Treatment of Mandibular Prognathism

Abstract

Mandibular prognathism (MP) or skeletal Class III malocclusion with a prognathic mandible is one of the most severe maxillofacial deformities. Facial growth modification can be an effective method of resolving skeletal Class III jaw discrepancies in growing children with dentofacial orthopedic appliances including the chincup, face mask, maxillary protraction combined with chincup traction and the Fränkel functional regulator III appliance. Orthognathic surgery in conjunction with orthodontic treatment is required for the correction of adult MP. The two most commonly applied surgical procedures to correct MP are sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy. Both procedures are suitable for patients in whom a desirable occlusal relationship can be obtained with a setback of the mandible, and each has its own advantages and disadvantages. In bilateral SSRO, the intentional ostectomy of the posterior part of the distal segment can offer long-term positioned stability. This may be attributable to reduction of tension in the pterygomasseteric sling that applies force in the posterior mandible. While various environmental factors have been found to contribute to the development of MP, heredity plays a substantial role. The relative contributions of genetic and environmental components in the etiology of MP are unclear. The recent identification of the genetic susceptibilities to MP constitutes the first step toward understanding the molecular pathogenesis of MP. Further studies in molecular biology are needed to identify the gene-environment interactions associated with the phenotypic diversity of MP and the heterogenic developmental mechanisms thought to be responsible for them.

Relationship between P561T and C422F polymorphisms in growth hormone receptor gene and mandibular prognathism

“…20,22,23 Although a number of etiological factors have been found to contribute to mandibular morphology, genetic factors play a significant role. 33 Bailey 34 found that 30 genes can affect the morphogenesis of the mandible in mice. Different sites of GHR and new candidate genes must be examined to explain the relationship between different phenotypes and genetic variants as well as to understand the effects of genetic factors in the multifactorial etiology of MP.…”

Assessment of skeletal stability of intraoral vertical ramus osteotomy with one-day maxillary–mandibular fixation followed by early jaw exercise

“…Sagittal split ramus osteotomy (SSRO) and intraoral vertical osteotomy (IVRO) are common strategies for the treatment of mandibular prognathism patients (Chang et al, 2000). Both surgical techniques are well established, and each has risks and benefits.…”

Effect of bone quality and position of the inferior alveolar nerve canal in continuous, long-term, neurosensory disturbance after sagittal split ramus osteotomy

“…In treating prognathism, surgeons, including dentists, strive to restore oral and maxillofacial function and aesthetics (Chang et al, 2006). Complications such as neurosensory disturbance (NSD) in the teeth, gingiva, lips, and cheeks may occur after surgical procedures such as sagittal split ramus osteotomy (SSRO) (van Merkesteyn et al, 2007;Yoshioka et al, 2010) because of injury to the inferior alveolar nerve (IFAN).…”