Posterior maxillary anatomy: implications for Le Fort I osteotomy

Anatomical Factors of the Anterior and Posterior Maxilla Affecting Immediate Implant Placement Based on Cone Beam Computed Tomography Analysis: A Narrative Review

BACKGROUND

The aim of this narrative review was to provide insights into the influence of the morphological characteristics of the anatomical structures of the upper jaw based on cone beam computed tomography (CBCT) analysis on the immediate implant placement in this region.

MATERIAL AND METHODS

To conduct this research, we used many electronic databases, and the resulting papers were chosen and analyzed. From the clinical point of view, the region of the anterior maxilla is specific and can be difficult for immediate implant placement.

FINDINGS

Anatomical structures in the anterior maxilla, such as the nasopalatine canal and accessory canals, may limit and influence the implant therapy outcome. In addition to the aforementioned region, immediate implant placement in the posterior maxilla may be challenging for clinicians, especially in prosthetic-driven immediate implant placement procedures. Data presented within the recently published materials summarize the investigations performed in order to achieve more reliable indicators that may make more accurate decisions for clinicians.

CONCLUSION

The possibility for immediate implant placement may be affected by the NPC shape in the anterior maxilla, while the presence of ACs may increase the incidence of immediate implant placement complications. The variations in IRS characteristics may be considered important criteria for choosing the implant properties required for successful immediate implant placement.

Anatomical factors of the maxillary tuberosity that influence molar distalization

Objective

To examine the areas of the maxillary tuberosity (MT) (coronal, apical, width, and height) with respect to the presence or absence of the third molar to establish possible anatomical limitations for molar distalization.

Methods

A total of 277 tuberosities were evaluated through sagittal computed tomography (CT) images, divided for measurement into coronal (free of bone), apical (area of influence of the maxillary sinus), and tuberosity (bony area) zones, and stratified by the presence or absence of the third molar, sex, and two age subgroups. Mann-Whitney U test was used to compare the groups considering the third molar.

Results

The medians of the width and height of the tuberosity decreased significantly in the absence of the third molar (P < 0.001). The apical area also showed differences, with negative values in the absence of the third molar and positive values in the presence of the third molar (P < 0.001). However, no differences were observed for the coronal area (P > 0.05).

Conclusions

In the absence of the third molar, the size of the MT, represented by its width and height, was smaller and negative values (decrease) were observed for the maxillary sinus. The sagittal CT provides useful information regarding the amount of bone tissue available for distalization and relationship of the second molar with respect to the maxillary sinus, which allows individualizing each case in relation to the amount and type of movement expected.

Le fort I osteotomy with or without concomitant removal of upper third molars: A prospective cohort study of intraoperative findings, related complications, and level of pterygomaxillary separation after down-fracture

The main objective of our study was to assess the clinical implications of concomitant intraoperative removal of maxillary third molars (M3M) with the Le Fort I osteotomy 'twist' technique (LF1twist). A prospective comparative study was carried out regarding the necessity of bone trimming around the pedicle, intra- and postoperative complications, surgery time, and the level of pterygomaxillary junction (PMJ) separation following LF1twist with concomitant intraoperative removal of M3M (test group) versus LF1twist alone (control group). Outcome parameters were assessed from clinical and radiographic measurements. In total, 100 surgery sites were included (50 in each group). The mean surgery time was 53.4 ± 7.8 min, with nonsignificant differences between groups. The frequency of intraoperative complications was negligible, with no significant differences between groups - though all bleeding events (n = 4) occurred when M3M was not removed concomitantly. No postoperative complications were recorded. Percentages of disarticulations occurring at the PMJ were similar in both groups. In conclusion, the results demonstrate that removal of M3M in conjunction with LF1twist does not imply additional surgery time, or differences regarding the level of PMJ separation or perioperative complications. Furthermore, the concomitant procedure reduces the amount of maxillary and palatal bone in the disjunction area, which facilitates down-fracture and field clearing for maxillary repositioning.

Anatomical Variations of the Greater Palatine Foramen in Different Facial Skeletal Relationships and its Implications on LeFort 1 Osteotomy (Trimble's Modification)

Purpose

To determine the positional variations of the greater palatine foramen in different facial skeletal relationships and discuss its surgical implications on the Trimble's modification of Lefort I osteotomy.

Materials and Methods

This retrospective study examined 50 computed tomography scans of patients a total of 100 sides. The sample was divided into four groups: Class 1, Class 2, Class 3 malocclusion and Unilateral cleft lip and palate). The outcome variables included the distance between anterior, middle and posterior points of the GPF to the distal of second molar and variables to assess relative position of the GPF to the posterior maxilla. Outcome measures were to demonstrate intra- and intergroup variability.

Results

Fifty patients (100 sides) were divided into four groups. This included 23 males and 27 females with a mean age of 24.1 years. Significant intergroup variability was observed between all the parameters that demonstrate the relative position of the GPF to (i) the maxillary second molar and (ii) the posterior maxilla. The analysis revealed that the GPF was positioned significantly anterior in Class 2 patients when compared with Class 3 patients.

Conclusion

The GPF exhibits significant positional variability in different facial skeletal relationships which should be borne in mind while designing and performing the Trimble's modification of the Lefort 1 osteotomy.

Anatomy of the greater palatine foramen and canal and their clinical significance in relation to the greater palatine artery: a systematic review and meta-analysis

PURPOSE

Accurate knowledge of greater palatine foramen (GPF) and greater palatine canal (GPC) anatomy is necessary to avoid injury to the greater palatine artery (GPA) when performing a variety of anesthesiologic, dental or surgical procedures. The aim of this paper was to perform a systematic review and meta-analysis of literature on the anatomy and localization of bony structures associated with the GPA, namely the GPF and GPC.

METHODS

A systematic literature search was performed using PubMed, Embase, ScienceDirect, and Web of Science databases. Seventy-five studies were included in the meta-analysis (n = 22,202 subjects).

RESULTS

The meta-analysis showed that the GPF is positioned 17.21 mm (95% CI = 16.34-18.09 mm) from the posterior nasal spine, 2.56 mm (95% CI = 1.90-3.22 mm) from the posterior border of the hard palate, 46.24 mm (95% CI = 44.30-48.18 mm) from the anterior nasal spine, 15.22 mm (95% CI = 15.00-15.43 mm) from the midline maxillary suture, 37.32 mm (95% CI = 36.19-38.45 mm) from the incisive foramen, and opposite the third maxillary molar (M3) in 64.9% (58.7-70.7%) of the total population.

CONCLUSION

An up-to-date, comprehensive analysis of GPF and GPC clinical anatomy is presented. The results from this evidence-based anatomical study provides a unified set of data to aid clinicians in their practice.

Radiological Analysis of Maxillary Artery Relationships to Key Bony Landmarks in Maxillofacial Surgery

The maxillary artery (MA) is a key structure at risk of injury in numerous oral and maxillofacial surgical (OMS) procedures. Knowledge of safe distances from this vessel to surgically familiar bony landmarks could improve patient safety and prevent catastrophic haemorrhage. Distances between the MA and bony landmarks on the maxilla and mandible were measured using CT angiograms on 100 patients (200 facial halves). The vertical height of the pterygomaxillary junction (PMJ) was mean (SD) measurement of 16 (3) mm. The MA enters the pterygomaxillary fissure (PMF) a mean (SD) distance of 29 (3) mm from the most inferior point of the PMJ. The mean (SD) shortest distance between the MA and medial surface of the mandible was 2 (2) mm (with the vessel directly contacting the mandible in 17% of cases). The branchpoint (bifurcation of the superficial temporal artery (STA) and MA) was directly in contact with the mandible in 5% of cases. The mean (SD) distances between this bifurcation point and the medial pole of the condyle were 20 (5) mm and 22 (5) mm, respectively. A horizontal plane through the sigmoid notch perpendicular to the posterior border of the mandible is a good approximation of the trajectory of the MA. The branchpoint is usually within 5 mm of this line and inferior in 70% of cases. Surgeons should take note that both the branchpoint and the MA contact the surface of the mandible in a significant number of cases.

Linear and angular measurement using cone-beam computed tomography to enhance safety in Le Fort I osteotomy with tuberosity cut

OBJECTIVE

The study aimed to evaluate surgical angles for tuberosity cut and linear and angular measurements for all horizontal cuts in Le Fort I osteotomy using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This study included 189 CBCT scans to assess the surgical angles on 3 different sites distal to maxillary second molars relative to the midsagittal plane (MSP) and the buccal cortical plane (BCP) in relation to the descending palatine foramen for tuberosity cut. The linear and angular measurements for all horizontal cuts in Le Fort I osteotomy were also evaluated.

RESULTS

The mean surgical angles for tuberosity cut varied from 58.90 to 95.28° and 74.85 to 100.93° according to the MSP and the BCP, respectively. For the horizontal cuts, mean lengths (angles) for posterior buccal and lateral nasal wall osteotomies were 27.44 mm (13.62°) and 33.20 mm (9.60°), respectively, and a mean length of 47.12 mm was measured for nasal septum osteotomy. Additionally, the presence of impacted third molar resulted in significantly higher mean surgical angles than those with fully erupted or without third molars (p < 0.01).

CONCLUSIONS

Overall, angles running through the buccal midpoint of the third molars relative to the MSP (76.56°) or the BCP (92.31°) might be the most appropriate in clinical practice. Furthermore, some caution seems warranted when performing tuberosity cuts with the impacted third molars.

CLINICAL RELEVANCE

To avoid potential damage to the descending palatine artery for tuberosity cut in Le Fort I osteotomy.

Aberrations in Maxillary Anatomy of Adult Patients with Cleft Maxillary Hypoplasia: A Computed Tomographic Study

Aim

The aim of this study was to evaluate the maxillary anatomy in patients with cleft maxillary hypoplasia using computed tomogram.

Materials and Methods

A cross-sectional observational study was carried out in all cleft patients reporting to our department for the correction of secondary cleft deformities. A preoperative computed tomogram of the midface (from the superior orbital rim to the maxillary occlusal plane) was recorded to assess the parameters which evaluate the maxillary and pterygomaxillary anatomy in cleft maxillary hypoplasia patients.

Results

A total of 18 adult patients (female-5; male-13) were included in the study, which includes 15 unilateral and 3 bilateral cleft lip and palate patients. All the patients had undergone palatoplasty in their early childhood. Evaluation of the circum maxillary and pterygo-maxillary anatomy on the computed tomogram revealed that the average width of maxillary tuberosity was (mean-6.91 mm on cleft side, 4.51 mm on noncleft side); distance between medial and lateral pterygoid plates was (mean-6.45 mm on cleft side, 5.94 mm on noncleft side); distance from greater palatine foramen to posterior palatal border was (mean-5.6 mm on cleft side, 6.1 mm on noncleft side); distance from greater palatine foramen to pterygoid process was (mean-4.83 mm on cleft side, 5.6 mm on noncleft side); distance from pyriform rim to greater palatine foramen was (mean-30.0 mm on cleft side, 31.8 mm on noncleft side); inter pterygoid distance between medial pterygoid plates at the level of pterygoidhamulus was (mean-3.3 cms = 33 mm); inter pterygoid distance between medial pterygoid plates at skull base was (mean-3.0 = 30 mm).

Conclusion

Maxillary hypoplasia in adult cleft patients distorts the circum maxillary and pterygomaxillary anatomy with cleft side being more hypoplastic compared to the noncleft side which needs to be evaluated prior to planning maxillary advancement.

The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong: History and description of cranial and postcranial skeletal remains

OBJECTIVES

The present work describes the status and contents of The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong.

MATERIALS AND METHODS

The Collection originates from the 1980s and became officially established in 2017 for teaching and research purposes. Most of the Collection consists of unclaimed human remains of southern Chinese individuals exhumed from local cemeteries and donated to the Faculty in the last few decades. The demographic information was provided largely from burial records and forensic estimations. Since 2016, the Collection has undergone a process of reorganization into cranial and postcranial remains, followed by preservation procedures that included cleaning and classification.

RESULTS

The Collection currently consists of remains belonging to about 368 individuals (243 males, 54 females, 71 unknown), with ages ranging from 0.8 to 90 years (mean 57.4 years). It comprises cranial remains belonging to 260 individuals (169 males, 39 females, 52 unknown), and postcranial remains belonging to 248 individuals (180 males, 42 females, 26 unknown). The preservation status ranges from poor to good, with the cranial remains better preserved than the postcranial elements. For a large number of individuals, ear ossicles, soil samples, and other materials are also available.

DISCUSSION

The Collection is accessible to local and international institutions for teaching and research.

Evaluation of Lefort I Osteotomy Line and Pterygomaxillary Junction Region in Patients With Cleft Lip and Palate

OBJECTIVE

This study aimed to evaluate the Le Fort I osteotomy line and pterygomaxillary junction via cone-beam computed tomography in individuals with cleft lip and palate (CLP).

DESIGN

Retrospective study. Patients and Methods: The study included individuals older than 16 years with CLP, who were scheduled for repositioning of the maxilla by Le Fort I osteotomy, and those with class III malocclusion with maxillary hypoplasia, who were scheduled for Le Fort I osteotomy. The measurements made in the area of the cleft of individuals with CLP were compared with both the side with no cleft and those with class III malocclusion with maxillary hypoplasia. A total of 11 measurements were made on the axial section parallel to the Frankfurt Horizontal plane, corresponding to the lower 1/5 of the distance between the infraorbital foramen and the anterior nasal spine.

RESULTS

There were significant differences both in the comparisons made between the individuals with CLP and those without CLP in terms of the canal-anterior alveolar crest (G) and sinus-anterior alveolar crest (L) measurements (P < .05). The mean measurement values showed that the measurement results were higher in individuals with CLP in general.

CONCLUSION

In conclusion, we believe that there might be difficulties both in osteotomy and down fracture stages during Le Fort I osteotomies performed in individuals with CLP.

CBCT study on the positional relationship between marginal points of pterygomaxillary junction and anterior nasal spine

PURPOSE

This study aimed to locate the inferior end (Pti) and the superior end (Pts) of pterygomaxillary junction (PMJ) relative to anterior nasal spine (ANS) so as to provide references for pterygomaxillary separation.

METHODS

The study was based on CBCT images of 109 Chinese patients. We projected Pti and Pts to the frontal plane and measured the distance as well as the positional relationship between the projection points and ANS via three-dimensional reconstruction image.

RESULTS

On average, the ANS was 5.18 mm above the Pti and the horizontal distance between the Pti and ANS was 21.86 mm. The horizontal and vertical distances between Pts and ANS was 20.41 mm and 10.91 mm, respectively. The vertical height of PMJ was 16.09 mm. Scatter plots diagrammatic centered on ANS showed that 73% (160/218) Pti and 64% (140/218) Pts appeared in a 45° fan shape ranged from 20 to 25 mm radius in bilateral inferior and superior quadrant, respectively. There was no significant difference in the distance between both sides (P > 0.05).

CONCLUSION

During the pterygomaxillary disjunction, it exists a risk of injuring neurovascular bundle of the pterygopalatine fossa 16.09 mm above the lowest border of the pterygomaxillary junction. The region within a 45° fan shape ranged in 20-25 mm radius in inferior quadrant centered on ANS might be suitable for the osteotome position. The positional relationship especially between the ANS and Pti found in this study provides a reference for surgeons during pterygomaxillary disjunction.

Surgical Protocol for a Safe Lateral Nasal Wall Osteotomy

PURPOSE

The purpose of this study was to define the anatomy and anatomic variations of the lateral nasal wall area to identify safe access points, determine the optimum osteotomy line for Le Fort I osteotomies, and define a surgical protocol.

MATERIALS AND METHODS

The angulations and widths of 160 lateral nasal walls and the distances of the greater palatine canal were measured on axial images from coronal sections 5 mm over the deepest point of the nasal base.

RESULTS

The average angle between the anterior lateral nasal wall and the medial maxillary sinus wall was 160 degrees in females and 165.67 degrees in males for the right and 155.90 degrees in females and 163.22 degrees in males for the left side. Statistically significant differences were found in the lengths, angulations, and widths of the lateral nasal walls between females and males.

CONCLUSION

This study described the mean angulations and linear distances between anatomic structures of the lateral nasal wall and it defines the "Medipol protocol" for a safe osteotomy.

Evaluation of the Pterygomaxillary Separation Pattern in Le Fort I Osteotomy Using Different Cutting Instruments

PURPOSE

Pterygomaxillary separation (PMS) is considered the main reason for serious complications associated with Le Fort I osteotomy. The aim of this study was to evaluate whether a piezo surgery, ultrasonic bone scalpel, or conventional bur used in Le Fort I osteotomy has an influence on PMS patterns.

MATERIALS AND METHODS

Using a retrospective cohort study design, we enrolled a sample composed of patients who underwent orthognathic surgery. The primary predictor variables were the cutting instruments (ultrasonic bone scalpel, piezo surgery, and Lindeman bur) used to perform Le Fort I osteotomy. Other variables were demographic and anatomic parameters. The outcome variable was the type of PMS pattern, classified as follows: type 1, PMS at the pterygomaxillary junction (ideal PMS); type 2, PMS at the greater palatine foramen; type 3, PMS from the posterior wall of the maxillary sinus; and type 4, PMS with lateral or medial pterygoid fracture. Anatomic parameters, that is, the thickness and width of the pterygomaxillary junction and distance of the greater palatine foramen, were measured on preoperative cone-beam computed tomography images. The pattern of PMS was evaluated on postoperative cone-beam computed tomography. Data were analyzed using analysis of variance and the Pearson χ² test. P < .05 was considered statistically significant.

RESULTS

This study sample was composed of 96 PMSs in 48 patients. The most common type of PMS was type 1 (58), followed by type 4 (21), type 2 (10), and type 3 (7). A statistically significant relation was found between the cutting instrument and the ideal separation (type 1 PMS) pattern (P = .032), and the highest rate of the ideal separation pattern was seen in the ultrasonic bone scalpel group, at 24 of 32, compared with 22 of 38 in the piezo surgery group and 12 of 26 in the conventional bur group.

CONCLUSIONS

According to the study, the ultrasonic bone scalpel is safer than other cutting instruments in terms of the ideal separation of the pterygomaxillary junction.

Morphometric analysis of pterygomaxillary region by using cone beam computed tomography

PURPOSE

Many complications during Le Fort I osteotomy are encountered during pterygomaxillary separation. The study aimed to evaluate the pterygomaxillary region in regards to the Le Fort I osteotomy using cone-beam computed tomography (CBCT) images.

MATERIALS AND METHODS

The CBCT images of 200 patients (100 males, 100 females) aged 18-78 years were evaluated measuring the thickness and width of the pterygomaxillary region, the location of the descending palatine artery, and the length of the pterygoid plates on the axial section.

RESULTS

It has been determined that the distance between the descending palatine canal and the priform rim is longer in males (P=0.037). Medial plate was longer on the right (P=0.0001) and left (P=0.025) in females. The thickness of the pterygomaxillary region was longer in females (P=0.000). The distance between the pterygomaxillary fissure and the descending palatine canal was longer on the right (P=0.001).

CONCLUSION

The pterygomaxillary region may have different anatomies that predispose to specific complications associated with Le Fort I osteotomy. Therefore, before surgery, the pterygomaxillary region should be examined with CBCT, and necessary precautions should be taken preoperatively considering the possible complications.

Computed Tomography Scan Assessment of the Anatomy of the Pterygomaxillary Junction and Its Relevance in Le Fort I Osteotomy

Knowledge of the morphometry and types of pterygomaxillary junction (PMJ) during Le-Fort I osteotomy is an important consideration in the reduction of intraoperative complications. The PMJ is known to display population variations and with the recent increase in these surgical interventions in Kenya, a detailed description of the PMJ is warranted. Computed tomography scan images of PMJ obtained from 63 patients were analyzed at the level of the posterior nasal spine to assess types and the morphometry of the PMJ. A fissure type of PMJ was present in 65.9% (83/126 sides) while a synostosis type was present in 34.1% (43/126). Bilateral fissures were found in 58.73% (37/63), bilateral synostosis in 26.98% (17/63), and an asymmetric PMJ in 15.25% (9/63). The average height, width, and thickness of the PMJ were 17.45 ± 5.26 mm, 10.24 ± 1.97 mm, and 6.40 ± 1.97 mm respectively. Males had a significantly greater height (P = 0.003) and width (P = 0.000). The average width was greater in cases with a synostosis as compared with those with a fissure (P = 0.019). Average distance of greater palatine canal was 40.41 ± 2.28 mm and 7.19 ± 2.20 mm from the piriform rim and the pterygoid fossa respectively. The PMJ among Kenyans is characterized by a higher occurrence of synostosis, greater height, and thickness compared with previous findings from other populations. The results of this study can be helpful for surgeons in selecting the most appropriate techniques to achieve successful pterygomaxillary disjunction and minimize avoid attendant complications such as vascular and nerve injuries.

Anatomical study of the maxillary tuberosity using cone beam computed tomography

OBJECTIVES

To examine the dimensions (width, length, and height) of the maxillary tuberosity (MT) and their correlations with age and sex, and to identify different anatomical types for adequate positioning of miniscrews in this area.

METHODS

The study enrolled 39 patients attending the University of Valencia. The patients comprised 21 males and 18 females with a mean age of 39.7 ± 8.4 years. The dimensions of all 78 MTs were measured on cone beam computed tomography (CBCT) images using Invivo Dental 5 software.

RESULTS

The intraobserver and interobserver errors were good for all measurements. A total of 858 MT measurements were taken. The widths were greater in men than in women, with significant differences. The MT dimensions showed correlations with patient age, whereby older patients presented with greater widths and lengths, but reduced heights. Three different anatomical types were detected according to patient age.

CONCLUSIONS

The dimensions (width, length, and height) of the MT vary according to patient age and sex. The MT dimensions conform to particular anatomical types, which should be taken into account when placing miniscrews in this region.

An Endoscopic Study of the Greater Palatine Nerve

Background

Using an endoscopic approach, lateral sphenoid air cells and terminal branches of the internal maxillary artery often can be accessed through the pterygomaxillary fossa; however, injury to the greater palatine nerve (GPN) can occur if the anatomy of this region is not understood clearly. This study was undertaken to define the pathway of the GPN and to identify landmarks useful in preventing its injury.

Methods

Six cadaveric heads were used to endoscopically dissect and examine 11 pterygomaxillary fossae. An additional latex-injected cadaveric head was sectioned coronally and dissected bilaterally. The relationships between the vascular, neurological and bony structures and foramena were noted and described.

Results

All specimens studied maintained consistent relationships. The sphenopalatine and posterior nasal arteries cross nearly perpendicular and just superficial to the GPN. The GPN traveled anteriorly and inferiorly to reach the greater palatine foramen. The lateral wall of the canal ranged from a thin bony covering to complete dehiscence and was thinnest as it crossed the inferior turbinate and approached the foramen. The foramen rotundum was located lateral and superior to the sphenopalatine foramen near the roof of the maxillary sinus.

Conclusion

When surgically approaching the pterygomaxillary fossa, injury to the GPN is avoidable by thorough knowledge of anatomy and awareness of the described landmarks.

The pterygomaxillary junction: An imaging study for surgical information of LeFort I osteotomy

Maxillary osteotomy is a common surgical procedure and often involves separation of the pterygomaxillary junction (PMJ), which is a “blinded” procedure with inherent risks. Knowledge of the PMJ structure is essential. It remains unclear whether patients with different facial types have different PMJ structures, or different surgical outcome. This study evaluated the computed tomographic images of 283 consecutive patients who received orthognathic surgery. Patients were classified into Angle class I, II, III and cleft lip/palate groups. The results showed that the PMJ was 5.1 ± 1.4 mm in thickness, 9.7 ± 1.7 mm in width, and 102.0 ± 4.0 degrees relative to the sagittal plane in the level of posterior nasal spine. There were no statistically significant differences in these measurements among the groups. The class III group demonstrated significantly smaller angle relative to the maxillary occlusal plane. The cleft group showed significantly longer vertical distance between the posterior nasal spine and the lower border of PMJ, shorter distance between the second molar and PMJ, and longer distance between the descending palatine artery and PMJ. With regard to postoperative outcome, the cleft group showed higher incidence of pterygoid plate fracture. The results in this study provide additional surgical anatomic information.

Relevant Surgical Anatomy of Pterygomaxillary Dysjunction in Le Fort III Osteotomy

BACKGROUND

Le Fort III osteotomy represents the foundation of surgical correction for midface hypoplasia. One serious complication of Le Fort III osteotomy is severing the internal maxillary artery or its branches during osteotome advancement for pterygomaxillary dysjunction. This study sought to characterize the relevant surgical anatomy of the infratemporal fossa and of the internal maxillary artery as it enters the pterygomaxillary fissure.

METHODS

Bilateral midface dissections were performed on 15 fresh, normocephalic adult cadavers (30 hemifaces). Four superficial anatomical measurements were performed on the surface of the face, followed by 10 deep measurements of the internal maxillary artery and its branches relative to the infratemporal fossa and its surrounding bony landmarks.

RESULTS

The distance from the anterosuperior aspect of the zygomatic arch to the sphenopalatine artery entering the pterygomaxillary fissure was 38.9 ± 3.2 mm. The distance from the alveolar process of the maxillary bone to the sphenopalatine artery entry into the pterygomaxillary fissure was 30.3 ± 6.4 mm. The zygomaticofrontal suture was 43.4 ± 8.5 mm from the sphenopalatine artery entry into the pterygomaxillary fissure, 58.8 ± 8.0 mm from the pterygomaxillary junction, and 74.9 ± 6.5 mm from the maxillary alveolar process. The distance from the sphenopalatine artery to the posterior superior alveolar artery was 14.4 ± 4.1 mm. Elevation of the internal maxillary artery from the lateral pterygoid plate was 5.8 ± 2.5 mm.

CONCLUSION

This study characterizes the surgical anatomy of the infratemporal fossa in the context of Le Fort III osteotomies and their associated pterygomaxillary dysjunctions.

Three-dimensional finite element model to predict patterns of pterygomaxillary dysjunction during Le Fort I osteotomy

The aim of this study was to determine whether non-linear three-dimensional finite element analysis (3D-FEA) can be applied to simulate pterygomaxillary dysjunction during Le Fort I osteotomy (LFI) not involving a curved osteotome (LFI-non-COSep), and to predict potential changes in the fracture pattern associated with extending the cutting line. Computed tomography (CT) image data (100 snapshots) after LFI were converted to 3D-CT images. 3D-FEA models were built using preoperative CT matrix data and used to simulate pterygomaxillary dysjunction. The pterygomaxillary dysjunction patterns predicted by the 3D-FEA models of pterygomaxillary dysjunction were classified into three categories and compared to the pterygomaxillary dysjunction patterns observed in the postoperative 3D-CT images. Extension of the cutting line was also simulated using the 3D-FEA models to predict the risk and position of pterygoid process fracture. The rate of agreement between the predicted pterygomaxillary dysjunction patterns and those observed in the postoperative 3D-CT images was 87.0% (κ coefficient 0.79). The predicted incidence of pterygoid process fracture was higher for cutting lines that extended to the pterygomaxillary junction than for conventional cutting lines (odds ratio 4.75; P<0.0001). 3D-FEA can be used to predict pterygomaxillary dysjunction patterns during LFI-non-COSep and provides useful information for selecting safer procedures during LFI-non-COSep.

Distraction osteogenesis as a treatment of obstructive sleep apnea syndrome: A systematic review

BACKGROUND

To conduct a systematic review to answer the clinical question "What are the effectiveness of mandibular distraction osteogenesis (MDO) and its complications to treat patients with obstructive sleep apnea syndrome (OSAS)?".

METHODS

A systematic search including a computer search with specific keywords, reference list search, and manual search were done. Relevant articles on MDO were assessed and selected in 3 rounds for final review based on 5 predefined inclusion criteria and followed by a round of critical appraisal. Different types of distraction and their treatment outcomes of OSAS were recorded with standardized form and analyzed.

RESULTS

Twelve articles were included in the final review. A total of 256 patients aged 7 days to 60 years were treated with either external or internal MDO, with a mean follow-up period of 6 to 37 months. The average distraction distance of 12 to 29 mm was achieved with various distraction protocols. The success rate for adult patients was 100%, and cure rates were ranged from 82% to 100%. The definition of success or cure for OSAS in children or infants was not defined. Therefore, there were no clearly reported success or cure rates for children/infants in the included studies. However, all studies reported that these patients showed significant improvement in OSAS, with many of them who avoided tracheostomy or had the tracheostomy decannulated. The complication rates were ranged from 0% to 21.4%, with most being from local wound infections or neurosensory disturbances.

CONCLUSION

This systematic review showed that MDO was effective in resolving OSAS in adults with retrognathic mandible. MDO also showed promising results in infants or children with OSAS. From the results of this systematic review, we recommend to define the criteria of success or cure for OSAS surgery in children and infants. We also recommend setting up randomized controlled trials to compare MDO with traditional maxillomandibular advancement surgery for OSAS patients and to provide a better evidence on the success and complication rates of the techniques.

Radiologic anatomy of the maxillary artery in the pterygopalatine area applied to Le Fort 1 osteotomies

PURPOSE

In Le Fort 1 osteotomies there is a risk of injuring the maxillary artery, during the pterygomaxillary (PM) disjunction. To improve the knowledge of the relation between the maxillary artery and the PM suture, an anatomic study of the pterygopalatal fossa has been performed.

METHODS

The study was based on CT scan head with vascular injection of the supraaortic trunks in 92 patients. The vertical length of the PM junction and the position of maxillary artery in relation to PM junction have been measured on a parasagittal plane passing through the lateral surface of the PM junction, and on a plane where the PM suture is the highest.

RESULTS

The height of the PM junction on the plane passing through the lateral surface of the PM junction was 6.86 ± 2.67 mm, and the maxillary artery was located 18.22 ± 3.79 mm from the most inferior point of the PM junction. The maximum PM junction height was 13.96 ± 3.03 mm, and at this place the maxillary artery was located 18.85 ± 3.26 mm from the most inferior point of the PM junction. The distance between these two planes was 5.14 ± 2.02 mm.

CONCLUSIONS

According to our results, the height of the PM junction is less than 14 mm and during the PM disjunction there is a risk of injuring the maxillary artery 18 mm above the inferior extremity of the PM junction.

Is an osteotome necessary for pterygomaxillary dysjunction or dysjunction through the tuberosity during Le Fort I osteotomy? A systematic review

Pterygomaxillary dysjunction with an osteotome is commonly used to mobilise the maxilla during Le Fort I osteotomy, despite the risk of serious complications. Different instruments and positions have been tried, including dysjunction through the tuberosity. Down fracture by digital pressure alone has also been advocated, but to our knowledge has not been widely adopted. We have therefore reviewed published papers to see if there is any clinical or anatomical evidence for the use of osteotomes to mobilise the maxilla vertically during a Le Fort I osteotomy for either pterygomaxillary dysjunction or dysjunction through the tuberosity. We found only one paper that analysed the anatomy of the pterygomaxillary fissure and described small bony bridges and syncondroses across the joint. We found no clinical or anatomical evidence for the use of osteotomes in pterygomaxillary separation or separation through the tuberosity. A large clinical trial on down fracture of the maxilla by digital pressure alone showed no serious complications, and we found no strong evidence to justify the use of osteotomes in pterygomaxillary dysjunction or dysjunction through the tuberosity. We have successfully used digital pressure alone in 138 consecutive Le Fort I osteotomies, and we encourage our colleagues to consider adopting this approach.

Adjustable selective maxillary expansion combined with maxillomandibular surgery: A case report

BACKGROUND

Surgically assisted rapid maxillary expansion (SARME) is usually considered the gold standard for maxillary transverse expansion in adults. However, a second surgical procedure is needed in cases of associated sagittal or vertical discrepancies. We describe the use of two new innovative devices for the correction of discrepancies in all dimensions during a single surgical procedure, thus reducing treatment duration.

MATERIAL

We report the case of a 21-year-old female patient, referred to our department for skeletal Class III malocclusion associated with right-side laterognathism and transverse maxillary deficiency. The patient underwent one-stage surgery, using sliding osteosynthesis plates and an adjustable bone-borne distractor. Pre-surgical orthodontics consisted in leveling and aligning the mandibular arch; maxillary leveling was initiated 3 months before surgery. Postoperative palatal distraction combined with orthodontic finishing enabled complete correction of dental and bony discrepancies after 3 months.

CONCLUSION

In our experience, treatment of transverse, sagittal and vertical discrepancies has been possible in a single surgical procedure, using two innovative techniques: sliding osteosynthesis and an adjustable bone distractor. Two years post-surgery, the correction is stable in all dimensions.

Three-dimensional computed tomographic evaluation of bilateral sagittal split osteotomy lingual fracture line and le fort I pterygomaxillary separation in orthognathic surgery using cadaver heads: ultrasonic osteotome versus conventional saw

PURPOSE

The purpose of this study was to observe the quality of the fracture line on the lingual side of the mandible after sagittal split osteotomy and the quality of pterygomaxillary separation after Le Fort I osteotomy using the BoneScalpel ultrasonic osteotome.

MATERIALS AND METHODS

Bimaxillary procedures, according to the standard protocol, were performed using 10 fresh cadaver heads. The ultrasonic osteotome was used in the study group, and a reciprocating saw was used in the control group. Three-dimensional reconstructions of postoperative computed tomographic scans were obtained. The lingual ramus fracture pattern and the pterygomaxillary separation pattern were observed, classified, and compared. Postoperative dissections of the skulls were performed to assess the integrity of the infra-alveolar nerve and the descending palatine artery.

RESULTS

No significant differences were found in the cutting time of bone between the BoneScalpel and the sagittal saw. Of the sagittal split osteotomies in the study group, 90% showed a good pattern (vertical pattern of fracture line extending to the inferior border of the mandible running behind the mandibular canal) compared with 50% of the sagittal split osteotomies in the control group. Ideal separation of the pterygoid plates without fractures was observed in 80% of the Le Fort I osteotomies in the study group compared with 50% of the osteotomies in the control group. High-level fractures occurred in 30% of cases in the control group compared with none in the study group. The integrities of the infra-alveolar nerve and the descending palatine artery were preserved in all cases.

CONCLUSION

Use of the ultrasonic BoneScalpel did not require more time than the conventional method. An improved pattern of lingual fracture lines in mandibular sagittal split osteotomy procedures and the pattern of pterygomaxillary separation in Le Fort I osteotomy procedures were observed.

Preoperative and Postoperative CT Scan Assessment of Pterygomaxillary Junction in Patients Undergoing Le Fort I Osteotomy: Comparison of Pterygomaxillary Dysjunction Technique and Trimble Technique-A Pilot Study

PURPOSE

To determine the rate of complications and occurrence of pterygoid plate fractures comparing two techniques of Le Fort I osteotomy i.e., Classic Pterygomaxillary Dysjunction technique and Trimble technique and to know whether the dimensions of pterygomaxillary junction [determined preoperatively by computed tomography (CT) scan] have any influence on pterygomaxillary separation achieved during surgery.

MATERIALS AND METHODS

The study group consisted of eight South Indian patients with maxillary excess. A total of 16 sides were examined by CT. Preoperative CT was analyzed for all the patients. The thickness and width of the pterygomaxillary junction and the distance of the greater palatine canal from the pterygomaxillary junction was noted. Pterygomaxillary dysjunction was achieved by two techniques, the classic pterygomaxillary dysjunction technique (Group I) and Trimble technique (Group II). Patients were selected randomly and equally for both the techniques. Dysjunction was analyzed by postoperative CT.

RESULTS

The average thickness of the pterygomaxillary junction on 16 sides was 4.5 ± 1.2 mm. Untoward pterygoid plate fractures occurred in Group I in 3 sides out of 8. In Trimble technique (Group II), no pterygoid plate fractures were noted. The average width of the pterygomaxillary junction was 7.8 ± 1.5 mm, distance of the greater palatine canal from pterygomaxillary junction was 7.4 ± 1.6 mm and the length of fusion of pterygomaxillary junction was 8.0 ± 1.9 mm.

DISCUSSION

The Le Fort I osteotomy has become a standard procedure for correcting various dentofacial deformities. In an attempt to make Le Fort I osteotomy safer and avoid the problems associated with sectioning with an osteotome between the maxillary tuberosity and the pterygoid plates, Trimble suggested sectioning across the posterior aspect of the maxillary tuberosity itself. In our study, comparison between the classic pterygomaxillary dysjunction technique and the Trimble technique was made by using postoperative CT scan. It was found that unfavorable pterygoid plate fractures occurred only in dysjunction group and not in Trimble technique group. Preoperative CT scan assessment was done for all the patients to determine the dimension of the pterygomaxillary region. Preoperative CT scan proved to be helpful in not only determining the dimensions of the pterygomaxillary region but we also found out that thickness of the pterygomaxillary junction was an important parameter which may influence the separation at the pterygomaxillary region.

CONCLUSION

No untoward fractures of the pterygoid plates were seen in Trimble technique (Group II) which makes it a safer technique than classic dysjunction technique. It was noted that pterygoid plate fractures occurred in patients in whom the thickness of the pterygomaxillary junction was <3.6 mm (preoperatively). Therefore, preoperative evaluation is important, on the basis of which we can decide upon the technique to be selected for safer and acceptable separation of pterygomaxillary region.

[Sliding osteosynthesis: a new technique for transverse palatal distraction osteogenesis associated with advancement and/or impaction Le Fort I osteotomy]

BACKGROUND

The orthopedic and surgically assisted maxillary expansion is often followed by maxillary advancement osteotomy. The posterior width gain is often small. The expansion is often more extended anteriorly. It impairs posterior correction. The authors describe a new device, ensuring both transversal and sagittal maxillary correction in a single procedure.

MATERIAL AND SURGICAL TECHNIQUE

The sliding internal fixation device is in titanium, 0.8mm thick. It is made up of two plates (Deltex(®), Paris cedex 15, France): an inferior plate with a 45°-angulated slide, a superior plate with a spur. The surgical technique is a Le Fort 1 segmented osteotomy. The distractor is activated between the fifth and 10th postoperative day. Contention is maintained for 1 year after the end of activation.

DISCUSSION

This sliding osteosynthesis technique allows stabilizing the advancement and/or impaction as well as transversal expansion for large transversal deficits in adult patients. This technique avoids performing a second procedure.

Ultrasonic orthognathic surgery: enhancements to established osteotomies

The use of a novel ultrasonic osteotome enabled the authors to modify well-established orthognathic osteotomies to more favourably address the anatomy. For this purpose, they utilized a powerful ultrasonic device with tissue-selective cutting characteristics that was originally developed for spinal osteotomies and nerve decompression (BoneScalpel™ by Misonix Inc., Farmingdale, NY, USA). Its straight ultrasonic blade was adapted for dual action, and a soft protective element was added. The product modifications and the related changes regarding maxillary and mandibular osteotomies are explained in detail. A series of 83 patients underwent orthognathic surgery with the BoneScalpel ultrasonic osteotome. All osteotomies within this study group were performed purely ultrasonically and without the auxiliary use of reciprocating saws or rotary burrs. The complications, alveolar nerve impairment and bad splits were assessed. To assess the quality of the lingual osteotomies and pterygomaxillary separation, three-dimensional scanning was performed on 30 patients. In conclusion, the BoneScalpel™ ultrasonic osteotome enabled improved control over orthognathic osteotomies and resulted in significant reductions in the occurrence of nerve impairment and bad splits.

Factors predictive of pterygoid process fractures after pterygomaxillary separation without using an osteotome in Le Fort I osteotomy

OBJECTIVE

This study demonstrated pterygomaxillary disjunction patterns and elucidated factors related to unfavorable pterygomaxillary junction fractures in Le Fort I osteotomy without using an osteotome.

STUDY DESIGN

Clinical and anatomical data obtained from computed tomography images (100 sides) were analyzed for their ability to predict patterns of pterygomaxillary disjunction.

RESULTS

Separation of the pterygomaxillary junction was most frequently performed at the maxillary tuberosity (48.0%). Twenty-eight pterygoid plates were fractured. Male gender, increased age, thickness of the pterygomaxillary junction, and length of the maxillary tuberosity were significant risk factors for pterygoid process fractures. We also identified that a pterygomaxillary junction thickness less than 2.6 mm and a maxillary tuberosity length of more than 11.5 mm indicated a statistically significant risk of pterygoid process fractures.

CONCLUSIONS

Prediction of frangible pterygoid plates by preoperative quantitative evaluation of morphometric values provides useful information for selecting safe procedures.

Influence of third molars in Le Fort 1 osteotomy

Background:

The influence of maxillary third molar (M3) on the outcomes of Le Fort 1 osteotomy is not deeply investigated.

Aim:

To investigate the influence of M3 on Le Fort 1 osteotomies.

Setting:

Tertiary Referral Center, operated by a single surgeon, prospective study.

Period:

January 2005 to December 2010.

Patients:

Consecutive Le Fort 1 osteotomy patients with both M3.

Predictor Variable:

Gender, position, M3 root morphology, and degree of impaction.

Outcome Variable:

Time taken after all osteotomy cuts to point of time when maxilla is placed in predetermined plane.

Result:

A total of 658 M3 in line of cut were studied. Of all M3, 312 were impacted, 28.9% were partially impacted and 23.7% were erupted. Of all the M3, 2.9% had their cuspal tips above the horizontal cut, 13.8% along the line of cut, and in 20.7% below the line but not erupted. Buccoverted tooth took shortest time (7.74 minutes), while palatoversion required more time (8.44 minutes) (P = 0.000). When the cuspal tip of M3 was located above the horizontal line of cut, the mean time required to achieve the planned position was 7 minutes, while the completely erupted teeth took a mean of 8.24 minutes (P = 0.000).

Conclusion:

When the M3 is placed higher, it takes lesser time to prepare basal bone to receive the maxilla at its predetermined level. Angulation of M3 influences the outcome. Deeply placed M3 reduces the manipulation of the greater pterygoid palatine vessels in the area thereby minimizing the bleeding in the surgical field.

Orthognathic Treatment with Autotransplantation of Impacted Maxillary Third Molar

This article presents orthognathic treatment in successful collaboration with autotransplantation of the maxillary third molar. The case report describes a 24-year-old man with severe mandibular protrusion and severe crowding in both dentitions. Overbite was 0 mm, overjet, −15 mm. Maxillary second molars and mandibular third molars were extracted, and presurgical multibracket treatment was begun. Maxillary third molars were impacted completely at 18 months in terms of presurgical tooth alignment. Autotransplantation of the teeth was achieved to substitute for extracted maxillary second molars. At 6 months after autotransplantation, the maxilla was advanced 4 mm on both sides through a Le Fort I procedure; left and right sides of the mandible were set back 15 and 18 mm, respectively, via sagittal split ramus osteotomy to improve mandibular protrusion. The total treatment period lasted 37 months. Autotransplantation treatment is an effective modality for tooth replacement when a donor tooth is available. Fully impacted maxillary third molars are potentially reliable candidates for autotransplantation.

Prospective study of the incidence of serious posterior maxillary haemorrhage during a tuberosity osteotomy in low level Le Fort I operations

The incidence of serious haemorrhage in Le Fort I osteotomy is low and attempts to reduce this further have led to the development of various techniques to minimise vascular injury. This includes the tuberosity osteotomy and was published over two decades ago. This technique has not been widely adopted as shown by a recent UK survey of consultants, which suggested that only 12 (7%) of the 175 surgeons who responded, routinely use tuberosity osteotomy in non-cleft low level Le Fort I procedures. The aim of the study was to examine prospectively the incidence of serious haemorrhage from the posterior maxilla during tuberosity osteotomy. We report 35 consecutive patients who have had no operative or postoperative vascular complications.

Anatomy of greater palatine foramen and canal and pterygopalatine fossa in Thais: considerations for maxillary nerve block

This study aims to investigate the anatomy of the greater palatine foramen (GPF), greater palatine canal (GPC) and pterygopalatine fossa (PPF) with special reference to the blockage of the maxillary nerve. A correlation between the length of GPC and PPF and the heights of the orbit and the maxilla was also studied using simple linear regression analysis. The morphology of the GPF, GPC and PPF as well as heights of the orbit and the maxilla were assessed in 105 Thai skulls. The thickness of the mucosa over the GPF was also measured from the dissection of 55 cadavers. The results showed that most GPF appeared as an oval foramen located at the palatal aspect of the upper third molar. The GPF was 16.2+/-1.3 mm lateral to the median sagittal plane of the hard palate, 2.1+/-1.3 mm anterior to the posterior border of the hard palate and 5.1+/-1.3 mm from the greatest concavity of the distolateral margin of the hard palate. The mean length of GPC and PPF was 29.7+/-4.2 mm. The mean angles of the GPC in relation to the hard palate and the vertical plane were 57.9+/-5.8 degrees and 6.7+/-5.2 degrees , respectively. In attempting to insert a needle to reach the foramen rotundum through the GPF, 31.7% passed into the orbit while 8.7% passed into the brain. The mean thickness of the mucosa over GPF was 6.7+/-2.3 mm. Two models for estimating the depth of needle injection in maxillary nerve block have been developed as follows: Length of GPC and PPF=19.038+0.314 (orbital height) and length of GPC and PPF=21.204+0.187 (maxillary height). The calculated length combined with the mucosal thickness was the estimated depth of needle injection. In conclusion, our results concerning the GPF, GPC and PPF will provide the useful reference for clinicians to anesthetize the maxillary nerve with a greater degree of success.

Clinical anatomy of the posterior maxilla pertaining to Le Fort I osteotomy in Thais

This article studies the anatomy of the posterior maxilla pertaining to bone-cut design of Le Fort I osteotomy to avoid the injury to the descending palatine artery in Thais. Fifty-five skulls (38 males, 17 females) were assessed for the anatomical landmarks by a combination of direct inspection, computerized imaging, and computed tomography scan analysis. The results showed that 27.28% of the pterygomaxillary junction (PMJ) became synostosis. The mean heights of the PMJ, posterior maxilla, and maxillary tuberosity were 15.14 +/- 2.46 mm, 22.51 +/- 3.50 mm, and 7.45 +/- 2.76 mm, respectively. The mean length of the medial sinus wall measuring from the piriform rim to the descending palatine canal at the Le Fort I level was 34.40 +/- 2.96 mm. The mean widths of the posterior incision of Le Fort I osteotomy at the maxillary tuberosity and PMJ were 20.38 +/- 2.82 mm and 11.60 +/- 1.57 mm. The mean length of the posterior maxilla was 27.18 +/- 2.49 mm. Distances from the greater palatine foramen to the maxillary tuberosity incision and PMJ incision were 1.76 +/- 1.12 mm and 3.59 +/- 1.40 mm. The mean angle between the descending palatine canal and the hard palate was 57.33 +/- 4.54 degrees . There were no significant differences in any measurements between sides and genders, except the pterygoid process width and posterior maxilla length of males were longer than those of females (P < 0.05). This study could provide better understanding of the posterior maxillary anatomy that is important for the bone-cut design of Le Fort I osteotomy to avoid excessive intraoperative and postoperative hemorrhage including ischemia of the mobilized maxilla.

Stability consideration for internal maxillary distractors

PURPOSE

Stability in distractor design ensures distraction osteogenesis healing with good bone regenerate formation. The aim of this study was to compare the holding strengths of different fixation systems for maxillary distractor design on bone pieces of different thicknesses.

MATERIAL AND METHODS

Cross-sectional images of 10 dry skulls were obtained by computer tomography and the bone thickness of the maxillae were measured according to five individual anatomical regions (paranasal, infra-orbital, posterior sinus wall, zygomatic and alveolar regions). According to the measurements, the screws of 1.5 and 2mm in diameter and the three-screw mini-plates in triangular and straight configurations were evaluated for holding strength by pull-out tests on fresh animal bone pieces of defined thickness.

RESULTS

The paranasal and zygomatic regions of the human skulls had the thickest cortical bone (4mm) followed by the alveolar region (2mm). In the bones of 2 and 4mm thickness, the 2mm screws were confirmed stronger than the 1.5mm ones in pull-out tests. However, the pull-out behaviour of screws of different diameters in 1mm thick bones and the mini-plates in two different configurations showed no significant differences.

CONCLUSION

This study confirms that the paranasal and zygomatic bones are the thickest for fixation of internal maxillary distractors. Fixation screws of 2mm diameter in either triangular or straight miniplates can produce good stabilization for distractors.