Reduction genioplasty enhances quality of life in female patients with prognathism and maxillary hypoplasia undergoing bimaxillary osteotomy

Abstract

The structure of the chin determines facial attractiveness and is directly linked to quality of life (QoL). In patients with prognathism and maxillary hypoplasia, bimaxillary osteotomy (BIMAX) with mandibular setback does not always lead to a more slender chin or improved aesthetics. The aim of the present study was to evaluate whether QoL differed between females undergoing BIMAX alone (group I; n = 30) and those undergoing BIMAX combined with reduction genioplasty (group II; n = 30). Presurgical and postsurgical evaluations included cephalography, photogrammetry, and the Oral Health Impact Profile with one additional domain (aesthetics). Setback of the hard tissue pogonion was significantly greater ( P = 0.006) in group II (7.1 mm) than in group I (2.7 mm). Only in group II were soft tissue pogonion changes highly significant ( P < 0.001), amounting to a mean of 5 mm. In both groups, the QoL domains ‘social disability’, ‘psychological discomfort’, and ‘dissatisfied with aesthetics’ changed significantly towards lower impact scores. Changes in the latter two domains were significantly greater in group II patients than in group I patients ( P = 0.021; P < 0.001) and were correlated with changes in the soft tissue pogonion in the horizontal ( P = 0.024; P = 0.022) and vertical directions ( P = 0.037; P = 0.042). Genioplasty addresses both psychological and aesthetic concerns, and therefore significantly enhances postsurgical QoL.

Today, aesthetic and functional improvements are the goals of orthognathic surgery and both should be addressed by the medical staff throughout planning. In recent decades, however, orthognathic surgery patients have focused their expectations mostly on the postsurgical facial aesthetic outcome. The desire for aesthetic improvement in these patients tends to overshadow their awareness of the need to correct functional deficits. Among young adults in particular, problems with chewing seem to be less common than problems with facial appearance. Consequently, the quality of life (QoL) benefits are generally high among orthodontic surgery patients if they perceive an aesthetic improvement of the facial features after surgery.

As convexity of the facial profile within a normal range is considered to be most harmonic and attractive, patients with a prognathism and maxillary hypoplasia with a more concave profile are assessed by laypersons to be less attractive and intelligent. Consequently, a bimaxillary osteotomy (BIMAX) is often recommended to produce a more convex profile. However, orthognathic surgery in these cases does not necessarily lead to a more convex and therefore more attractive profile. One reason for this is that, even after advancement of the maxilla, the sagittal discrepancy can be overcome by maxilla movement alone in many cases, resulting in less mandible setback than needed to provide a convex profile. An even more decisive point is that these patients feature not only mandibular prognathism and midface hypoplasia, but also a prominent chin. Therefore, BIMAX alone cannot address all these features to provide a more convex profile. Only additional genioplasty offers the option to reduce the chin region to create more facial convexity.

We previously reported that a reduction of the lower facial third with narrowing of the facial convexity angle within the scope of BIMAX leads to a significant decrease in the QoL impact scores of items covering psychological discomfort. To address these findings and the considerations mentioned above, we changed our strategy for skeletal corrections in patients with prognathism and maxillary hypoplasia from exclusive BIMAX to a combination of BIMAX with genioplasty, aiming to positively impact the QoL.

Therefore, the objective of this study was to elucidate whether a combination of BIMAX and genioplasty for patients with prognathism and maxillary hypoplasia has a greater positive impact on the patient’s QoL than BIMAX alone. These results might affect further surgical treatment strategies for these patients.

Materials and methods

Ethical approval of the study protocol

Approval for the study was given by the Ethics Committee of the Medical Association of the state. All participants were informed about the aims and protocol of the study.

Patients

The retrospective study sample included white Caucasian female patients who were admitted from orthodontists for surgery and who consecutively underwent BIMAX for correction of prognathism and maxillary hypoplasia. Patients were selected using exclusion criteria to avoid any bias. These criteria were patient findings that exceeded routine orthognathic surgery planning, such as those with an anterior open bite greater than 1 cm, facial asymmetry with occlusal cants in the frontal plane, midline deviations and mandibular border asymmetry, matured cleft lip and palate, severe congenital facial or post-traumatic deformity, and obese patients (body mass index (BMI) > 30 kg/m 2 ). In the years 2008 and 2009, 30 patients underwent BIMAX without additional procedures (group I, mean ± standard deviation (SD) age 23.3 ± 4.8 years), and in the years 2010 and 2011, 30 patients underwent BIMAX with genioplasty performed in a single operation due to the change in strategy to include BIMAX and genioplasty in one session (group II; mean ± SD age 23.1 ± 6.8 years). Patients not ready to undergo an additional genioplasty were treated exclusively with BIMAX and were also excluded from the study. Lateral cephalograms and lateral photographs were taken for all subjects, and they completed the Oral Health Impact Profile (OHIP) questionnaire at first presentation 1 month before surgery (mean 1.4 ± 0.8 months) and at a follow-up appointment 6 months after surgery (mean 6.4 ± 1.2 months). Patients wore orthodontic appliances during the entire course of the study.

Hard tissue and soft tissue analysis

Lateral cephalometry

Subjects were positioned in the cephalostat (Orthoceph, Siemens AG, Munich, Germany) and radiographs were obtained in habitual occlusion, with lips in repose and with a metric ruler in front of the midfacial vertical line. Tracings were obtained for all cephalograms. After loading the cephalogram into a personal computer, the ruler was used to size the cephalogram image in the software program (Adobe Photoshop version 7.0; Adobe Systems, San Jose, CA, USA), so that 1 mm on the ruler represented 1 mm of actual scale (life-size) in the software program. The landmarks were identified manually using photographic software. Hard tissue landmarks on the cephalograms were traced using the Cephalometrics for Orthognathic Surgery (COGS) analysis by Burstone et al. ( Fig. 1 ). The horizontal reference line was constructed by raising a line 7° from the sella–nasion, and a line perpendicular to this at the nasion was used as the vertical reference line. The movement of hard tissue and soft tissue landmarks from before surgery to after surgery was measured in millimetres with respect to the horizontal and vertical reference lines.

Fig. 1
Hard tissue landmarks and reference lines for tracing lateral cephalograms. N, nasion; S, sella; A, point A; B, point B; L1, lower incisor; Gn, gnathion; Pg, pogonion; ANS, anterior nasal spine. Cephalometric angles were constructed within the landmarks.

The corresponding cephalometric angles were constructed within the landmarks and measured in degrees in the presurgical and postsurgical cephalograms. Differences were recorded as the surgically induced change.

Lateral (two-dimensional) photogrammetry

Subjects were asked to sit on a chair in front of a pale blue background, maintain a straight back, and look straight ahead with a relaxed facial expression and eyes fully open, lips gently closed, and not smiling (natural head position, NHP). A neck holder was then adjusted to help the subjects fix their NHP. For reproducibility, a simple, indirect light source consisting of four 60 W fluorescent tubes on the ceiling was used to eliminate undesirable shadows from the contours of the facial profile. The subjects’ faces were photographed in the right lateral view, together with a metric scaled ruler in front of the midfacial vertical line (true vertical, TV). A high-resolution digital camera with a flash (Canon 550D, Canon Inc., Tokyo, Japan) was firmly mounted on a photo stand 1 m in front of the subject. All photographs were taken at 2048 × 1536 pixels resolution and saved in JPEG file format. Images were stored on the personal computer’s hard drive and then transferred into the photographic software program. The lateral photographs were adjusted to life-size in the same way as the cephalogram adjustment as described above. Soft tissue landmarks, distances, and angles were traced with the tools of the software using the soft tissue analysis by Legan and Burstone. Additionally, the TV on the nasion and the true horizontal (TH, perpendicular to TV through the tragus) were constructed as reference lines for horizontal and vertical landmark movements. Presurgical and postsurgical distances of each landmark towards the reference lines were measured and differences were recorded as the vertical and horizontal surgical change, respectively ( Figs. 2 and 3 ).

Fig. 2
Soft tissue landmarks and reference lines for tracing lateral photographs. Ls, labrale superius; Li, labrale inferius; Si, labiomental sulcus; Pg′, soft tissue pogonion; Esth, aesthetic line; Trg, tragus point; TV, true vertical; TH, true horizontal.

Fig. 3
Soft-tissue angles and distances for tracing lateral photographs. 1 = facial convexity angle (FCA); 2 = nasolabial angle (NLA); 3 = mentolabial angle (MLA); 4 = upper lip length (ULL); 5 = lower lip length (LLL).

Assessment of quality of life (QoL)

QoL was assessed using questionnaires comprising OHIP-14 items (OH-1 to OH-14) to capture measures of seven domains. These domains include psychological disability, social disability, handicap, physical disability, physical pain, functional limitation, and psychological discomfort. The OHIP-14 was supplemented with one additional domain (ADD) explicitly covering aesthetics ( Table 1 ). In the questionnaires given before surgery, subjects were asked how frequently they were impacted by each measure in the preceding 12 months. After surgery, patients were again asked to fill out the questionnaires with respect to the impact of the operation on QoL during the previous month. Each item was scored on a five-point scale as follows: never, score 0; hardly ever, score 1; occasionally, score 2; fairly often, score 3; very often, score 4. The higher the score, the poorer the QoL. For analysis, mean scores were derived from the scores given to each domain in both of the questionnaires.

Table 1
Domain subscales of the OHIP-14 items and the additional domain (ADD).
Domain Subscale
OHIP item Short description
Psychological disability OH-9 Difficult to relax
Social disability OH-11 Irritable with people
OH-12 Difficulty doing usual jobs
Handicap OH-13 Less satisfying life
Physical disability OH-7 Diet has been unsatisfactory
OH-8 Interrupt meals
OH-14 Totally unable to function
Physical pain OH-3 Painful aching
OH-4 Uncomfortable to eat
Functional limitation OH-1 Trouble pronouncing words
OH-2 Worse sense of taste
Psychological discomfort OH-5 Self conscious
OH-6 Feel tense
OH-10 Feel embarrassed
Dissatisfied with aesthetics ADD Dissatisfied with facial aesthetics

OHIP, Oral Health Impact Profile.

Planning and surgery

BIMAX was planned using cephalometric software (Onyx Ceph version 2.7.19; Image Instruments, Chemnitz, Germany) and a mock operation, as published previously. All operations were performed by one senior surgeon. BIMAX consisted of a Le Fort I osteotomy with maxillary advancement and/or impaction, and a bilateral sagittal split ramus osteotomy was performed for mandibular setback. Patients remained in the hospital for a mean of 5 days after surgery. Postoperatively, patients wore light training elastics for a 2- to 4-week period and were returned to the care of their orthodontists.

In group II patients, a genioplasty was planned using two-dimensional (2D) photogrammetry and photographic software (Adobe Photoshop version 7.0). Before surgery, the extent of the genioplasty was demonstrated and discussed with each patient. A facial convexity angle in a normal range, of approximately 170°, a mentolabial angle of 135°, a lower lip length of 35 mm, and a distance between the aesthetic line and the lower lip of 5 mm were guidelines for planning the postsurgical outcome. Patient individual wishes concerning the profile were addressed within a permissible range to produce the best result. The planned horizontal and vertical movements of the soft tissue pogonion were set in relation to the necessary movement of the hard tissue pogonion using a soft-to-hard tissue ratio of 1.15:1 for horizontal movements and a ratio of 0.57:1 for vertical movements.

The genioplasty was performed as a bony resection of a central segment of the chin area ( Fig. 4 ). The anterior mandible was approached using an intraoral vestibular incision and subperiosteal dissection with exposure of the mental protuberance. Two horizontal parallel osteotomy lines starting from lateral downward towards the mental foramina and proceeding anteriorly between the roots of the teeth and the mental protuberance were created. After completing the osteotomy, the bony segment was removed and the muscular attachment was ligated and stripped off. The anterior bony chin part, including the mental protuberance and the broadest lingual musculo-periosteal pedicle, were setback in the cranial direction, advanced in the anterior direction, and replaced in the midline under bony contact to the mandibular corpus in accordance with the predictive parameters. The anterior chin segment was fixed with one cross-shaped osteosynthesis miniplate (Universal MP 2.0 system; Stryker Leibinger GmbH & Co. KG, Freiburg, Germany). Thereafter, the bony edges were trimmed to create a smooth transition from the genioplasty segment to the lateral contouring part. The mental muscles (Mm.) mentales were reconstructed and the approach was closed with resorbable sutures.

Fig. 4
Reduction genioplasty. (a) Exposing the mental protuberance and marking the amount of bony strip reduction. (b) Completion of the two horizontal parallel osteotomy lines. (c) Removal of the central bony segment. (d) Replacement of the anterior chin segment in the new position and osteosynthesis.

Statistics

The collected data were subjected to statistical analysis using the SPSS statistical software package, version 19.0 (SPSS, Chicago, IL, USA). The Kolmogorov–Smirnov test revealed a normal distribution of the datasets. Differences between groups were evaluated using the paired t -test. Results were considered significant if the P -value was less than 0.05 and highly significant if the P -value was less than 0.01. Pearson’s correlation analysis was used to assess the degree and significance of correlations between QoL impact scores and soft and hard tissue changes before and after surgery. Reliability of measurements was determined by randomly selecting 15 cephalograms and 15 lateral photographs to repeat the tracings by a second senior examiner. The method error was calculated using the formula: <SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='∑(X1−X2)2/2n’>(X1X2)2/2n∑(X1−X2)2/2n
∑ ( X 1 − X 2 ) 2 / 2 n
, where X 1 was the first measurement, X 2 the second measurement, and n the number of repeated records. All respective values of the method error calculation for the linear measurements ranged between 0.25 and 0.58 mm for cephalometry and between 0.29 and 0.54 mm for 2D photogrammetry, and for angular measurements, between 1.9° and 4.9° and between 1.8° and 4.5°, respectively. There were no significant differences between the examiners’ measurements.

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Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Reduction genioplasty enhances quality of life in female patients with prognathism and maxillary hypoplasia undergoing bimaxillary osteotomy
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