Jaw Malocclusion Research Articles

Synonymous alterations of cancer-associated Trp53 CpG mutational hotspots cause fatal developmental jaw malocclusions but no tumors in knock-in mice.

Intragenic CpG dinucleotides are tightly conserved in evolution yet are also vulnerable to methylation-dependent mutation, raising the question as to why these functionally critical sites have not been deselected by more stable coding sequences. We previously showed in cell lines that altered exonic CpG methylation can modify promoter start sites, and hence protein isoform expression, for the human TP53 tumor suppressor gene. Here we extend this work to the in vivo setting by testing whether synonymous germline modifications of exonic CpG sites affect murine development, fertility, longevity, or cancer incidence. We substituted the DNA-binding exons 5-8 of Trp53, the mouse ortholog of human TP53, with variant-CpG (either CpG-depleted or -enriched) sequences predicted to encode the normal p53 amino acid sequence; a control construct was also created in which all non-CpG sites were synonymously substituted. Homozygous Trp53-null mice were the only genotype to develop tumors. Mice with variant-CpG Trp53 sequences remained tumor-free, but were uniquely prone to dental anomalies causing jaw malocclusion (p < .0001). Since the latter phenotype also characterises murine Rett syndrome due to dysfunction of the trans-repressive MeCP2 methyl-CpG-binding protein, we hypothesise that CpG sites may exert non-coding phenotypic effects via pre-translational cis-interactions of 5-methylcytosine with methyl-binding proteins which regulate mRNA transcript initiation, expression or splicing, although direct effects on mRNA structure or translation are also possible.

Incidental findings involving the temporomandibular joint on computed tomography and magnetic resonance imaging.

The temporomandibular joint (TMJ) is frequently imaged in head and neck computed tomography (CT) and magnetic resonance imaging (MRI) studies. Depending on the indication for the study, an abnormality of the TMJ may be an incidental finding. These findings encompass both intra- and extra-articular disorders. They may also be related to local, regional or systemic conditions. Familiarity with these findings along with pertinent clinical information helps narrow the list of differential diagnoses. While definitive diagnosis may not be immediately apparent, a systematic approach contributes to improved discussions between clinicians and radiologists and better patient management.

Assessment and Comparison of Temporomandibular Joint for Occurrence and Severity of Disorders in Adult Cases with Unilateral Cleft Lip and Palate and Non-cleft Class I: An Observational Study

Background: Cleft Lip and Palate (CLP) are hereditary deformity of craniofacial structure. Temporomandibular disorder has number of clinical problems affecting muscles of mastication and its associated structures. There are several methods used to evaluate temporomandibular dysfunction (MRI, etc), Helkimo index is a settler in advancing indices, other indices used are CMI, MFIQ, FONSECA. The design of the following study was to evaluate the TMJ disorders in UCLP, if any, and compare with the non-cleft cases.&#x0D; Methodology: Total 30 patients aged 16 to 20 years, will be selected from the patients coming to smile train Out Patient Department (OPD) of Orthodontics and Dentofacial Orthopaedics, Wardha. The total cases will be divided into two groups: a) Group I - unliteral cleft lip and palate cases b) Group II - non cleft class I cases Digital records of the patient (lateral cephalogram, photograph, models) will be taken and stored. Helkimo, MFIQ, CMI, Fonseca will be recorded on all patients participated in study. The Helkimo index will be taken to assess the presence and severity and MFIQ index will be taken to assess mandibular functioning in cleft cases based on the questionnaire.&#x0D; Expected Results: The dental apparatus (interdental relation of maxillary and mandibular dentition) plays an important role in the temporomandibular joint's well-being. Trauma due to the occlusal instability has definite effect on the TMJ in long run. Cleft is always associated with inter jaw malocclusion and therefore TMDs in the cleft patient is thought to occur. The treatment protocol for grown cases with severe skeletal malocclusion is orthognathic surgery. The TMJ correction remains untouched. It can be expected that altered TMJ anatomy can lead to TMDs in cleft lip and palate cases.&#x0D; Conclusion: To convey the occurrence of TMDs in cleft due to the inter jaw malocclusion and its early treatment approach for TMJ deprogramming along with dental and surgical correction in CLP.

Novel Modifications to Total Maxillary Swing Approach in Extensive Nasopharyngeal Angiofibroma to Minimize Complications.

Maxillary swing approaches provide excellent exposure of the anterior, mid, and anterolateral skull base offering a wide window to approach nasopharyngeal neoplasms; however, they are also associated with complications. The present study aimed to evaluate the results of a modified total maxillary swing (TMS) approach developed to minimize postoperative complications. The modified TMS approach was used to treat five patients who had extensive juvenile nasopharyngeal angiofibromas between March and October 2019 at our tertiary care center. Surgical technique, preoperative image findings, and intra-operative findings were recorded. In the postoperative follow-up, patients were examined to rule out all possible complications associated with the procedure according to the literature. A retrospective analysis was performed to assess tumor extensions, surgical modifications, and postoperative complications. All tumors had orbital and infratemporal (lateral limit) involvement while four had intracranial involvement. No per-operative complications were reported, and postoperative clinical and endoscopic evaluation was performed at 1, 2, and 3months. There was no evidence of complications including residue, recurrence, maxillary necrosis, ophthalmoplegia, epiphora, palatal fistula, or jaw malocclusion. Besides, minor complications such as infraorbital margin skin retraction, infraorbital serous collection, maxillo-zygomatic abscess, and unsightly scar were also not seen. Only one case presented with maxillary osteomyelitis which was resolved with mini-plate removal and antibiotics. A modified TMS approach is a prudent option to ensure complete removal of juvenile nasopharyngeal angiofibromas with negligible complications.

Perioperative consideration of general anesthesia for acromegalic patients.

Perioperative consideration of general anesthesia for acromegalic patients.

High Le Fort I and Bilateral Split Sagittal Osteotomy in Crouzon Syndrome

Crouzon syndrome is a rare, autosomal dominant disease from a fibroblast growth factor receptor 2 gene mutation, characterized by premature craniosynostosis, hypertelorism, orbital proptosis, psittichorina, hypoplastic maxilla, and mandibular prognathism. We present an adult 32-year-old Crouzon syndrome patient who underwent an elective High Le Fort I and bilateral split sagittal osteotomy for midface advancement with a background of jaw malocclusion and obstructive respiratory symptoms. The operation features a potential dynamic movement of the secured airway in the surgical field and close proximity to exposed ocular structures. Permissive hypotensive anesthesia was employed to improve the surgical field and reduce intraoperative blood loss and dose of long-acting opioids. He was extubated at the end of an uneventful surgery and was monitored in the high dependency overnight before he was discharged to the general ward. Perioperative issues include potential difficult airway management; ocular, auditory, and neurological injury prevention; surgery-specific anesthetic technique; and postoperative analgesia. Understanding the multisystemic issues facilitates the dynamic anesthetic management during surgery. Good communication among the multidisciplinary team is essential to ensure a successful operation and uneventful recovery.

Acromegaly

Acromegaly is an acquired disorder related to excessive production of growth hormone (GH) and characterized by progressive somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The prevalence is estimated at 1:140,000–250,000. It is most often diagnosed in middle-aged adults (average age 40 years, men and women equally affected). Due to insidious onset and slow progression, acromegaly is often diagnosed four to more than ten years after its onset. The main clinical features are broadened extremities (hands and feet), widened thickened and stubby fingers, and thickened soft tissue. The facial aspect is characteristic and includes a widened and thickened nose, prominent cheekbones, forehead bulges, thick lips and marked facial lines. The forehead and overlying skin is thickened, sometimes leading to frontal bossing. There is a tendency towards mandibular overgrowth with prognathism, maxillary widening, tooth separation and jaw malocclusion. The disease also has rheumatologic, cardiovascular, respiratory and metabolic consequences which determine its prognosis. In the majority of cases, acromegaly is related to a pituitary adenoma, either purely GH-secreting (60%) or mixed. In very rare cases, acromegaly is due to ectopic secretion of growth-hormone-releasing hormone (GHRH) responsible for pituitary hyperplasia. The clinical diagnosis is confirmed biochemically by an increased serum GH concentration following an oral glucose tolerance test (OGTT) and by detection of increased levels of insulin-like growth factor-I (IGF-I). Assessment of tumor volume and extension is based on imaging studies. Echocardiography and sleep apnea testing are used to determine the clinical impact of acromegaly. Treatment is aimed at correcting (or preventing) tumor compression by excising the disease-causing lesion, and at reducing GH and IGF-I levels to normal values. Transsphenoidal surgery is often the first-line treatment. When surgery fails to correct GH/IGF-I hypersecretion, medical treatment with somatostatin analogs and/or radiotherapy can be used. The GH antagonist (pegvisomant) is used in patients that are resistant to somatostatin analogs. Adequate hormonal disease control is achieved in most cases, allowing a life expectancy similar to that of the general population. However, even if patients are cured or well-controlled, sequelae (joint pain, deformities and altered quality of life) often remain.

Traumatic Temporomandibular Joint Luxation in a Cat and Treatment by Condylar Tethering

SummaryThe cat in this report was admitted with mandibular symphyseal separation and jaw malocclusion referrable to luxation of the right TMJ. Radiographs revealed a fracture of the right articular eminence in the frontal plane of the head. Closed reduction, while initially successful, failed to prevent reluxation of the mandible. Polyester suture was used to successfully tether the right mandibular condyle to the zygomatic process of the temporal bone, preventing any reluxation and allowing healing of the fractured eminence.Temporomandibular joint (TMJ) luxation is a relatively commonly encountered injury of the feline jaw. While most temporomandibular joints remain stable once relocated, some will reluxate. A new technique using polyester suture to successfully treat an unstable rostral TMJ luxation, and associated fracture in a cat, is described. Alternative treatments for this condition are briefly discussed.

Wear of sheep’s teeth

A survey of wear of sheep’s teeth in the Wairarapa district led to detailed investigations of three farms on which sheep showed high, medium, and low rates of wear of incisor teeth. Dental examination of five-year-old ewes showed that mean lengths of incisor teeth were 0.15, 0.35, and 0.55 in. on high-, medium-, and low-wear farms respectively. Breed differences, or malocclusion of jaws, did not appear to be involved. A concurrent paper (Part II—in this issue) suggests that chemical differences in spring pastures are not responsible for the wear differences. Analysis of faeces collected at monthly intervals over 1964–65 showed that their contents of soil were highest on the high-wear farm, lowest on the low-wear farm, and intermediate on the medium-wear farm. Soil was ingested in greatest amounts over the wet cold months when pastures are short and grazing pressure high. Calculated values for ingested soil July-October are probably about 25 lb, 10 lb, and 1 lb for each animal on high-, medium-, a...