Low condylectomy as the sole treatment for active condylar hyperplasia: facial, occlusal and skeletal changes. An observational study

Abstract

The purpose of this study was to measure the changes in facial, occlusal, and skeletal relationships in patients with active unilateral condylar hyperplasia whose sole treatment was a low condylectomy. A retrospective observational descriptive study was conducted. All patients had undergone a low condylectomy as the sole or initial surgical treatment. The size of the condylar segment removed was decided by matching the affected side with the healthy side, leaving them both like the healthy one. The length of the ramus was measured using panoramic X-ray (distance from the highest part of the condyle to the mandibular angle). Facial, occlusal, and skeletal changes were evaluated using clinical, photographic, and radiological records before and after surgery. Condylectomy as the sole treatment for patients with active condylar hyperplasia allowed improvements to the alterations produced by this pathology, such as chin deviation, tilted lip commissure plane, tilted occlusal plane, angle of facial convexity, unevenness of the mandibular angles, and length of the mandibular ramus. The occlusal relationship also improved with orthodontic and elastic therapy. To conclude, low condylectomy as a sole and aetiological treatment for patients with active condylar hyperplasia allowed improvements to alterations produced by this pathology.

Condylar hyperplasia is a progressive, non-neoplastic overgrowth of the condylar head and neck. The aetiology is not completely clear, and extrinsic as well as intrinsic factors may be behind some of its causes. Intrinsic factors include alterations of condylar vascularization, hormone disorders, and cartilaginous exostosis. Extrinsic factors include micro-trauma and infections. This overgrowth can cause different degrees of facial asymmetry. There are multiple ways of classifying this pathology. Obwegeser and Makek classified condylar hyperplasia into three categories: hemimandibular hyperplasia (HH), hemimandibular elongation (HE), and a combination of the two (HH/HE). The classification of Nitzan et al. is based on the clinical features described by Obwegeser, but is determined mainly by the vector of mandibular asymmetry : condylar hyperplasia with a vertical pattern, condylar hyperplasia with a transverse pattern, and condylar hyperplasia with a mixed pattern.

Frontal and side view photographic records are required for an adequate examination. Several X-ray projections are used for asymmetry studies. A cephalometric analysis of the lateral skull projection allows vertical and sagittal problems to be evaluated. Frontal X-ray and orthopantomograms reveal a tilted occlusal plane and allow the length of both mandibular rami to be compared.

To ensure the diagnosis of condylar hyperplasia, bone scintigraphy is necessary. Bone scintigraphy or SPECT (single photon emission computed tomography) with technetium-99m methylene diphosphonate (99m-Tc-MDP) determines the degree of bone metabolism. A difference of 10% in SPECT between the two condyles, in addition to a medical history of progressive asymmetry and one condyle longer than the other, allows one to diagnose an active condylar hyperplasia. This is the common way to evaluate condylar growth activity.

The level of activity of the affected condyle must be quantified in order to determine an appropriate treatment plan. When the growth rate is greater than 10%, a condylectomy is the option to prevent secondary adaptive deformations. The goal of the condylectomy is to remove the overgrowing cartilage. For its part, orthognathic surgery may be considered an option only in cases where the condylar growth has ceased, with the sole objective of correcting the asymmetry. Condylectomy and orthognathic surgery can be performed simultaneously.

Different treatment protocols have been proposed for this pathology. However, there are no clinical, radiographic, or occlusal studies that can ensure the proposed treatment is the right one. Based on the statement that all treatments ought to solve the cause of the problem, we understand that any surgical indication should contemplate the removal of the hyperplasic condylar cartilage. We pose the following question: Can a low condylectomy (removing the entire excess segment of the condyle, thus attaining balance between the healthy and the affected side) on its own resolve facial, occlusal, and skeletal alterations caused by condylar hyperplasia in the three-dimensional planes?

The purpose of this study was to measure the changes in facial, occlusal, and skeletal relationships in patients with active unilateral condylar hyperplasia whose sole treatment was a low condylectomy.

Materials and methods

A retrospective observational descriptive study was conducted. The study group was comprised entirely of patients with active unilateral condylar hyperplasia seen at the study institutions between the years 2000 and 2010. Medical charts were reviewed. The study was conducted with ethics board approval.

Inclusion criteria were the following: (1) Diagnosed active unilateral condylar hyperplasia, confirmed by a full clinical, radiographic, and scintigraphy study. The clinical evaluation for diagnosis of condylar hyperplasia was progressive mandibular deviation with occlusal changes, as well as a cross-bite of the contralateral side or an ipsilateral open bite. The radiographic characteristics compatible with condylar hyperplasia were a lengthened condyle/ramus. The amount of radiopharmaceutical intake in SPECT should exceed 55% in the affected side or exceed a difference of 10% between the two sides. (2) Orthodontic braces used, but teeth not necessarily aligned or in good occlusion when casts are in an advantageous position. (3) Condylectomy as the sole or initial surgical treatment.

Exclusion criteria were any facial asymmetry due to any cause other than condylar hyperplasia, and patients treated with orthognathic surgery at the same time as condylectomy.

Surgical and postsurgical procedures

With regard to the surgical procedure, the temporomandibular joint is exposed through a pre-auricular or endaural access. The inferior joint space is then revealed, providing a full view of the condylar head. The condylar excess is removed with a burr. The size of the condylar segment removed is determined by matching the affected side with the healthy side, leaving them both like the healthy one. We call this procedure a ‘proportional low condylectomy’. The length of the ramus is measured using a panoramic X-ray (distance from the highest part of the condyle to the mandibular angle). The disc is preserved.

The goal of a low condylectomy is to eliminate the cause of the mandibular asymmetry while simultaneously leaving the length of the affected side (from the highest part of the condyle to the mandibular angle) the same length as the healthy side. The same surgeon performed all of these surgeries (R.F.).

All patients underwent physiotherapy and intermaxillary elastic therapy from 1 to 3 months postsurgery, under the supervision of the surgeon. Physiotherapy was performed with ipsilateral and contralateral jaw movements, which started the day after surgery and were done three times a day for 1 month. Intermaxillary elastic therapy was applied 15 days after surgery (a heavy elastic band was attached from the upper bicuspid and upper canine to the lower bicuspid and lower canine). The objective of elastic therapy is to guide the jaw into a proper position (to align the inferior dental midline with the facial midline), achieving a centred chin and proper occlusion and avoiding an open bite. This elastic therapy lasted 3 months.

Data collection

Each patient underwent a complete clinical examination before surgery (frontal and in-profile photographs), a radiographic examination (frontal and panoramic X-rays), and scintigraphy (SPECT). All clinical and radiographic examinations were repeated 15–24 months after surgery.

For each patient we recorded the following data: age, gender, affected condyle, SPECT uptake percentage, size of the removed condylar segment, clinical and radiographic control after surgery, and total follow-up time ( Table 1 ).

Table 1
Patient distribution according to age, gender, affected side, SPECT percentages, length of condyle removed, further surgery, clinical control, and total follow-up.
Patient Age, years Male Female Right condyle Left condyle % SPECT affected condyle % SPECT healthy condyle Length removed, mm Further orthognathic procedure Clinical and X-ray control (months) Total follow-up (months)
1 25 X X 61 39 10 15 55
2 15 X X 56 44 8 15 42
3 16 X X 69 31 6 18 36
4 19 X X 56 44 7 Bimaxillary osteotomy 20 69
5 20 X X 67 33 10 15 91
6 14 X X 64 36 7 24 41
7 20 X X 56 44 12 15 67
8 14 X X 63 37 9 18 41
79 21 X X 58 42 10 Le Fort I 16 95
10 15 X X 62 38 8 18 120
11 17 X X 60 40 10 15 107
12 20 X X 58 42 15 15 100
13 33 X X 64 36 9 17 84
14 19 X X 65 35 10 16 15
15 21 X X 57 43 10 15 15
16 17 X X 58 42 5 15 18
Total 6 10 10 6 2

SPECT, single photon emission computerized tomography.

Clinical evaluation

The clinical evaluation was done using the clinical frontal and profile photographs that were standardized with a digital grid.

To assess chin deviation, the centricity of the chin was measured in degrees by determining the angle between the facial midline and the straight line connecting the chin with the facial midline on a frontal facial photograph ( Fig. 1 ).

Fig. 1
Frontal photograph showing chin deviation and tilted lip commissure plane. Left: prior to surgery; right: postsurgery.

To assess the tilted lip commissure plane, the difference in distance between a horizontal line drawn from each pupil (bipupillary line) to each commissure was determined ( Fig. 1 ).

The angle of facial convexity of the affected side was assessed by evaluation of the anteroposterior position of the soft tissue pogonion, determined by the intersection of straight lines between the glabella–subnasale point and the subnasale–pogonion point in a profile view facial photograph ( Fig. 2 ).

Fig. 2
Profile facial photograph showing the angle of facial convexity (glabella–subnasale–pogonion angle). Left: prior to surgery; right: postsurgery.

The occlusal relationship was assessed as follows ( Fig. 3 ): (1) Molar transverse relationship on the contralateral side, rated as normal or cross-bite. (2) Overjet and overbite, rated as positive, zero, or negative. (3) Deviation from the dental midlines, rated as deviated or centred.

Fig. 3
Occlusal relationship: (A) prior to surgery; (B) 1 day after surgery; (C) 1 month after surgery; (D) 10 years after surgery.

Radiographic evaluation

The radiographic evaluation was done using frontal and panoramic X-rays.

The deviation of the chin was measured in degrees from the angle formed by the skeletal midline (vertical line in the middle of the base of the crista galli) and the straight line that connects the centre of the chin to the skeletal midline on the frontal X-ray ( Fig. 4 ).

Fig. 4
Frontal cephalometry. Distance between the mandibular angle and the bizygomatic line, measured in millimetres; measurement of the occlusal plane in relation to the bizygomatic line, and the chin in relation to the skeletal medial line, measured in degrees. Left: prior to surgery; right: postsurgery.

Unevenness of the mandibular angle was determined by measuring the distance between the pregonial notch on each side and the true horizontal line connecting both fronto-malar sutures on the frontal X-ray ( Fig. 4 ).

The tilted occlusal plane angle was measured between the occlusal plane (the straight line that connects the highest point of the distal cuspid of the lower second molar teeth) and the horizontal line at the height of the distal cuspid of the second molar tooth on the affected side on the frontal X-ray ( Fig. 4 ).

The length of the mandibular ramus was determined by measuring the distance in millimetres between the highest condylar point and the gonial angle (total ramus height, including the condyle) on the panoramic X-ray ( Fig. 5 ).

Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Low condylectomy as the sole treatment for active condylar hyperplasia: facial, occlusal and skeletal changes. An observational study
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