Mandibular Process Research Articles

Directed Bmp4 expression in neural crest cells generates a genetic model for the rare human bony syngnathia birth defect

Congenital bony syngnathia, a rare but severe human birth defect, is characterized by bony fusion of the mandible to the maxilla. However, the genetic mechanisms underlying this birth defect are poorly understood, largely due to limitation of available animal models. Here we present evidence that transgenic expression of Bmp4 in neural crest cells causes a series of craniofacial malformations in mice, including a bony fusion between the maxilla and hypoplastic mandible, resembling the bony syngnathia syndrome in humans. In addition, the anterior portion of the palatal shelves emerged from the mandibular arch instead of the maxilla in the mutants. Gene expression assays showed an altered expression of several facial patterning genes, including Hand2, Dlx2, Msx1, Barx1, Foxc2 and Fgf8, in the maxillary and mandibular processes of the mutants, indicating mis-patterned cranial neural crest (CNC) derived cells in the facial region. However, despite of formation of cleft palate and ectopic cartilage, forced expression of a constitutively active form of BMP receptor-Ia (caBmprIa) in CNC lineage did not produce the syngnathia phenotype, suggesting a non-cell autonomous effect of the augmented BMP4 signaling. Our studies demonstrate that aberrant BMP4-mediated signaling in CNC cells leads to mis-patterned facial skeleton and congenital bony syngnathia, and suggest an implication of mutations in BMP signaling pathway in human bony syngnathia.

Fractures of the mandibular coronoid process: A two centres study

The aim of this study was to assess the characteristics of patients with coronoid fractures treated in two European centres over 10 years and to briefly review the literature.This study is based on 2 systematic computer-assisted databases that have continuously recorded patients hospitalized with maxillofacial fractures and surgically treated in two European centres between 2001 and 2010.During the 10 years, 1818 patients and 523 patients with maxillofacial fractures were admitted to the two centres respectively: 21 patients (16 males, 5 females) were admitted with 21 coronoid fractures and 28 associated maxillofacial fractures.A mean age of 42.1 years was observed. The fractures were mainly the result of motor vehicle accidents, followed by assaults and falls. The most frequently observed associated maxillofacial fracture was a zygomatic fracture (13 fractures). In both centres, mandibular coronoid fractures are treated unless a severe dislocation of the fractured coronoid is observed or a functional mandibular impairment is encountered.Conservative treatment can be used, together with the open reduction and internal fixation of associated fractures. The crucial point is to prevent ankylosis, which may be prevented by correct and early postoperative physiotherapy and mandibular function.

Reasons for mini-implants failure: choosing installation site should be valued!

Mini-implant loss is often associated with physical and mechanical aspects that result from choosing an inappropriate placement site. It is worth highlighting that:a) Interdental alveolar bone crests are flexible and deformable. For this reason, they may not offer the ideal absolute anchorage. The more cervical the structures, the more delicate they are, thus offering less physical support for mini-implant placement; b) Alveolar bone crests of triangular shape are more deformable, whereas those of rectangular shape are more flexible; c) The bases of the alveolar processes of the maxilla and the mandible are not flexible, for this reason, they are more likely to receive mini-implants; d) The more cervical a mini-implant is placed, the higher the risk of loss; the more apical a mini-implant is placed, the better its prognosis will be; e) 3D evaluations play a major role in planning the use of mini-implants.Based on the aforementioned considerations, the hypotheses about mini-implant loss are as follows:1) Deflection of maxillary and mandibular alveolar processes when mini-implants are more cervically placed; 2) Mini-implants placed too near the periodontal ligament, with normal intra-alveolar tooth movement; 3) Low bone density, low thickness and low alveolar bone volume; 4) Low alveolar cortical bone thickness; 5) Excessive pressure inducing trabecular bone microfracture; 6) Sites of higher anatomical weakness in the mandible and the maxilla; 7) Thicker gingival tissue not considered when choosing the mini-implant.

Macrostomia

Macrostomia is a rare facial cleft, with an incompletely described pathogenesis. This series highlights cases of isolated macrostomia presenting with several distinct phenotypes. We examine phenotypic differences in macrostomia patients, to further elucidate the etiopathogenesis. We performed a retrospective review of macrostomia patients evaluated during a 10-year period. Patient demographics and clinical features are reported. We identified 25 macrostomia patients (13M/12F). Right-sided macrostomia occurred in 15, left-sided macrostomia occurred in 6, and bilateral macrostomia occurred in 4 patients. Of the bilateral cases, 100% existed in isolation of craniofacial microsomia (CFM) or other craniofacial abnormalities. Twelve patients presented with macrostomia in isolation of CFM; in this subgroup, the male-to-female ratio was 1:1. Bilateral macrostomia was present in 33% of patients. Unilateral macrostomia occurred more often on the right (5:2). Phenotypes included simple unilateral or bilateral macrostomia (67%), macrostomia associated with severe diastasis of the cheek musculature (8%), macrostomia associated with lateral facial clefts (17%), and diastasis of cheek musculature without significant macrostomia (8%). Macrostomia seen in isolation of CFM presents in phenotypically distinct forms. It is unlikely that a single mechanism is responsible for this range of phenotypes. We believe that both intrauterine trauma and failure of fusion of the mandibular and maxillary processes secondary to an aberration in FGF8 function are responsible. Additionally, diastasis of facial musculature may result from delayed fusion and subsequent decreased mesodermal penetration of the mandibular and maxillary processes.

MANAGEMENT OF ATYPICAL MANDIBULAR CORONOID PROCESS ELONGATION WITH BILATERAL INTRAORAL CORONOIDOTOMY

Bilateral coronoid hyperplasia is characterized by a progressive limitation in mandibular movement secondary to mechanical impingement of the elongated coronoid processes on the posterior surface of the zygomatic bones. The etiology of coronoid hyperplasia remains uncertain, with various proposed theories. As it is an unusual and infrequent clinical entity, hyperplasia of the coronoid process is often overlooked or diagnosed too late. A 27-year old, ASA I, male patient referred to our clinic because of his restricted mouth opening. Bilateral coronoid hyperplasia was detected after detailed temporomandibular joint examination. Restricted mouth opening was successfully treated by bilateral intraoral coronoidotomy with additional physiotherapy. The aim of this case report were emphasizing the mandibular coronoid process elongations as an unignorable differential diagnosis of the asymtomatic mandibular hypomobility cases additionally to the temporomandibular joint and masticator muscles dysfunctions and were describing its successful treatment by intraoral surgery and physiotherapy.

The effect of methotrexate on the bone healing of mandibular condylar process fracture: An experimental study in rats

BackgroundMethotrexate (MTX) is an anti-metabolite used in rheumatology and oncology. High doses are indicated for oncological treatment, whereas low doses are indicated for chronic inflammatory diseases. This study evaluated the effect of two MTX treatment schedules on the bone healing of the temporomandibular joint fracture in rats. MethodsSeventy-five adult male Wistar rats were used to generate an experimental unilateral medially rotated condylar fracture model that allows an evaluation of bone healing and the articular structures. The animals were subdivided into three groups that each received one of the following treatments intraperitoneally: saline (1 mL/week), low-dose MTX (3 mg/kg/week) and high-dose MTX (30 mg/kg). The histological study comprised fracture site and temporomandibular joint evaluations and bone neoformation was evaluated by histomorphometric analysis. A biochemical parameter of bone formation was also assessed. ResultsWhen compared with saline, high-dose MTX delayed bone fracture repairs. In this latter group, after 90 days, the histological analysis revealed atrophy of the fibrocartilage and the presence of fibrous tissue in the joint space. The histomorphometric analysis revealed diminished bone neoformation. The alkaline phosphatase levels also decreased after MTX treatment. ConclusionIt was concluded that high-dose MTX impaired mandibular condyle repair and induced degenerative articular changes.

Three Cases of Elongated Mandibular Coronoid Process with Different Presentations

Abnormal elongation of the mandibular coronoid process is rare and its etiology is not yet elucidated. The aim of this report is to demonstrate and discuss the relationship between elongated mandibular coronoid process and limitation of mouth opening with cone beam computed tomography. Although the clinical characteristic of elongation of the coronoid process is mandibular limitation, in this report, one case had problem with mouth opening. Axial scans revealed that the distance between the coronoid process and the inner face of the frontal part of the zygomatic bone may cause limitation in mouth opening. In conclusion, instead of the length, the distance between the coronoid process and the inner face of the frontal part of the zygomatic bone may be the actual reason for limitation of mouth opening. This may prevent misdiagnosis.

Quantitative evaluation of alveolar cortical bone density in adults with different vertical facial types using cone-beam computed tomography

ObjectiveThe purpose of this study was to quantitatively evaluate the cortical bone densities of the maxillary and mandibular alveolar processes in adults with different vertical facial types using cone-beam computed tomography (CBCT) images.MethodsCBCT images (n = 142) of adult patients (20-45 years) were classified into hypodivergent, normodivergent, and hyperdivergent groups on the basis of linear and angular S-N/Go-Me measurements. The cortical bone densities (in Hounsfield units) at maxillary and mandibular interdental sites from the distal aspect of the canine to the mesial aspect of the second molar were measured on the images.ResultsOn the maxillary buccal side, female subjects in the hyperdivergent group showed significantly decreased bone density, while in the posterior region, male subjects in the hyperdivergent group displayed significantly decreased bone density when compared with corresponding subjects in the other groups (p<0.001). Furthermore, the subjects in the hyperdivergent group had significantly lower bone densities on the mandibular buccal side than hypodivergent subjects. The maxillary palatal bone density did not differ significantly among groups, but female subjects showed significantly denser palatal cortical bone. No significant difference in bone density was found between the palatal and buccal sides in the maxillary premolar region. Overall, the palatal cortical bone was denser anteriorly and buccal cortical bone was denser posteriorly.ConclusionAdults with the hyperdivergent facial type tend to have less-dense buccal cortical bone in the maxillary and mandibular alveolar processes. Clinicians should be aware of the variability of cortical bone densities at mini-implant placement sites.

Macrostomia: a review of evolution of surgical techniques.

Macrostomia is a congenital deformity resulting from failure of fusion of maxillary and mandibular process. It is a rare congenital deformity with an incidence of 1 in 60,000 to 1 in 300,000 live births. Transverse facial clefts are more common on right side of face in unilateral cases. Males are more affected than females. Various surgical techniques have been described in the literature for the correction of these defects. We report a case of macrostomia corrected with Z-plasty closure for skin, overlapping muscle closure, and triangular mucosal flap for commissure, with a review on existing techniques.

Facial Clefts and Facial Dysplasia

Most craniofacial malformations are identified by their appearance. The majority of the classification systems are mainly clinical or anatomical, not related to the different levels of development of the malformation, and underlying pathology is usually not taken into consideration. In 1976, Tessier first emphasized the relationship between soft tissues and the underlying bone stating that "a fissure of the soft tissue corresponds, as a general rule, with a cleft of the bony structure". He introduced a cleft numbering system around the orbit from 0 to 14 depending on its relationship to the zero line (ie, the vertical midline cleft of the face). The classification, easy to understand, became widely accepted because the recording of the malformations was simple and communication between observers facilitated. It represented a great breakthrough in identifying craniofacial malformations, named clefts by him. In the present paper, the embryological-based classification of craniofacial malformations, proposed in 1983 and in 1990 by us, has been revisited. Its aim was to clarify some unanswered questions regarding apparently atypical or bizarre anomalies and to establish as much as possible the moment when this event occurred. In our opinion, this classification system may well integrate the one proposed by Tessier and tries at the same time to find a correlation between clinical observation and morphogenesis.Terminology is important. The overused term cleft should be reserved to true clefts only, developed from disturbances in the union of the embryonic facial processes, between the lateronasal and maxillary process (or oro-naso-ocular cleft); between the medionasal and maxillary process (or cleft of the lip); between the maxillary processes (or cleft of the palate); and between the maxillary and mandibular process (or macrostomia).For the other types of defects, derived from alteration of bone production centers, the word dysplasia should be used instead. Facial dysplasias have been ranged in a helix form and named after the site of the developmental arrest. Thus, an internasal, nasal, nasomaxillary, maxillary and malar dysplasia, depending on the involved area, have been identified.The classification may provide a useful guide in better understanding the morphogenesis of rare craniofacial malformations.

Repair for congenital macrostomia: vermilion square flap method.

Transverse facial clefts (macrostomia) are rare disorders that result when the embryonic mandibular and maxillary processes of the first branchial arch fail to fuse due to failure of mesodermal migration and merging to obliterate the embryonic grooves between the maxillary and mandibular processes to form the angle of the mouth at its normal anatomic position. Macrostomia may be seen alone or in association with other anomalies. It may be unilateral, extending along a line from the commissure to the tragus or bilateral. It is usually partial but rarely complete. Transverse facial clefts are more common in males and more common on the left side when unilateral. The goal of macrostomia reconstruction is to achieve functional, symmetrical, and accurate oral commissure with minimal scar. In this paper, we present a six-year-old girl with unilateral macrostomia with preauricular skin tags and malformation of pinna on ipsilateral side treated with vermillion-square flap method. The scar is placed at the upper lip. At two-month followup, the oral commissures are symmetric, the scars are inconspicuous, and the overall balance of facial contour and lip is excellent. We recommend this method for patients with mild to moderate macrostomia.

Odontogenic inflammatory processes of head and neck in computed tomography examinations.

SummaryBackgroundInfections of odontogenic origin are the most common cause of inflammatory disease of head and neck region. Computed tomography allows for defining localization and extent of inflammatory lesions, visualizes soft tissue involvement, presence of an abscess or an osteolytic lesion around causative tooth.The aim of this study was to assess pathways, by which odontogenic infections spread into respective deep head and neck structures in computed tomography examination, taking into account the following criteria: frequency of involvement of respective deep cervical spaces, possibility to determine a probable causative tooth and concordance with the results of clinical examination.Material/MethodsThirty-eight patients cervicofacial inflammatory disease had undergone CT examination of head and neck region with a 64-slice CT scanner after intravenous contrast administration.ResultsAbscess was reported in 30 (79%) cases, while inflammatory infiltration was diagnosed in remaining 8 (21%) patients. There was full concordance between radiological report and intraoperative report In 33 cases (87%). The most commonly involved cervical space was masticator space – 31 patients (82%), followed by submandibular space – 27 patients (71%). Dental examination was impossible in 29 patient because of trismus. During analysis of CT studies we evaluated maxillary and mandibular alveolar processes for presence of osteolytic bone lesions around causative teeth roots and we found them in 30 cases (79%). In 32 cases (84%) cervicofacial infection were of mandibular odontogenic origin.ConclusionsIn most cases CT study in patients suspected of odontogenic craniofacial infection revealed presence of an abscess, needing urgent surgery. Inflammatory infiltration of dental origin most frequently involves masticator space, followed by submandibular space. In most cases CT scanning allows for identification of causative teeth, especially when trismus makes detailed clinical examination impossible.

Anatomical Study of Various Shapes of Mandibular Coronoid Process in Relation to Gender &amp;Age

The Coronoid process is the anterior bony projected part of ramus of mandible giving attachment to two important muscles of mastication. The aim of our study was to observe the gender wise and age wise variation in the shape of coronoid process. The material for this study comprised of 92 (184 sides) dry human mandibles from the osteology bank of Anatomy Department , S.C.B Medical College ,Cuttack . The age and sex differentiating criteria were detailed in materials and methods.Three variants of coronoid process were evident with triangular being the highest 46.73%, rounded 35.3% and hook 17.93%. The incidence of triangular coronoid process predominates in adults and old age of either sex. Rounded was the highest in young and second highest in adult and old of either sex. The hook shaped coronoid process was more in males and older age but absent in younger age group. This comparative study will be beneficial for the Anthropologists, Forensic scientists and Reconstructive surgeons. As far as our knowledge goes this is the frontier study in the Eastern Indian Population.

Structural modifications of the mandibular condylar process as one of the sequels of traumatism in infancy

Context: Mandible and condylar process fractures are well and plentifully described in dental bibliography with the exception of greenstick fractures of the condylar process, which are rarely included. Aims: To compare laminographies and DICOM (Digital Imaging and Communications in Medicine) images of the mandibular condylar axis in patients that suffer blows to the chin with the same type of images of the mandibular condylar axis in patients with other pathologies that did not suffer blows to the chin. Settings and Design: A population of 55 patients who suffered blows in the chin was compared with a control population of 20 patients without historic reference of traumatism in that part of the mandible. The study included 28 Caucasian adult patients, 18 females and 10 males, age range from 22 to 43 years old and 27 Latin patients, 17 females and 10 males, age range from 22 to 43 years old. The control group included 12 Caucasian adult patients, seven females and five males, age range from 22 to 43 years old and eight Latin patients, five females and three males, age range from 22 to 43 years old. Materials and Methods: These patients were studied by images obtained by laminographies with the mouth open and in maximal occlusion and volumetric studies by DICOM method. DICOM is a standard for handling, storing, printing, and transmitting information in medical imaging. It includes a file format definition and a network communications protocol. The communication protocol is an application protocol that uses transmission control protocol (TCP)/internet protocol suite (IP) to communicate between systems. TCP is one of the core protocols of the IP and is so common that the entire suite is often called TCP/IP . Statistical Analysis Used: Student's t -test. Results: This deflection of the condylar axis was not observed in patients with other pathologies that did not suffer blows to the chin region. Conclusions: These fractures provoke deformation of the mandibular condyle, which in turn creates a morphofunctional dysfunction of the Temporomandibular joint (TMJ). It is important to know that this type of fracture can produce growth disturbances.

Management of Malocclusion and Facial Asymmetry Secondary to Fractures of the Mandibular Condyle Process

Most condylar process fractures can be managed conservatively with satisfactory outcome. However, unsuccessful treatment can result in malocclusion and facial asymmetry. We report our experience in surgical management of malunited condylar process fractures. This is a retrospective review of clinical records, photographs, imaging, and dental models of 12 consecutive patients who presented with malocclusion and facial asymmetry after nonoperative or failed treatment of condylar process fractures. Eight patients who presented relatively early (<6 months) after the initial trauma were treated with subcondylar osteotomy (SCO), whereas 4 patients who presented relatively late (>18 months) were treated with sagittal split osteotomy (SSO). These 2 groups were compared in terms of 3 parameters, namely, maximum mouth opening, aesthetic improvement, and patient satisfaction. The 2 groups were statistically similar in all 3 parameters, with the SCO group trending toward higher scores in all 3 parameters. The mean increase in maximal mouth opening in the SCO group was 21 versus 2.5 mm in the SSO group. Subcondylar osteotomy, performed at a relatively early time point, is at least as effective, if not more effective, than traditional SSO in the treatment of subcondylar malunions. Given this finding, a lower threshold should be adopted for the primary treatment of acute subcondylar fractures with open reduction and internal fixation, especially those with moderate displacement that may be at high risk for malunion.

Coronoid-condylar index in assessing of mandibular coronoid hyperplasia. Preliminary results

The purpose of this study was to define the coronoid-condylar index (CCI). The material for studies comprised 26 patients. Thirteen patients were treated for bilateral coronoid hyperplasia. The remaining 13 patients were included in the control group. Based on 3D CT measurements, the coronoidcondylar index (CCI) was calculated and assessed statistically. In patients with coronoid hyperplasia mean CCI was 1.25, while in the control group it was 1.00. The proposed CCI can be used for the evaluation of anomalies of the mandibular coronoid processes.

A Novel Technique for Preventing Skin Pressure Sores Using a Rubber Tube During Surgical Treatment of Mandibular Condyle Fractures

Craniofacial surgery occasionally results in sores and necrosis of the facial skin because of pressure from surgical instruments. During surgical treatment of mandibular condylar process fractures, the main mandibular fragment is routinely retracted downward using a wire to achieve a satisfactory anatomic reduction. This procedure may injure the facial skin. This potential complication is easily overlooked by medical staff, but it is easily preventable. We herein describe a method of using a rubber tube to avoid causing pressure sores of the facial skin during surgical treatment of mandibular condylar process fractures.

The impact of spur therapy in dentoalveolar open bite

Abstract Aim: A longitudinal case-control study, designed to analyse the isolated effect of attached palatal spurs in patients displaying a dentoalveolar anterior open bite, is presented. Methods: Thirty-one patients (mean age of 13.3 years ± 3.17 years) underwent a standardised treatment protocol with fixed anterior spurs for 8.3 months. Lateral cephalograms and plaster casts were analysed before (T1) and after spur therapy (T2). The data were tested using paired t-tests with a significance level of p &lt; 0.05. Results: The cephalometric analysis showed significant elongation of the height of the maxillary (mean +1.22 mm) and the mandibular (mean +1.39 mm) alveolar processes, as well as uprighting of the lower anterior teeth. The plaster cast analysis showed an increase in maxillary intermolar width (mean +0.98 mm) and a decrease in intercanine distance (mean -0.96 mm). The mandibular anterior width and dental arch length reduced. Overall, spur therapy resulted in a significant increase in overjet and overbite. Conclusion: The use of spurs produced a resolution of the open bite in all patients. Therefore, spurs could be considered an effective mechanism for the management of anterior open bite in selected adolescent patients.

Facial development disorders due to inhibition to endochondral ossification of mandibular condyle process caused by malnutrition

To analyze the effect of protein restriction on histomorphometric parameters of bone remodeling in mandibular condyle process and its possible influence in facial development in growing rats. Wistar rats weaned at the age of 21 days were assigned to one of the following groups: control (fed a regular hard diet ad libitum) and protein restricted (PR) (fed a hard diet lacking in protein ad libitum). The animals were euthanized on day 35 after the onset of the experiment. Mandibles were resected, fixed in 10% formalin, hemisected at the symphysis, and then radiographed in order to perform cephalometric studies of the condylar process length and the height of the lower alveolar process. Mandibles were then processed for light microscopy, and histomorphometric determinations were performed on histologic sections of the condylar process subchondral bone. The PR group showed a significantly lower body weight than control group at the end of the experiment. The length of the condylar process was lower in the PR group; however, the diet used in this study did not affect the height of the lower alveolar process. The histomorphometric analysis showed that the PR group exhibited a statistically significant decrease in bone formation and bone volume in condylar process subchondral bone. Protein restriction inhibits bone formation and longitudinal growth in the mandibular condylar process. This result suggest that protein restriction can alter normal facial development.

Assessment of Dentoalveolar Compensation in Subjects with Vertical Skeletal Dysplasia: A Retrospective Cephalometric Study

Objective: This study was aimed at understanding the differences in dentoskeletal parameters in short face and long face individuals and to evaluate the factors governing overbite. Materials and methods: Pretreatment lateral cephalograms of 80 individuals were traced and analyzed. The sample was divided into four groups: —short face male, short face female, long face male and long face female. The descriptive data for all the groups were obtained. Student’s t-test (unpaired) was used to compare the dentoskeletal parameters of the groups and correlation analysis was used to study the factors governing overbite. Results: In this study, it was found that there were highly significant differences in the dentoskeletal parameters among the short face and long face groups. It was also revealed that not all short faces had deep bite and, similarly, not all long faces had open bite. Conclusion: Overbite was governed by a multitude of factors. In the long face group, the major factors governing overbite were lower anterior facial height and the height of anterior mandibular alveolar process. On the contrary, in the short face group, ANB angle and overjet were the governing factors. This study further highlights the interaction between the vertical and sagittal component of malocclusion.