Residents’ journal review

Sagittal split osteotomy with and without inferior border osteotomy

Böckmann R, Schön P, Neuking K, Meyns J, Kessler P, Eggeler G. In vitro comparison of the sagittal split osteotomy with and without inferior border osteotomy. J Oral Maxillofac Surg 2015;73:316-23

The introduction of the sagittal split osteotomy (SSO) by Hugo Obwegeser in 1953 marked the dawn of a modern era in orthognathic surgery. The fundamental concept of the SSO is to fracture the mandible by a splitting maneuver to preserve the inferior alveolar nerve. The 2 most common and interrelated complications of the SSO are unfavorable splits and damage to the inferior alveolar nerve. The purpose of this in-vitro study was to determine whether the addition of an inferior border osteotomy to the traditional Obwegeser-Dal Pont SSO resulted in a defined fracture line and a reduction of torque required to fracture the mandible. Seventy formalin-fixed human hemimandibles were fixated in a customized rack and divided into 2 groups; 35 were split with the traditional Obwegeser-Dal Pont SSO and 35 with the modified Obwegeser-Dal Pont SSO with the addition of an inferior border osteotomy. The maximum torque force was recorded, and the fracture pattern was classified for each split. The mean torque forces required to split the mandible were 1.38 and 1.02 Nm in the traditional and modified groups, respectively. Most hemimandibles split with the traditional technique had a splitting pattern along the mandibular canal, whereas most hemimandibles split with the modified inferior border osteotomy fractured more favorably along the posterior border of the ramus and through the mandibular angle. The differences in mean torque force and splitting pattern for the traditional and modified techniques were statistically significant. The addition of an inferior border osteotomy decreased the force necessary to split the mandible and resulted in a more predictable splitting pattern that can cause less damage to the inferior alveolar nerve.

Reviewed by Nathan Wieder

Upper lip inclination in orthodontics and orthognathic surgery

Naini FB, Cobourne MT, McDonald F, Wertheim D. The aesthetic impact of upper lip inclination in orthodontics and orthognathic surgery. Eur J Orthod 2015;37:81-6

The nasolabial angle is a common measurement used to determine facial balance in orthodontic and orthognathic surgery patients. However, it includes 1 aspect of the face that is unaffected by orthodontics—the nose. This article contends that using the upper lip inclination (ULI), which is measured by the angle formed from a line tangent to the upper lip and a horizontal line through subnasale, may be more appropriate. The purpose of the article was to evaluate the ULI on a quantitative basis to determine the perceived attractiveness and its esthetic impact in treatment planning. To do so, the authors used a series of silhouette profiles on which they incrementally altered the ULI and had them rated on a Likert scale by 3 groups of subjects: pretreatment orthognathic patients, laypeople, and clinicians. Also included was a questionnaire in which the subjects could state whether the silhouette profile looked as if it needed orthognathic surgery. The results showed that the most ideal ULI was between 79° and 85°, and that the perceived need for surgery was at a threshold of less than 64° or greater than 91°. The pretreatment orthognathic patients were the most likely of the groups to recommend orthognathic surgery; this showed that they were the most critical. This study focused only on white profiles, whereas future studies could use other ethnic groups and facial types to gain a greater pool of normative data. It would also be interesting to compare a series of silhouettes with identical nasolabial angle values, but differing ULI values and nasal inclinations.

Reviewed by Kirk Bean

Upper lip inclination in orthodontics and orthognathic surgery

Naini FB, Cobourne MT, McDonald F, Wertheim D. The aesthetic impact of upper lip inclination in orthodontics and orthognathic surgery. Eur J Orthod 2015;37:81-6

The nasolabial angle is a common measurement used to determine facial balance in orthodontic and orthognathic surgery patients. However, it includes 1 aspect of the face that is unaffected by orthodontics—the nose. This article contends that using the upper lip inclination (ULI), which is measured by the angle formed from a line tangent to the upper lip and a horizontal line through subnasale, may be more appropriate. The purpose of the article was to evaluate the ULI on a quantitative basis to determine the perceived attractiveness and its esthetic impact in treatment planning. To do so, the authors used a series of silhouette profiles on which they incrementally altered the ULI and had them rated on a Likert scale by 3 groups of subjects: pretreatment orthognathic patients, laypeople, and clinicians. Also included was a questionnaire in which the subjects could state whether the silhouette profile looked as if it needed orthognathic surgery. The results showed that the most ideal ULI was between 79° and 85°, and that the perceived need for surgery was at a threshold of less than 64° or greater than 91°. The pretreatment orthognathic patients were the most likely of the groups to recommend orthognathic surgery; this showed that they were the most critical. This study focused only on white profiles, whereas future studies could use other ethnic groups and facial types to gain a greater pool of normative data. It would also be interesting to compare a series of silhouettes with identical nasolabial angle values, but differing ULI values and nasal inclinations.

Reviewed by Kirk Bean

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Apr 6, 2017 | Posted by in Orthodontics | Comments Off on Residents’ journal review
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