Nasomaxillary Buttress Research Articles

Evaluation of cortical bone thickness at the nasomaxillary and zygomaticomaxillary buttresses using cone-beam computed tomography imaging for Le Fort I osteotomy

Background/PurposeStudies have indicated that 50%–55% of the population have malocclusion, and approximately 5%–10% require orthognathic surgery to correct this condition. Optimal placement of plates and screws significantly affects the success rate of the surgery and postoperative stability. This study evaluates the cortical thickness of the maxillary bone in the nasomaxillary and zygomaticomaxillary buttress regions in Taiwanese patients based on cone-beam computed tomography (CBCT) images. Materials and methods128 Patients undergoing Le Fort I osteotomy were selected for this study. Their CBCT images were input into medical imaging software to simulate the placement of titanium screws and plates. The cortical bone thickness at these positions was measured to assess the thickness in the nasomaxillary buttress (surrounding the nasal opening) and the zygomaticomaxillary buttress (surrounding the maxillary zygomatic process). Associations of these thicknesses with gender, age, and screw position were analyzed. ResultsIn the nasomaxillary region, cortical bone was thicker on the upper and lower vertical regions, with men generally having thicker bone. The zygomaticomaxillary region had increased thickness near the zygomatic end and distal region. Younger adults had significantly greater bone thickness in certain areas than those over 30 years. ConclusionThe nasomaxillary region's upper and lower vertical regions and the zygomatic end in the zygomaticomaxillary region provide optimal screw placement sites. Bone thickness differences by gender and age suggest occlusal force and age-related bone resorption as influencing factors.

Minimally invasive technique for anterior maxillary intrusion - A series of 7 cases with 1year follow-up

Objective: The conventional treatment for Anterior Maxillary Vertical Excess (AMVE) is surgical reduction and rigid fixation which has low patient acceptance. However, intrusion of some selected AMVE cases can be achieved with minimal intervention using micro plate anchorage, thus expediting and simplifying their management. The present paper demonstrates the efficacy of microplate anchorage in the intrusion of anterior maxilla. Methods: A total of 7 patients (2 males and 5 females) in the age group of 13–43 years were treated for anterior maxillary vertical excess. Anterior maxillary intrusion was carried out using two hole microplates anchored bilaterally at the naso maxillary buttress and closed coil spring attached to the arch wire. The activation was carried out at monthly interval. Results: The mean duration of surgical procedure was 18.4 minutes and the mean duration for intrusion was 4.86 months (3–7 months). The patients compliance were overall good and the average amount of intrusion achieved was 4.14 mm. All the patients were satisfied with post treatment smile. Conclusion: The result of this study elucidates that intrusion using micro plates is an easy, efficient, safe and cost effective option in the management of AVME. It is less invasive with acceptable clinical and radiographic outcome. Careful case selection is needed for achieving satisfactory result and smile.

Lacrimal Duct Obstruction Caused by Nasomaxillary Fracture: A Retrospective Analysis of Consecutive 12 Patients by Computed Tomographic Dacryocystography.

Nasomaxillary fracture is a characteristic mid-facial fracture, and there are no reports showing the fracture damaging the nasolacrimal system (NLS). This report described nasomaxillary fracture cases with NLS damages, which were assessed by computed tomographic dacryocystography (CT-DCG). A retrospective cohort study of nasomaxillary fractures diagnosed by CT was conducted from 2007 to 2015. Twelve patients (mean age: 27.5 years) were found, and their clinical symptoms were as follows: nasal deformity in 10 patients, infra-orbital hypoesthesia in 7, epiphora in 5, and diplopia in one. CT-DCG was performed for 2 patients who complained epiphora, and obstruction was found in 1 patient. All patients underwent open reduction and internal fixation (ORIF), and epiphora in 5 patients was improved. One patient, however, complained epiphora postoperatively, which was supposed to be due to the unsuitable screw insertion. Since nasomaxillary fracture could give NLS obstruction, CT-DCG is useful for diagnosis. Although ORIF is an optimal treatment, attention is needed to avoid the lacrimal canal in screwing on the nasomaxillary buttress.

Tomographic analysis of nasomaxillary and zygomaticomaxillary buttress bone thickness for the fixation of miniplates

The purpose of this study was to evaluate the bone thickness of the nasomaxillary and zygomaticomaxillary buttresses to identify the most favourable region for the installation of miniplates. Bilateral tomographic images of 103 individuals were evaluated, for a total of 206 nasomaxillary and zygomaticomaxillary buttresses. Measurements of bone thickness were performed in the parasagittal reconstructions along three vertical lines on the nasomaxillary buttress (21 measurement points) and four vertical lines on the zygomaticomaxillary buttress (28 measurement points). The vertical line measurements for each buttress were compared using the Kruskal–Wallis test. Spearman’s correlation coefficient was used to determine the correlation between the thicknesses obtained and patient sex and side (right/left). The level of significance adopted was 5%. The nasomaxillary and zygomaticomaxillary buttresses presented statistical differences in thickness at their respective points (P=0.001). The analysis of the nasomaxillary buttress showed that the thicker bone for the installation of miniplates follows the long axis of the upper canine at a distance of 3mm from the root apex. For the zygomaticomaxillary buttress, thicker bone to install miniplates was found distal to the distobuccal root of the first molar, at a distance of 3.5mm from the limit of the infraorbital foramen.

Two-point nasomaxillary fixation of the Le Fort I osteotomy: assessment of stability at one year postoperative

The purpose was to assess maxillary position among patients undergoing Le Fort I maxillary advancement with internal fixation placed only at the nasomaxillary buttresses. This was a retrospective study of patients undergoing a Le Fort I osteotomy for maxillary advancement, with internal fixation placed only at the nasomaxillary buttresses. Demographic and cephalometric measures were recorded. The outcome of interest was the change in maxillary position between immediately postoperative (T1), 6 weeks postoperative (T2), and 1 year postoperative (T3). Fifty-eight patients were included as study subjects (32 male, 26 female; mean age 18.4±1.8 years). Twenty-five subjects (43.1%) had a diagnosis of cleft lip and palate. Forty-three subjects (74.1%) had bimaxillary surgery, 16 (27.6%) had bone grafts, and 18 (31.0%) had segmental maxillary osteotomies. At T3, there were no subjects with non-union, malunion, malocclusion, or relapse requiring repeat surgery. Mean linear changes between T1 and T3 were ≤1mm. Mean angular changes between T1 and T3 were <1°. There was no significant difference in stability in multi-segment maxillary osteotomies (P= 0.22) or with bone grafting (P= 0.31). In conclusion, anterior fixation alone in the Le Fort I osteotomy results in a stable maxillary position at 1 year postoperative.

BIOMECHANICAL ANALYSIS TO VERIFY THE BUTTRESS THEORY WHEN USING THE ANATOMICAL THIN TITANIUM MESH PLATE FOR ZYGOMATICOMAXILLARY COMPLEX BONE FRACTURE

Objective: The aim of this study was to investigate the biomechanics of the facial skeletal for understanding the buttress after fixation with standard and modified anatomical thin titanium mesh (ATTM) plates by finite element (FE) analysis. Methods: Standard ATTM (SATTM) plate designed as the “L”-shape anticipated to be fixed in the ZMC anterior maxilla and lateral buttress to increase the fixation screw anchoring strength and another modified ATTM (MATTM) plate with a protrusion in the medial side and a slot and barb design in the lateral side to enhance the zygomaticomaxillary/nasomaxillary buttresses and provide precise positioning to the ZMC segments were studied by the FE analysis under masticatory forces with 250[Formula: see text]N. Result: The FE simulation results indicated that the total displacement distribution of the maxillary for ZMC fracture fixation with MATTM plate was smaller than that of SATTM plate. Stress concentration was found at the frontal and alveolar processes of the maxillary bone for SATTM plate fixation. Local vector plots of the first principal stress near the frontal process of the maxillary and zygomaticofacial formen of the zygomatic indicated that the stress flow for MATTM plate fixation was relatively close to nasomaxillary buttress, and the zygomaticomaxillary buttress, respectively. Conclusions: This study concluded that “L”-shape ATTM plate designed with a protrusion in the medial side and a slot and barb design in the lateral side can enhance the zygomaticomaxillary/nasomaxillary buttresses under uniform occlusal condition.

Midface Distraction Osteogenesis Using a Modified External Device With Elastic Distraction for Crouzon Syndrome.

Midface distraction osteogenesis has been popularized for the correction of midface hypoplasia associated with exophthalmos and obstructive sleep apnea in patients with Crouzon syndrome. The purpose of this study was to present the method of utilizing the modified external device with elastic distraction for the midface advancement in Crouzon syndrome, and the clinical outcomes and skeletal changes were analyzed. Five consecutive patients with Crouzon syndrome underwent Le Fort III osteotomy with midface advancement using a modified external device with elastic distraction. The distraction system consists of a rigid external distractor, nickel-titanium shape memory alloy spring, and bone-borne traction hooks. The midface advancement was initiated with the bony anchorage around the nasomaxillary buttress at the level between occlusal plane and infraorbital margin. The device was activated at a rate of 1 to 1.5 mm per day by the length of spring. The skeletal changes were analyzed by cephalometric and computed tomographic measurement. All the patients achieved improvements in midface appearance, obstructive sleep apnea, exophthalmos, and occlusion. No complications occurred during this procedure. After the distraction, 1 patient developed an open bite that was corrected by a definitive orthognathic surgery. Cephalometric and computed tomographic measurement analysis showed a differential advancement of midface with more at the occlusal level than the orbital level. In addition, midface suture and bone remodeling was also observed in growing patient. Our modified external device with elastic distraction offers an alternative method to achieve midface advancement in patients with Crouzon syndrome.

Structural biomechanics of the craniomaxillofacial skeleton under maximal masticatory loading: Inferences and critical analysis based on a validated computational model

The trend towards optimizing stabilization of the craniomaxillofacial skeleton (CMFS) with the minimum amount of fixation required to achieve union, and away from maximizing rigidity, requires a quantitative understanding of craniomaxillofacial biomechanics. This study uses computational modeling to quantify the structural biomechanics of the CMFS under maximal physiologic masticatory loading. Using an experimentally validated subject-specific finite element (FE) model of the CMFS, the patterns of stress and strain distribution as a result of physiological masticatory loading were calculated. The trajectories of the stresses were plotted to delineate compressive and tensile regimes over the entire CMFS volume. The lateral maxilla was found to be the primary vertical buttress under maximal bite force loading, with much smaller involvement of the naso-maxillary buttress. There was no evidence that the pterygo-maxillary region is a buttressing structure, counter to classical buttress theory. The stresses at the zygomatic sutures suggest that two-point fixation of zygomatic complex fractures may be sufficient for fixation under bite force loading. The current experimentally validated biomechanical FE model of the CMFS is a practical tool for in silico optimization of current practice techniques and may be used as a foundation for the development of design criteria for future technologies for the treatment of CMFS injury and disease.

A Reduction Technique for a Depressed and Impacted Nasomaxillary Buttress Fracture

The aim of this study is to introduce an easy method of reducing the depressed and impacted segment in a nasomaxillary buttress fracture.Through the gingiva-labial vestibular incision, the fracture segments were exposed. A blunt end of the Cottle elevator was inserted to the cleft of the fracture segments. An upward and lateral force was applied until the impacted segment was released and reduced to its anatomical position. Then, the segments were fixed with a miniplate.Fifteen patients (12 males, 3 females, mean age: 34.5 ± 11.7 years) were operated on. In 14 patients, the fragments were reduced in the anatomical position and secondary surgery was not required. In 1 patient, however, the infraorbital rim could not be reduced enough through a gingival incision and a secondary surgery was performed to reduce the orbital rim.A blunt end of the Cottle elevator is shallow and long enough to be inserted into the cleft and strong enough to transfer the force to reduce it into its anatomical position. This reduction technique using a Cottle elevator is easy and can be used for reducing the depressed and impacted segment in nasomaxillary buttress fractures.

Nasolacrimal System Fractures: A Description of Radiologic Findings and Associated Outcomes.

Fractures of the bony nasolacrimal system (NLS), including the lacrimal sac fossa and nasolacrimal canal, have not been comprehensively described in patients with facial trauma. Characterization of these injuries may help facial trauma surgeons better predict which patients will develop lacrimal outflow obstruction symptoms including epiphora and dacryocystitis and who may eventually need lacrimal surgery. CT images for all patients seen at the University of Wisconsin Hospital and Clinics for craniofacial trauma were reviewed from January 2001 to December 2005. Patients were included if they had a NLS fracture and at least 1 year of follow-up. Fracture patterns were described and correlated with clinical outcomes documented in the medical record. Outcomes, including the development of epiphora or dacryocystitis and the need for lacrimal surgery, were analyzed using Fisher exact test. We identified 104 patients with NLS fractures among 1980 patients with craniofacial trauma who had at least 1 year of follow-up. Eleven patients (10.6%) developed epiphora or dacryocystitis, and 2 patients (1.9%) required dacryocystorhinostomy (DCR). Ten radiographic injury patterns were characterized. Avulsion of the lacrimal crest, bone fragment in the lacrimal sac fossa or duct, duct compression greater than 50%, and nasomaxillary buttress displacement were significantly associated with the development of epiphora or dacryocystitis (P < 0.05). Nasomaxillary buttress displacement was significantly associated with the eventual need for DCR (P = 0.03). Patients with radiographic evidence of NLS fracture have an approximately 10% risk of developing epiphora or dacryocystitis. We describe 5 NLS fracture findings that are significantly associated with the development of lacrimal outflow obstruction. The presence of nasomaxillary buttress fracture and displacement suggests a significantly higher risk of eventually needing lacrimal surgery.

Medial maxillary fractures revisited

We consider medial maxillary fractures to be a unique type of nasomaxillary buttress fracture involving the lateral margin of the piriform aperture, the maxillary frontal process and the medial aspect of the infraorbital rim. This article aims to define medial maxillary fractures as a unique type of facial bone fracture. Eight patients with medial maxillary fractures were treated at our hospital from May 2010 to June 2013. Every patient was preoperatively evaluated using three-dimensional and multidimensional computed tomographic scans and surgically treated. The subjects were seven men and one woman (mean age: 17.5 years). The common mechanism of injury was interpersonal impact followed by small object impact. All of the patients exhibited epistaxis and hypoaesthesia affecting the maxillary nerve and/or its branches, and some patients also displayed nasal deformities and/or diplopia. An oral approach was employed in every case, and it was combined with a subciliary approach in some cases. Medial maxillary fractures involve the maxilla, lacrimal bone, ethmoid bone and/or nasal bone. The main difference between medial maxillary fractures and nasoethmoid orbital fractures is the bones they affect. Medial maxillary fractures are a unique type of nasomaxillary buttress fracture and should be classified as such because of the bones they affect, their symptoms and the surgical approaches used to treat them.

Finite element study of maxillary Le Fort-I osteotomy with rigid internal fixation

To study the biomechanical characteristic of maxillary Le fort- I osteotomy with rigid internal fixation (RIF) , so as to choose best fixation method. The 3-dimensional finite element models of maxillary Le Fort-I osteotomy with 9 kinds of RIF methods were established. Then the models were divided into three groups to calculate the stress distribution of the maxilla and the displacement of bone segment under 3 kinds of occlusion condition. The fixation stability of the different RIF methods was evaluated. Under the incisor occlusion condition, the stress of the cranio maxillary complex transmits mainly along the nasal-maxillary buttress. Under the premolar and molar occlusion condition, the stress transmits along the alveolar process first, then turns to the nasal-maxillary and zygomatic-maxillary buttress. The focused stress position of the internal fixation system is at the connection between the screws and the plate and at the plate near the osteotomy line. Under the premolar occlusion condition, the displacement of bone segment with different RIF methods was (in a decreasing order) 0.396509 mm (with bio-absorbable plate), 0.148393 mm (with micro-plate ), 0.078436 mm (with mini-plate) in group 1; 0.188791 mm (fixing at the nasal-maxillary buttress), 0.121718 mm (fixing at the zygomatic-maxillary buttress), 0.078436 mm (fixing at the both buttress) in group 2; 0.091023 mm (with straight plate), 0.078436 mm (with L shape plate), 0.072450 mm (with Y shape plate), 0.065617 mm (with T shape plate) in group 3. The fixation stability of using the bio-absorbable plate in Le Fort-I osteotomy is less stable than using the titanium plate. Fixing at the zygomatic-maxillary buttress is more stable than at the naso-maxillary buttress. The fixation stability is different by using different shapes of plates.

Trends in Functional Rhinoplasty

The evolution of the rhinoplastic surgery has spanned several centuries, with the last few decades focused on the development and refinement of techniques that address the nasal airway specifically. This increased focus on functional rhinoplasty has led to significant improvements in our ability to preserve and augment the nasal airway. Techniques are generally categorized by their effects on the external and/or internal nasal valves. Limitations exist, however, in our ability to critically interpret and apply these techniques due to a dearth of validated and reliable outcomes measures as well as confusion regarding the nomenclature of the nasal valves. This chapter will present a brief introduction to the history of functional rhinoplasty, means of evaluating the nose, outcomes, and surgical treatment of the nasal airway during functional rhinoplasty.

Mid-facial reconstruction after maxillectomy

Reconstruction following extensive resection of the maxilla has been a challenging problem in the field of head and neck cancer surgery. At our institutes, maxillectomy defects have been restored based on the principles of repair involving the important concept of maxillary buttress reconstruction. Reconstruction of the zygomaticomaxillary buttress (ZMB), including the orbital floor, is essential for prevention of the malpositioning of the eyeglobe in preservation of the orbital contents. ZMB reconstruction is also important to provide a good contour of malar prominence. Pterygomaxillary buttress (PMB) reconstruction provides sufficient support for the fitting of a dental prosthesis. In patients with extensive resection of buccal soft tissue, a PMB and nasomaxillary buttress (NMB) should be reconstructed to prevent superior and posterior deviation of the alar base and oral commissure. We advocate that critical assessment of skeletal defects, as well as associated soft-tissue defects, following various types of maxillectomies is essential for a rational approach to achieve satisfactory clinical results.

Rigid Stabilization of Sagittal Fractures of the Maxilla and Palate

Rigid stabilization of sagittal fractures of the palate is described that utilizes plate and screw fixation in the palatal vault. Accurate reduction of facial width is obtained, and stability is significantly enhanced. An existing laceration or a longitudinal incision in the palatal mucoperiosteum provides exposure for maxillary adaption plate application. The transpalatal reduction should be supplemented by fixation at the piriform aperture, the zygomaticomaxillary and nasomaxillary buttresses, and by the use of an arch bar. Since slower bone healing may be observed following palatoalveolar fractures, the occlusion must be observed for deviation throughout a full 16-week period even though early motion and soft diet are permitted. Removal of the plate and screws in the roof of the mouth is sometimes required and utilizes local anesthesia.

Midface Fractures

Experience with 240 midface (Le Fort and zygoma) fractures in multiple trauma patients has emphasized that superior aesthetic results are obtained by immediate extended open reduction with primary bone grafting. Internal fixation of 110 zygomatic and 130 Le Fort fractures was performed in the lower midface (zygomaticomaxillary and nasomaxillary buttresses). Open reduction of the condyle was employed in five concomitant Le Fort and subcondylar fractures with a loss of ramus height to prevent superior and posterior displacement of the middle and lower face. Bone grafts were utilized in 74 patients. They were most frequently employed in the orbit and less frequently in the lower midface. Bone graft survival paralleled that observed under elective conditions, and a slightly higher infection rate was observed. Extended open reduction and immediate bone grafting adds a new dimension to the aesthetic results obtained from facial fracture treatment. Structural bony integrity and pre-injury facial architecture may be restored in the absence of soft-tissue contracture. Restoration of the pre-injury facial architecture (the essence of facial fracture treatment) is more accurately accomplished when these techniques are utilized.