Inferior Alveolar Nerve Injury in Trauma-Induced Mandible Fractures.

PURPOSE: This prospective observational cohort study sought to determine the prevalence of inferior alveolar nerve (IAN) injury after mandibular fractures before and after treatment and to elucidate factors associated with the incidence of post-treatment IAN injury and time to normalization of sensation. MATERIALS AND METHODS: Consenting patients with mandibular fractures (excluding dentoalveolar, pathologic, previous fractures, or mandibular surgery) were prospectively evaluated for subjective neurosensory disturbance (NSD) and underwent neurosensory testing before treatment and then 1 week, 1.5, 3, 6, and 12 months after treatment. RESULTS: Eighty patients (men, 83.8%; mean age, 30.0 yr; standard deviation, 12.6 yr) with 123 mandibular sides (43 bilateral) were studied. Injury etiology included assault (33.8%), falls (31.3%), motor vehicle accidents (25.0%), and sports injuries (6.3%). Half the fractures (49.6%) involved the IAN-bearing posterior mandible; all condylar fractures (13.0%) had no NSD. Treatment included open reduction and internal fixation (ORIF; 74.8%), closed reduction and fixation (22.0%), or no treatment (3.3%). Overall prevalence of IAN injury was 33.7% (95% confidence interval [CI], 24.8-42.6) before treatment and 53.8% (95% CI, 46.0-61.6) after treatment. In the IAN-bearing mandible, the prevalence was 56.2% (95% CI, 43.2-69.2) before treatment and 72.9% (95% CI, 63.0-82.7) after treatment. In contrast, this prevalence in the non-IAN-bearing mandible was 12.6% (95% CI, 4.1-21.1) before treatment and 31.6% (95% CI, 20.0-43.3) after treatment. Factors associated with the development of post-treatment IAN injury included fracture site and gap distance (a 1-mm increase was associated with a 27% increase in odds of post-treatment sensory alteration). Time to normalization after treatment was associated with type of treatment (ORIF inhibited normalization) and fracture site (IAN-bearing sites took longer to normalize). CONCLUSION: IAN injury was 4 times more likely in IAN-bearing posterior mandibular fractures (56.2%) than in non-IAN-bearing anterior mandibular fractures (12.6%). After treatment, IAN injury prevalence (in 12 months) was higher (72.9% in posterior mandible, 31.6% in anterior mandible).

Effect of postoperative radiation therapy on mandibular reconstruction using a modular endoprosthesis - a pilot study.

The endoprosthetic system has been shown to be a potential option for mandibular reconstruction. The objective of this pilot in vivo animal study was to determine the effects of postoperative radiation using brachytherapy on bone and soft tissue healing in mandibles reconstructed with the endoprosthesis. Six adult Macaca fascicularis mandibles were reconstructed with a cemented endoprosthesis after segmental body resection. The animals were divided into two groups. The test group was subjected to radiation therapy 1 month postoperation while the control group did not receive any radiation. Results showed no major radiation side effects. Mucosal ulcerations and wound dehiscence at the radiated sites healed within 4 weeks. One animal from each group had prosthesis failure and was unable to complete the study. Micro-CT findings indicated no significant differences between the total bone volume percentage (TBV%) of the study and control groups. Histomorphometrical analysis using grading scales also showed no significant differences between the two groups. Under the study conditions, postoperative brachytherapy did not affect the tissue response around the endoprosthesis within the early 6 months postradiation period. The endoprosthesis, therefore, remains a viable reconstructive option when postoperative radiation is prescribed.

Biocompatibility and bone formation with porous modified PMMA in normal and irradiated mandibular tissue.

UNLABELLED: A cemented mandibular endoprosthesis is a potentially viable option for mandibular reconstruction after ablative surgery. The commonly used PMMA cement has the inherent weakness of a lack of bioactivity. Improvement by the addition of porosities and bioactive compounds like calcium phosphates may resolve this issue. OBJECTIVE: The objective of this study was to assess the bone and tissue response to two modified PMMA cements with post-operative radiation as an additional influencing factor. MATERIALS & METHODS: An in vivo animal study was performed using a mandibular rabbit model. A porous PMMA cement (A) and a porous cement incorporated with Beta-tricalcium phosphate particles (b-TCP) (B) were placed in bilateral mandibular defects with exposed roots and mandibular nerve of 20 animals. Half of the animals underwent additional post-operative radiation. RESULTS: The animals were healthy with only a minor complication in one rabbit. Temperature analysis showed no significant risk of thermal necrosis with the maximal in vivo cement temperature at 37.8°C. Histology demonstrated: (1) good bone ingrowth around the defect as well as within the pores of the cement and defect bridging was achieved in 70% of the specimens after 12-15 weeks of implantation, (2) no pulpal injury with minor secondary cementum response, (3) an intact mandibular nerve with no inflammation, (4) extensive degradation and resorption of the b-TCP particles by 12-15 weeks, and (5) presence of an intervening thin fibrous tissue at the bone-to-cement interface. Histomorphometrical analysis revealed that there was no difference between the different cements and the presence or absence of post-operative radiation. The 12-15 weeks specimens showed significantly more bone ingrowth and bone maturity than the 4-7 weeks specimens. CONCLUSION: Both modified PMMA cements have good biocompatibility, bioactivity and support bone ingrowth and additional post-operative radiation did not show any negative effects.

Bone cements and their potential use in a mandibular endoprosthesis.

Bone cement was first used in the 1950s. Since then many modifications have been made and alternatives developed to the original polymethylmethacrylate (PMMA) cement. In view of the use of bone cement in a novel mandibular endoprosthetic system, we performed a review of the current literature on this material. Different cements are described and their potential use in a mandibular endoprosthetic system discussed. The PMMA-based cements are currently the most suitable choice. Plain PMMA has the longest track record and is the default choice for the initial development phase of this system. If there is a significant risk of infection, then an antibiotic-loaded PMMA cement can be selected. However, modified PMMA cements, composite resin cements, osteoinductive calcium phosphate compounds, and cementless fixation are options that offer advantages over PMMA cements, and further research should be conducted to study their suitability.

Effect of orthognathic surgery on the posterior airway space (PAS).

Orthognathic surgery has been used regularly to treat dentofacial deformities. The surgical procedures affect both the facial appearance as well as the posterior airway space (PAS). Our current literature indicates that setback procedures produce an inferior repositioning of the hyoid bone and posterior displacement of the tongue and the soft palate. These movements cause anteroposterior and lateral narrowing of the PAS. Most authors agree that these effects are permanent. The PAS changes in turn produce an adaptive posturing, with an increased craniocervical angle to open up the PAS. Even though most patients do not display snoring and obstructive sleep apnoea (OSA) post-surgery, there is certainly an increased possibility in patients with already compromised airways. Therefore, patients who are undergoing orthognathic surgery should be screened for excessive daytime somnolence, snoring, increased body mass index (BMI) and medical conditions related to OSA and sent for an overnight polysomnography (PSG) if OSA is suspected. Then the proposed treatment plan may be modified according to the risk of potential airway compromise or even to improve it. Conversely, advancement of the maxilla and mandible causes widening of the airway in both the anteroposterior and lateral dimensions. This effect would translate to better airflow and decreased airway resistance. This is supported by the evidence showing high success rates when orthognathic surgery, especially maxillomandibular advancement (MMA), is utilised to treat OSA.

The use of demineralized bone matrix for grafting during Le Fort I and chin osteotomies: techniques and complications.

PURPOSE: To examine the use of demineralized bone matrix (DBM) in maxillary and chin orthognathic surgery. The use of DBM in orthognathic surgery has not been reported in the literature. PATIENTS AND METHODS: A retrospective review of the orthognathic surgeries performed in 1 university was conducted. Medical records were assessed to determine the materials used, complications, and details of re-operations required. RESULTS: There were 113 suitable patients identified. The DBM group (88 patients) consisted of 61 Le Fort I osteotomies and 46 genioplasties; the non-DBM group (25 patients) consisted of 25 Le Fort I osteotomies and 4 genioplasties. The mean follow-up period was 5.9 months for the DBM group and 6 months for the non-DBM group. There was only 1 technique of applying DBM to genioplasties, but a variety of different graft material combinations was used in the Le Fort I osteotomies. The only significant Le Fort I complication was maxillary sinusitis; its incidence was 3.3% (2 out of 61) for the DBM group, versus 8% (2 out of 25) in the non-DBM group. All the genioplasties had no complications. There were 4 cases of Le Fort I osteotomies which were re-entered (2 cases for suspected infection and 2 cases for re-osteotomies due to occlusal malalignment) and they showed good bony healing. CONCLUSION: The use of DBM does not significantly increase complications and is suitable to be used in both the maxilla and chin during orthognathic surgery.

Predictability of prebent advancement plates for use in maxillomandibular advancement surgery.

PURPOSE: The purpose of this study was to determine the predictability when using prebent advancement (PBA) plates in the maxillary osteotomies of maxillomandibular advancement (MMA) surgery. MATERIALS AND METHODS: A retrospective review of the MMA surgeries at University of Alabama at Birmingham was carried out. Thirty-six obstructive sleep apnea patients who underwent MMA with PBA were included in this study. All cases had fixation of the maxillary osteotomies with KLS Martin PBA titanium plates and screws (KLS Martin, Jacksonville, FL). Lateral cephalometric radiographs were taken within 1 month before surgery (T1), and between 2 to 4 weeks postsurgically (T2). All cephalometric radiographs were analyzed using Planmeca Dimaxis Imaging Software (Helsinki, Finland). Vertical and horizontal measurements were made to several skeletal landmarks including Sella (S), A point (APT), and upper incisor (UPI). The amount of advancement was measured through pre- and postoperative lateral cephalographs and compared with the magnitude of the advancement plates used. RESULTS: All data of 36 patients were included and used for statistics. The data showed that the mean difference was 0.74 mm (advancement is more than the size of the PBA plates) and the mean percentage difference was 11.35%. Fifty percent of the cases had the magnitude of advancement within 1 mm of the PBA size. The predictive analysis found that the PBA size was a significant predictor for the advancement achieved (P < .0001) but not the absolute difference between the advancement achieved and the plate size (P = .0726) and the relative advancement difference (P = .0612). The absolute difference and the relative difference take into account the size of the PBA and are better parameters to judge the predictability of the advancement achieved. The rationale for this unpredictability is largely due to the anatomy of the maxilla and pyriform rims and the adaptation of the PBA to the maxilla. CONCLUSION: There are distinct advantages to the use of PBA plates. The PBA plates have been proven to significantly affect the advancement. However, when very precise movements are required, the size of the PBA used does not predictably correlate to and frequently underestimates the amount of advancement achieved. Therefore accurate model surgeries are still required for most cases.

Quality of life evaluation of maxillomandibular advancement surgery for treatment of obstructive sleep apnea.

PURPOSE: The purpose of this study was to investigate the quality of life (QOL) for patients who underwent maxillomandibular advancement (MMA) surgery for obstructive sleep apnea (OSA) treatment using the Functional Outcomes of Sleep Questionnaire (FOSQ). Correlation of the findings with parameters from the polysomnograph (PSG) and physical examination were also performed. No QOL studies have been carried out for MMA in OSA, and the FOSQ is the most appropriate method. PATIENTS AND METHODS: The FOSQ instrument is a survey designed to evaluate QOL in OSA and proven to be effective. All patients followed a standard prospective protocol of pre- and 6 months postoperative data collection. Clinical radiographs, PSG, FOSQ, endoscopy, and computed tomography scans were analyzed. RESULTS: Fifteen patients with complete data were included in the study. There was minimal change in the BMI from a preoperation mean of 32.10 to 31.50 at 6 months postoperation. The operation was 86.7% (13 of 15) successful (postoperative apnea and hypopnea index [AHI] decreased by 50% and was <20), with a significant decrease of the mean preoperation apnea-hypopnea index (AHI) of 69.12 to 13.87 postoperation (P < .0001). The minimum oxygen saturation (Lsat) correspondingly increased from a mean of 76.49 to 84.96 (P = .0001). A total of 93.3% of our patients achieved a successful QOL change based on a FOSQ score of greater than or equal to 18. There was statistically significant changes in all domains; general productivity (P = .0003), social outcome (P = .0020), activity level (P = .0008), vigilance (P = .0028), intimacy and sex (P = .0039), and the total score (P = .0002) postoperatively. Changes of Lsat and AHI were highly correlated (r = -0.728, P = .002). The magnitude of the Le Fort advancement was also found to be negatively correlated to the change in AHI (r = -0.544, P =.036). There was no correlation between the FOSQ scores and all other parameters, including both the PSG parameters (AHI and Lsat). CONCLUSION: MMA remains the most effective operation for the treatment of OSA and yet no QOL studies have been carried out. The disease-specific QOL instrument (FOSQ) showed the subjective functional improvement in MMA patients. QOL instruments should be used for all surgical based treatment as they add a new dimension to the assessment of the patient and procedures.

Keratoprosthesis surgery for end-stage corneal blindness in asian eyes.

PURPOSE: To establish a multidisciplinary surgical program for osteo-odonto-keratoprosthesis (OOKP) surgery in Asia and to evaluate efficacy and preliminary safety of this keratoprosthesis in end-stage corneal and ocular surface disease. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Sixteen adults of Asian ethnic origin, bilaterally blind with end-stage corneal blindness from Stevens-Johnson syndrome, or severe chemical or thermal burns. METHODS: Osteo-odonto-keratoprosthesis surgery involves 2 procedures-in stage 1, an autologous canine tooth is removed, modified to receive an optical polymethyl methacrylate cylinder, and implanted into the cheek. The ocular surface is denuded and replaced with full-thickness buccal mucosa. Stage 2 surgery, performed 2 to 4 months later, involves retrieval of the tooth-cylinder complex and implanting it into the cornea, after reflection of the buccal mucosal flap, corneal trephination, iris and lens removal, and anterior vitrectomy. Concurrent glaucoma and vitreoretinal procedures are also performed at either stage, as required. MAIN OUTCOME MEASURES: Visual acuity (VA), field of vision, anatomical integrity and stability, and ocular and oral complications related or unrelated to the OOKP device. RESULTS: Osteo-odonto-keratoprosthesis surgery was performed on 15 patients, with a mean follow-up of 19.1 months (range, 5-31). Intraoperative complications included expulsive hemorrhage (keratoprosthesis device not implanted), tooth fracture (n = 1), oronasal fistula (n = 1), and mild inferior optic tilt (n = 1). Anatomical stability and keratoprosthesis retention has been maintained in all eyes, with no dislocation, extrusion, retroprosthetic membrane formation, or keratoprosthesis-related infection. Other complications not directly related to device insertion included retinal detachment (RD) related to silicone oil removal (n = 1) and endophthalmitis related to endoscopic cyclophotocoagulation performed 1 year after OOKP surgery (n = 1). Eleven patients (73.3%) attained a stable best spectacle-corrected VA of at least 20/40 or better, whereas 9 (60%) attained stable 20/20 vision. Four patients achieved their best visual potential, ranging from 20/100 to counting fingers vision, related to preexisting glaucomatous optic neuropathy or previous RD. CONCLUSIONS: Establishment of our OOKP program suggests that OOKP surgery has the potential to restore good vision to the most severe cases of corneal blindness in an Asian setting, with minimal device-related complications. Longer follow-up of these cases is currently underway.

Bisphosphonate-related osteonecrosis of the jaws.

The purpose of this paper is to highlight an emerging phenomenon of osteonecrosis of the jaws that occurs in some patients who are on long-term bisphosphonate therapy. The condition can appear spontaneously or as a result of trauma, and is difficult to treat. Dental surgeons must be aware of patients who are at risk and institute appropriate preventive care. It is also important to recognize the condition when it does appear and refer appropriately. We present the first local case series of the condition showing varied clinical presentations and treatments.