the lowest under the 30° oblique load at the 5 mm offset point. Further studies for the various crown height and numbers of occusal points are needed to generalize the conclusion of present study.

Changes of the Airway Space and the Position of Hyoid Bone after Mandibular Set Back Surgery Using Bilateral Sagittal Split Ramus Osteotomy Technique.

PURPOSE: Although there have been several studies of reduced airway space after mandibular setback surgery using the sagittal split ramus osteotomy technique, research on the risk factors for changes of the airway space is lacking. Therefore, this study was performed to examine airway changes and the position of the hyoid bone after orthognathic surgery, and to assess possible risk factors. METHODS: In this retrospective study, 50 patients who underwent posterior displacement of the mandible by the bilateral sagittal split ramus osteotomy technique were included. Changes of the position of the hyoid bone and the airway space were analyzed over various follow-up periods, using cephalometric radiography taken preoperatively, immediately after surgery, eight weeks after surgery, six months after surgery, and one year after surgery. To identify risk factors, multiple regression analysis of age, gender, body mass index (BMI), posterior mandibular movement, and the presence of genioplasty was performed. RESULTS: Inferor and posterior movement of the hyoid bone was observed postoperatively, but subsequent observations showed regression towards the anterosuperior aspect. The airway space also significantly decreased after surgery (P <0.05), and increased slightly up until six months after surgery. The airway space significantly decreased (ß=0.47, P <0.01) as the amount of mandibular setback increased. However, age, sex, BMI, and presence of genioplasty were not associated with airway reduction. CONCLUSION: The amount of mandibular set back was significantly associated with postoperative reduction of airway space. It is necessary to establish a treatment plan considering this factor.

Traumatic carotid-cavernous sinus fistula accompanying abducens nerve (VI) palsy in blowout fractures: missed diagnosis of 'white-eyed shunt'.

We report the case of a 32-year-old woman with bilateral blowout fractures. She presented with diplopia showing impaired abduction of the left eye soon after trauma. No other orbito-ocular signs, such as exophthalmos, ptosis, or chemosis, were found. Orbital reconstruction was performed, but no improvement in her ophthalmoplegia was observed after surgery. A carotid angiography showed that she was suffering from a posteriorly draining carotid-cavernous sinus fistula with isolated abducens nerve palsy. Coil embolization was conducted under the consultation of a neurosurgeon, after which her ophthalmoplegia resolved fully. This is a rare case of posteriorly draining carotid-cavernous sinus fistula without classic orbito-ocular signs, the absence of which may cause diagnostic confusion.

Modulation of osteoblastic/odontoblastic differentiation of adult mesenchymal stem cells through gene introduction: a brief review.

Bone tissue engineering is one of the important therapeutic approaches to the regeneration of bones in the entire field of regeneration medicine. Mesenchymal stem cells (MSCs) are actively discussed as material for bone tissue engineering due to their ability to differentiate into autologous bone. MSCs are able to differentiate into different lineages: osteo/odontogenic, adipogenic, and neurogenic. The tissue of origin for MSCs defines them as bone marrow-derived stem cells, adipose tissue-derived stem cells, and, among many others, dental stem cells. According to the tissue of origin, DSCs are further stratified into dental pulp stem cells, periodontal ligament stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, and dental papilla cells. There are numerous in vitro/in vivo reports suggesting successful mineralization potential or osteo/odontogenic ability of MSCs. Still, there is further need for the optimization of MSCs-based tissue engineering methods, and the introduction of genes related to osteo/odontogenic differentiation into MSCs might aid in the process. In this review, articles that reported enhanced osteo/odontogenic differentiation with gene introduction into MSCs will be discussed to provide a background for successful bone tissue engineering using MSCs with artificially introduced genes.

Alveolar distraction osteogenesis versus autogenous onlay bone graft for vertical augmentation of severely atrophied alveolar ridges after 12 years of long-term follow-up.

OBJECTIVE: The aim of this study was to evaluate alveolar distraction osteogenesis (ADO) and autogenous onlay bone graft (AOBG) procedures by comparing their long-term results and their ability to correct severe vertical alveolar defects for further rehabilitation. STUDY DESIGN: Fourteen patients treated with ADO and 28 patients treated with AOBG were included in this study. Radiographic measurements of alveolar bone heights over time and the implant survival and success were compared for the 2 groups. RESULTS: The vertical bone gain was 8.4 ± 2.6 mm for ADO and 6.5 ± 2.3 mm for AOBG. After a mean follow-up period of 7.1 years, there was no significant difference between the 2 groups regarding alveolar bone heights over time and implant survival and success (P > .05). The cumulative survival and success rates were 97.3%, 92.7% in the ADO group and 94.1%, 90.2% in the AOBG group, respectively. CONCLUSION: Both ADO and AOBG may be reliable and effective for ridge augmentation procedures of severe vertical alveolar bone defects and subsequent dental rehabilitation using implants.

Self-inflating oral tissue expander for ridge augmentation in the severely atrophic mandible.

In dentistry, tissue expanders have been used to obtain sufficient soft tissue for alveolar bone augmentation in the severely atrophic ridge. Herein, we review two cases of soft tissue augmentation using a self-inflating tissue expander in patients in the Department of Oral and Maxillofacial Surgery at Ewha Womans University Mokdong Hospital for bone graft and implant operations. The results of each patient were presented using pre-operative and post-operative radiographs and clinical exams. The results of our study indicate successful bone graft and implant surgery using a self-inflating tissue expander.

Prospective biomarker evaluation in patients with osteonecrosis of the jaw who received bisphosphonates.

Bone biomarkers have been suggested for the risk assessment for osteonecrosis of the jaw, a serious complication associated with bisphosphonate (BP) use; however, no consensus has been reached. This study investigated the possible associations between bone biomarkers and the development of bisphosphonates-related osteonecrosis of the jaw (BRONJ). This is a case-control study of 37 patients with BRONJ (age, 73.6±11.2years) who had at least 1 sample available at diagnosis, out of which, 35 were taking BPs for osteoporosis and 2 patients for bone metastasis. Age- and gender-matched 37 patients who had been exposed to BPs for >24months and had no evidence of BRONJ after dentoalveolar surgery served as control group. The association between biomarkers (osteocalcin [OC], deoxypyridinoline [DPD], C-terminal telopeptide of collagen I [CTX], N-terminal telopeptides [NTX], bone-specific alkaline phosphatase [BAP], and parathyroid hormone [PTH]) and BRONJ development, the effects of BP discontinuation on biomarkers, and the performance of biomarkers for risk assessment were investigated. In our study, the PTH levels were found to be significantly higher in BRONJ patients compared to controls (P<0.05). But the OC, DPD, CTX, NTX, and BAP levels were not significantly different between the 2 groups (P>0.05). The CTX level in reference to a 150pg/mL cutoff was also not significant for BRONJ development (P>0.05). Among BRONJ patients who discontinued BP, in a linear mixed model, only CTX showed a significant increase over time (ß=0.002, P=0.007). The cutoff PTH level was >41.52pg/mL (AUC=0.719, P=0.009), and that of CTX was ≤0.094ng/mL (AUC=0.619, P=0.069). In conclusion, there is insufficient evidence for the risk prediction for BRONJ of current bone biomarkers; additional research is necessary.

Iatrogenic pneumomediastinum with extensive subcutaneous emphysema after endodontic treatment: report of 2 cases.

Pneumomediastinum with subcutaneous emphysema is a relatively rare complication of dental treatment. The most common dental etiology of this complication is the introduction of air via the air-turbine handpiece during surgical extraction of an impacted tooth, but this complication is very rare after nonsurgical endodontic treatment. We report herein 2 cases of massive pneumomediastinum and cervicofacial subcutaneous emphysema that developed after opening an access cavity for endodontic retreatment. We describe its etiologies and guidelines for the prevention of this complication during nonsurgical endodontic treatment.

Comparison of implant stability after different implant surface treatments in dog bone.

OBJECTIVES: The purpose of this investigation was to evaluate the effects of different implant surface treatments on implant stability in dog mandibles. MATERIAL AND METHODS: A total of 30 implants (Dentium Co, Seoul, Korea) were placed in 5 dog mandibles. Bone quality was assessed at each site. Implant stability was evaluated using 2 different methods. An Osstell resonance frequency analyzer (RFA) was used to determine the stability at baseline (day 1), and 3, 6 and 10 weeks after surgery. Animals were euthanized 10 weeks after implant installation. Specimens were obtained and submitted to the laboratory processing. Sections were stained with hematoxylin and eosin for histologic and histomorphometric analyses. All implantation sites in dog mandibles demonstrated bone types II and III. RESULTS AND CONCLUSIONS: All implants showed good primary stability at baseline in terms of insertion torque. The results of this study suggest that surface treatment may have significant effects on biological stability 3 weeks after implant placement. Further studies are needed to confirm these initial observations in poor quality bone.

Effects of polycaprolactone-tricalcium phosphate, recombinant human bone morphogenetic protein-2 and dog mesenchymal stem cells on bone formation: pilot study in dogs.

PURPOSE: The aim of this study was to evaluate the survival, proliferation, and bone formation of dog mesenchymal stem cells (dMSCs) in the graft material by using Polycaprolactone-tricalcium phosphate (PCL-TCP), auto-fibrin glue (AFG), recombinant human bone morphogenetic protein-2 (rhBMP-2), and dMSCs after a transplantation to the scapula of adult beagle dogs. MATERIALS AND METHODS: The subjects were two beagle dogs. Total dose of rhBMP-2 on each block was 10 microg with 50 microg/mg concentration. The cortical bone of the scapula of the dog was removed which was the same size of PCL-TCP block (Osteopore International Pte, Singapore; 5.0x5.0x8.0 mm in size), and the following graft material then was fixed with orthodontic mini-implant, Dual-top (Titanium alloy, Jeil Co. Seoul, Korea). Four experimental groups were prepared for this study, Group 1: PCL-TCP + aFG; Group 2: PCL-TCP + aFG + dMSCs; Group 3: PCL-TCP + aFG + dMSCs + rhBMP-2; Group 4: PCL-TCP + aFG + dMSCs + rhBMP-2 + PCL membrane. The survival or proliferation of dMSCs cells was identified with an extracted tissue through a fluorescence microscope, H-E staining and Von-Kossa staining in two weeks and four weeks after the transplantation. RESULTS: The survival and proliferation of dMSCs were identified through a fluorescence microscope from both Group 1 and Group 2 in two weeks and four weeks after the transplantation. Histological observation also found that the injected cells were proliferating well in the G2, G3, and G4 scaffolds. CONCLUSION: This study concluded that bone ingrowth occurred in PCL-TCP scaffold which was transplanted with rhBMP-2, and MSCs did not affect bone growth. More sufficient healing time would be needed to recognize effects of dMSCs on bone formation.

Evaluation on the psychosocial status of orthognathic surgery patients.

OBJECTIVE: This study was performed to evaluate the psychosocial status of orthognathic surgery patients through the Minnesota Multiphasic Personality Inventory (MMPI) and the Symptom Checklist 90-Revision (SCL-90-R). STUDY DESIGN: A total of 34 patients were enrolled in the study. They were assessed with the MMPI and the SCL-90-R before surgery and followed-up for 6 months after the operation with the MMPI. Comparisons between the personality characteristics of preoperative and postoperative patients and a total of 30 dental students with class I occlusion were made with the t test. RESULTS: The majority of patients showed no abnormal findings in the MMPI psychologic status. Significant differences in personality characteristics were noticed after orthognathic surgery. CONCLUSIONS: The results of this study suggest that surgical treatment of dentofacial deformities may induce psychologic changes, such as depression, and that the improvement in facial deformities and enhanced sense of esthetic satisfaction may have a positive influence on psychosocial aspects.