Risk factors associated with the development of osteoradionecrosis (ORN) in Head and Neck cancer patients in Ireland: A 10-year retrospective review

BACKGROUND AND PURPOSES

To assess osteoradionecrosis (ORN) incidence in a population of Irish Head and Neck cancer (HNC) patients, and assess precipitating factors that may contribute to ORN development to aid prevention.

MATERIALS AND METHODS

Review of 1050 HNC patients attending the Dental Oncology Clinic, CUDSH between 2010 and 2021 identified 47 cases of ORN. Medical, dental and radiotherapy records of these forty-seven patients were retrospectively reviewed. Patient-, tumour-, and treatment-related variables were investigated in association with osteoradionecrosis development. Analysis conducted using SPSS, Pearson's Chi-square test (p < 0.05), and ordinal regression model.

RESULTS

ORN incidence was 4.4 %. Median time from radiotherapy (RT) to ORN development was 9.5 months (range 1-98.5 months). ORN development within the mandibular surgical site was significant (p <.001), presenting at a higher Notani grade (p =.002), in mid-mandibular body region (p =.028), at radiation doses ≥ 60 Gy (p =.035), due to induced causes (p =.029), and without resolution (p =.019).

CONCLUSION

This is the first retrospective study of ORN in HNC patients in Ireland over 10-year period. ORN incidence was extremely low (4.4%). As patients reported high smoking/alcohol use and poor dental attendance pre-diagnosis, this suggests intensive dental intervention pre/post-diagnosis contributed to low ORN rates. Mandibular surgery pre-RT increased risk of developing ORN at the surgical site. Therefore, we recommend future treatment planning should contour the surgical site, designating it an organ at risk (OAR), assigning a dose constraint, where oncologically possible, with emphasis on reducing the hot-spot to this region; findings reinforce importance of life-long expert dental care to reduce ORN incidence.

Mandibular resection and defect reconstruction guided by a contour registration-based augmented reality system: A preclinical trial

The aim of this study was to verify the feasibility and accuracy of a contour registration-based augmented reality (AR) system in jaw surgery. An AR system was developed to display the interaction between virtual planning and images of the surgical site in real time. Several trials were performed with the guidance of the AR system and the surgical guide. The postoperative cone beam CT (CBCT) data were matched with the preoperatively planned data to evaluate the accuracy of the system by comparing the deviations in distance and angle. All procedures were performed successfully. In nine model trials, distance and angular deviations for the mandible, reconstructed fibula, and fixation screws were 1.62 ± 0.38 mm, 1.86 ± 0.43 mm, 1.67 ± 0.70 mm, and 3.68 ± 0.71°, 5.48 ± 2.06°, 7.50 ± 1.39°, respectively. In twelve animal trials, results of the AR system were compared with the surgical guide. Distance deviations for the bilateral condylar outer poles were 0.93 ± 0.63 mm and 0.81 ± 0.30 mm, respectively (p = 0.68). Distance deviations for the bilateral mandibular posterior angles were 2.01 ± 2.49 mm and 2.89 ± 1.83 mm, respectively (p = 0.50). Distance and angular deviations for the mandible were 1.41 ± 0.61 mm, 1.21 ± 0.18 mm (p = 0.45), and 6.81 ± 2.21°, 6.11 ± 2.93° (p = 0.65), respectively. Distance and angular deviations for the reconstructed tibiofibular bones were 0.88 ± 0.22 mm, 0.84 ± 0.18 mm (p = 0.70), and 6.47 ± 3.03°, 6.90 ± 4.01° (p = 0.84), respectively. This study proposed a contour registration-based AR system to assist surgeons in intuitively observing the surgical plan intraoperatively. The trial results indicated that this system had similar accuracy to the surgical guide.

Injectate spread in ultrasound-guided inferior alveolar nerve block: a cadaveric study

PURPOSE

Ultrasound-guided inferior alveolar nerve block (UGIANB) is a mandibular analgesic procedure in which local anesthetic is injected into the pterygomandibular space (PMS). Several studies have reported the clinical efficacy of UGIANB for mandibular surgeries; however, its effective range has never been investigated. We performed a cadaveric study to investigate the success rate of UGIANB injections and to determine whether injected dye could stain the mandibular nerve (MN) trunk and its branches.

METHODS

We performed UGIANB on the bilateral faces of 4 Thiel-embalmed cadavers. A needle was advanced to the PMS under ultrasound guidance and 5 mL of dye was injected. The cadaver was dissected and inspected for the presence of dye in the PMS; the range of dye spread to any of the inferior alveolar nerve (IAN), lingual nerve (LN), buccal nerve (BN), mandibular nerve (MN), auriculotemporal nerve (ATN), or facial nerves; and for the presence of intravascular dye.

RESULTS

We performed eight UGIANB procedures on four cadavers. Dye was observed in the PMS in 7/8 injections. Staining was observed in all IAN, LN, and BNs that could be identified at dissection. No MN or auriculotemporal nerves (ATNs) were stained in any injections. No intravascular dye was observed in any injections.

CONCLUSIONS

UGIANB can administer anesthetic into the PMS with high accuracy. UGIANB injections reached the IAN, LN, and BNs, but did not reach the MN or ATNs located outside the PMS. The findings of this cadaveric study indicate that UGIANB can provide sufficient analgesia for mandibular surgeries.

Utilization of a 3D printed dental splint for registration during electromagnetically navigated mandibular surgery

PURPOSE

A dental splint was developed for non-invasive rigid point-based registration in electromagnetically (EM) navigated mandibular surgery. Navigational accuracies of the dental splint were compared with the common approach, that is, using screws as landmarks.

METHODS

A dental splint that includes reference registration notches was 3D printed. Different sets of three points were used for rigid point-based registration on a mandibular phantom: notches on the dental splint only, screws on the mandible, contralateral screws (the side of the mandible where the sensor is not fixated) and a combination of screws on the mandible and notches on the dental splint. The accuracy of each registration method was calculated using 45 notches at one side of the mandible and expressed as the target registration error (TRE).

RESULTS

Average TREs of 0.83 mm (range 0.7-1.39 mm), 1.28 mm (1.03-1.7 mm), 2.62 mm (1.91-4.0 mm), and 1.34 mm (1.30-1.39 mm) were found, respectively, for point-based registration based on the splint only, screws on the mandible, screws on the contralateral side only, and screws combined with the splint.

CONCLUSION

For dentate patients, rigid point-based registration performs best utilizing a dental splint with notches. The dental splint is easy to implement in the surgical, and navigational, workflow, and the notches can be pinpointed and designated on the CT scan with high accuracy. For edentate patients, screws can be used for rigid point-based registration. However, a new design of the screws is recommended to improve the accuracy of designation on the CT scan.

Correction of mandibular deviation and maxillary occlusal canting with mandibular "early" surgery and microscrews: Two case reports

Facial asymmetry is a common complaint in patients with facial concerns. Some patients have mandibular asymmetries that have light maxillary cant compensation due to a reduced gingival exposure. A common treatment in facial asymmetries is bimaxillary surgery treatment. However, there are no cases of non-severe occlusal plane canting (OPC) with mandibular asymmetry treated with mandibular surgery and miniscrews for the extrusion of the maxillary molars. The aim of this article is to show how to correct mandibular asymmetries combined with OPC by making a single mandibular "early surgery" combined with the extrusion of the maxilla with miniscrews to correct the occlusal plane in order to avoid a Le Fort I surgery. This type of treatment provides lower medical costs, shorter surgeries, and less postoperative discomfort and invasion for patients.

Use of 3-D printing technologies in craniomaxillofacial surgery: a review

Three-dimensional (3-D) printing is a method of manufacturing in which materials like plastic or metal are deposited onto one another in layers to produce a 3-D object. Because of the complex anatomy of craniomaxillofacial structures, full recovery of craniomaxillofacial tissues from trauma, surgeries, or congenital malformations is extremely challenging. 3-D printing of scaffolds, tissue analogs, and organs has been proposed as an exciting alternative to address some of these key challenges in craniomaxillofacial surgery. There are four broad types of 3-D printing surgical applications that can be used in craniomaxillofacial surgery: contour models (positive-space models to allow preapplication of hardware before surgery), guides (negative-space models of actual patient data to guide cutting and drilling), splints (negative-space models of virtual postoperative positions to guide final alignment), and implants (negative-space 3-D printed implantable materials or 3-D printed molds into which nonprintable materials are poured). 3-D printing technology is being successfully used for surgeries for head and neck malignancies, mandibular reconstruction, orthognathic surgeries, for mandibulectomies after osteoradionecrosis, orbital floor fracture surgeries, nasal reconstruction, and cranioplasties. The excitement behind 3-D printing continues to increase and hopefully will drive improvements in the technology and its surgical applications, especially in craniomaxillofacial region. This present review sets out to explore use of 3-D printing technologies in craniomaxillofacial surgery.

Perioral soft tissue change after isolated mandibular surgery for asymmetry patients

INTRODUCTION

This study was intended to determine whether isolated mandibular surgery for the correction of asymmetry could also change perioral soft tissue asymmetry.

PATIENTS AND METHODS

Skeletal class III patients who had undergone mandibular set-back surgery were included. The subjects were composed of two groups with (n = 20) or without (n = 30) menton (Me) deviation over 4 mm. The perioral lip landmarks were analyzed on three-dimensional image from cone-beam computed tomography taken before and 6 months after the operation. The bilateral and inter-group differences and pre- and post-operative changes were statistically analyzed.

RESULTS

The corner of mouth on the deviated side was 1.9 mm shorter vertically than that on the contralateral side in patients with asymmetry. After mandibular surgery, the deviated Me moved 5.5 mm to the contralateral side and the lip canting was corrected by 2.4° in the asymmetry group. The degree of Me deviation was significantly correlated with the degree of midline asymmetry in perioral soft tissue landmarks including subnasale, upper and lower lip midline. The predictor variable that affected the changes in lip cant was the surgical correction of Me deviation.

DISCUSSION

The correction of chin deviation by isolated mandibular surgery could significantly improve the subnasal and lip asymmetry.

Impact of different sedation protocols and perioperative procedures on patients admitted to the intensive care unit after maxillofacial tumor surgery of the lower jaw: A retrospective study

Maxillofacial tumor surgery often necessitates prolonged invasive ventilation to prevent blockage of the respiratory tract. To tolerate ventilation, continuously administered sedatives are recommended. Half-time of sedative or analgesic medication is an important characteristic by which narcotic drugs are chosen, due to the fact that weaning period increases with half-time. The aim of our study was to investigate whether a change in sedation regimen would affect the length of invasive ventilation or intensive care unit stay and medical costs. Additionally, the impact of various surgical procedures was analyzed. Data of 157 patients after mandibular surgery were retrospectively analyzed over 5 years in count regression models. Of those patients, 84 received a sedation regimen with sufentanil and midazolam and 73 with remifentanil and propofol. The impact of the surgical procedures (tracheostomy, tumor resection, neck dissection and length of operation) and the patient age and sex were analyzed with respect to length of ventilation and ICU days. Cost savings were calculated. Our data show that patients receiving remifentanil/propofol had fewer ventilation days (2.5 ± 2.5 versus 6.1 ± 4.6 days, P < 0.001) and were discharged earlier from the intensive care unit than patients receiving sufentanil/midazolam (5.1 ± 3.8 versus 9.2 ± 6.2 days, P < 0.001), leading to calculated cost savings of about 8000 Euro per patient. Length of operation negatively influenced length of ICU stay (P < 0.001). In conclusion, short-acting drugs such as remifentanil/propofol, as well as tracheostoma and shortened surgery duration may reduce the postoperative need for invasive ventilation and length of intensive care unit stay.

The "Rubber Band" and "Slingshot" Effects of the Posterior Airway Space in Mandibular Orthognathic Surgeries

INTRODUCTION

Mandibular surgeries are the most common orthognathic procedures that are undertaken. The pharyngeal airway space (PAS) is influenced by the changes in the sagittal changes of the mandible. Mandibular advancement surgeries are used to an advantage in obstructive sleep apnea cases to improve the airway space. On the contrary, there can be a considerable decrease in the airway space during mandibular setback procedures. Numerous studies have been conducted to study the effect of changes in the PAS during mandibular procedures. However, a combined radiographic and endoscopic analysis of the airway space has been sparsely done in recent literature.

MATERIALS AND METHODS

Thirty-one patients with mandibular discrepancies who needed mandibular surgeries were chosen. The assessment of PAS was done using both lateral cephalograms and endoscopic examination.

RESULTS

As lateral cephalograms can study only the two-dimensional changes in the PAS, endoscopic examination both pre operatively and post operatively enabled the exact assessment of mandibular surgeries on the PAS. The PAS responds to setback mandibular surgery by modifying itself- called the "Rubber band" effect and in advancement surgeries as "Slingshot effect".