Anatomic and spiral computed tomographic study of the genial tubercles for genioglossus advancement

3D Genial Tubercle Anatomic Considerations in Genioglossus Advancement Surgery

OBJECTIVE

To qualitatively describe variation in morphology of the genial tubercle and quantify the spatial relationship between the tubercle and genioglossus muscle.

STUDY DESIGN

Case series.

SETTING

Cadaver dissection.

METHODS

Segmental sections of the mandible, with muscular attachments intact, were harvested from 18 fresh cadaver heads. Three-dimensional laser scans, with a resolution of 0.025 mm, were taken of each specimen with muscle attached and repeated after muscle removal. The genioglossus muscular attachment was measured relation to bony landmarks.

RESULTS

The morphology of the genial tubercle varied, with anywhere from 1 large spine to 4 individual spines. However, all specimens had a distinguishable superior portion of the tubercle, where the genioglossus attached, and an inferior portion, where the geniohyoid attached. The height of the superior tubercle (ST) was 6.1 mm (95% confidence inerval [CI]: 5.7-6.5). The height of the genioglossus muscle above the peak amplitude of the ST was 4.3 mm (3.8-4.9), but only 2.5 mm (2.0-3.0) below. On average, 64.4% (58.6-70.2) of the height of the genioglossus muscle attachment was above the peak. Overall, 19.5% (14.1-25.0) of the muscle surface area extended beyond the boundaries of the tubercle.

CONCLUSION

The genioglossus muscle attachment originates from the superior genial tubercle, which has a variable topography and amplitude. However, the muscle is not centered on the spines-more of the muscular fibers attach above the spine as compared to below. This new data may explain the genioglossus advancement "miss rate"-failure to advance muscle on initial osteotomy-of 39-78% reported in the literature.

Comparison of Genial Tubercule Anatomy Based on Age and Gender

Objective

In our study, it was aimed to determine whether there were differences in genial tubercle dimensions depending on age and gender.

Methods

In this study, 220 cone beam computed tomography (CBCT) images of patients (110 female and 110 male) between the ages of 20-80 years were obtained from the archive of İzmir Katip Çelebi University Faculty of Dentistry. All patients were divided into decade groups according to their age, and each decade group was divided into two subgroups according to gender. The genial tubercle was defined radiologically using axial, coronal and sagittal sections as well as 3D reconstruction image with NNT software program. Sagittal, vertical and horizontal dimensions of the genial tubercle were measured and statistically analyzed.

Results

There was a weak negative correlation between age groups and vertical values (r=-0.142; p=0.036) whereas the correlation coefficients between age groups and sagittal and horizontal values were not statistically significant (r=-0.043; p=0.530 and r=-0.039; p=0.563). There was a strong positive correlation between vertical and sagittal values in men (r=0.705, p<0.001) and women (r=0.714, p<0.001) in the whole group. There was a weak positive correlation between horizontal and sagittal, horizontal and vertical values in men (r=0.362, p<0.001; r=0.231, p<0.001) and women (r=0.304, p<0.001; r=0.257, p=0.007) in the whole group.

Conclusion

The vertical and horizontal dimensions of genial tubercle of men were higher than that of women. As the age of the patients increased, a decrease in the vertical values of the genial tubercle was observed.

A Modified Cosmetic Genioplasty Can Affect Airway Space Positively in Skeletal Class II Patients: Studying Alterations of Hyoid Bone Position and Posterior Airway Space

BACKGROUND

Improving the posterior airway space is one of the most important functions of genioplasty. Studies have shown that the posterior airway space (PAS) can play an important role in the evaluation of obstructive sleep apnea syndrome (OSAS). The purpose of this study is to evaluate the airway safety of our modified technology by observing the impact on PAS in skeletal Class II patients without OSAS.

METHODS

We have modified a cosmetic genioplasty, which can guarantee the continuity of the lower edge of the bilateral mandible by rotating the chin segment clockwise. Fourteen patients submitted to our modified cosmetic genioplasty alone were included in the study. The facial convexity angle and the ratio of the face were measured by analyzing photographs. The position of the hyoid bone and the width of the PAS were measured by analyzing lateral cephalograms. The volume and the cross-sectional area (CSA) of the PAS were measured using 3D reconstruction. The Wilcoxon signed-rank test and paired samples t test were used to assess the significance of differences of the data (p < 0.05).

RESULTS

Soft tissue measurements were statistically different (p = 0.001) and achieved satisfactory results. The position of the hyoid bone moved up (L_X: p = 0.004; L_ML: p = 0.056) and forward (L_Y: p = 0.001; L_CV3: p = 0.016). The increase in the CSA had statistical significance (p < 0.005). There were significant statistical differences in the total airway volume and hypopharynx (p = 0.001), except in the oropharynx (p = 0.096).

CONCLUSIONS

Our modified genioplasty not only achieved better cosmetic results by ensuring the continuity of the lower edge of the bilateral mandible but also exerted a significant positive impact on the posterior airway space for patients with skeletal class II, thus helping reduce the prevalence of OSAS. We hence suggest performing this modified cosmetic genioplasty on the skeletal class II patients with/without OSAS if necessary.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Comparison of anterior mandible anatomical characteristics between obstructive sleep apnea patients and healthy individuals: a combined cone beam computed tomography and polysomnographic study

PURPOSE

This study aims to evaluate the morphology of the genial tubercle (GT) and lingual foramen (LF) between obstructive sleep apnea (OSA) and non-OSA patients for considerations of mandibular advancement surgery.

METHODS

Cone beam CT records of 198 patients were retrospectively collected and analyzed. Five variables were measured for genial tubercle; anterior mandible thickness (AMT), the distance from the lower incisors to the superior border of the genial tubercle, the distance from the inferior border of the genial tubercle to inferior border of the mandible, the height of GT, and genial tubercle width. Lingual foramen were classified according to the genial tubercle. The frequencies, distances of lingual foramen to alveolar crest, lower border of mandible (LVDL) and diameter of LF were also measured.

RESULTS

Significant differences was found for genial tubercle width, anterior mandible thickness, and the distance of lower mandibular border to the midline lingual foramina between OSA and non-OSA patients (p < 0.05). AMT gets thicker and GT gets narrower in OSA patients (p < 0.05). A linear regression analysis on the apnea hypopnea index with measured anatomical variables showed the LVDL (R = - 0.355*), body mass index (R = 0.254), and age (R = 0.33) showed a statistically significant association (p < 0.05). None of the other variables reached formal significance.

CONCLUSION

LVDL is linearly associated with sleep apnea severity. The variable dimensions and anatomy of genial tubercle as well as lingual foramen for OSA patients suggest the need of 3D preoperative radiological evaluation before genioglossus advancement surgery. Cone beam CT can be a powerful low radiation dose tool both for evaluating the anatomy of the upper airway and mandibular structures at the same time for OSA patients.

Genial tubercle position and genioglossus advancement in obstructive sleep apnea (OSA) treatment: a systematic review

Background

To systematically review the literature for methods to localize the genial tubercle as a means for performing an advancement of the genioglossus muscle.

Methods

PubMed, Google Scholar, CRISP, EMBASE, CINAHL, and Scopus were searched from inception through June 16, 2015.

Results

One hundred fifty-two articles were screened, and the full text versions of 12 articles were reviewed in their entirety and 7 publications reporting their methodology for localizing the genial tubercle. Based upon these measurements and the results published from radiographic imaging and cadaveric dissections of all the papers included in this study, we identified the genial tubercle as being positioned within the mandible at a point 10 mm from the incisor apex and 10 mm from the lower mandibular border.

Conclusion

Based upon the results of this review, the genial tubercles were positioned within the mandible at a point 10 mm from the incisor apex and 10 mm from the lower mandible border. It may serve as an additional reference for localizing the genial tubercle and the attachment of the genioglossus muscle to the mandible, although the preoperative radiological evaluation and the palpation of the GT are recommended to accurately isolate.

Genial tubercles: Morphological study of the controversial anatomical landmark using cone beam computed tomography

BACKGROUND

Identification of the morphology of the genial tubercles (GTs) is valuable for different dental applications. The morphological pattern of the GTs is still controversial, and therefore, the study of its morphology using cone beam computed tomography (CBCT) plays a valuable role in resolving the controversy.

AIM

To assess the morphological pattern, dimensions and position of the GTs using CBCT among a selected Saudi population.

METHODS

CBCT records of 155 Saudi subjects (49 female and 106 male) were used to assess the pattern and size of the GTs and to determine the distance from the apices of the lower central incisors to the superior border of the GTs (I-SGT) and the distance from the inferior border of the GTs to the menton (IGT-M).

RESULTS

The results of this study showed that the most common morphological pattern was of two superior GTs and a rough impression below them (36.8%), followed by two superior GTs and a median ridge representing fused inferior GTs below them (22.6%) and a single median eminence or projection (20%). The classically described pattern, of two superior and two inferior GTs placed one above the other, was found in only 14.2% of cases, while 6.4% of the studied cases had no GTs. The mean width and height were 6.23 ± 1.93 mm and 6.67 ± 3.04 mm, respectively, while the mean I-SGT and IGT-M measurements were 8.26 ± 2.7 mm and 8.13 ± 3.07 mm, respectively.

CONCLUSION

The GTs are a controversial anatomical landmark with wide variation in their morphological pattern. The most common pattern among the studied Saudi sample was of two superior GTs and a rough impression below them, and there were no significant differences between males and females.

Effects of Hat-Shaped Mortised Genioplasty with Genioglossus Muscle Advancement on Retrogenia and Snoring: Assessment of Esthetic, Functional, and Psychosocial Results

BACKGROUND

An increasing number of patients undergo genioplasty for esthetic purposes to correct micrognathism or retrognathism. However, these conditions are considered an important risk factor for snoring. The purpose of this study was to evaluate both esthetic improvement and functional changes of snoring symptoms in patients who underwent hat-shaped mortised advancing genioplasty with genioglossus muscle advancement.

MATERIALS AND METHODS

This retrospective study enrolled 25 patients. We evaluated scores for subjective snoring classification (Stanford scale) and questionnaire findings for esthetic results.

RESULTS

Most people (96%) were satisfied with the esthetic improvement after surgery. The grade of subjective snoring classification (Stanford scale) improved from 8.68 (range 0-10) to 4.08 (range 0-10) after surgery. Twenty-four patients had an improved snoring grade. All patients reported a positive impact on their daily activity and self-confidence, and they were willing to recommend the same operation to someone with the same clinical problems.

CONCLUSION

We conclude that hat-shaped mortised advancing genioplasty with genioglossus muscle advancement can relieve the symptoms of snoring for patients with hypoplastic chin or retrogenia. Patients were satisfied with the functional and esthetic results.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Genioglossus Advancement and Hyoid Surgery

The structure and dimensions of the mandible, tongue, and hyoid complex are important variables in the pathophysiology of obstructive sleep apnea at the hypopharyngeal level. Genioglossus advancement is based on mandibular osteotomy, which brings the genioglossus muscle (GGM) forward and prevents posterior collapse during sleep. The genioglossus advancement technique has recently undergone several modifications; each has attempted to minimize surgical morbidity while improving the incorporation and advancement of the GGM. The hyoid bone has been of interest in sleep apnea and apnea-related surgical procedures because of its integral relationship with the tongue base and hypopharynx. Hyothyroidopexy is illustrated.

Anatomical analysis to establish the optimal positioning of an osteotomy for genioglossal advancement: a trial in cadavers

Genioglossal advancement, which is one of the treatments for obstructive sleep apnoea, can be effective only if it contains enough genial tubercle for an osteotomy. The aim of this study was to establish the position of the genial tubercle and of the optimal osteotomy during genioglossal advancement. Twenty-four adult cadavers with intact bony mandibular structures were included. Five variables were measured: the width and height of the genial tubercle (GTW); the distance from its inferior border to the inferior border of the mandible (IGT-IBM); the distance from the superior border of the genial tubercle to the inferior border of the mandible (SGT-IBM); and the width of the intermental foramen (IMFW). The following mean (SD) (range) measurements were obtained: GTW 7.38 (1.43) (4.5-10.0); GTH 7.94 (1.45) (5.0-10.0); IGT-IBM 7.96 (2.29) (4.0-12.0); SGT-IBM 15.90 (2.29) (12.0-20.0); and IMFW 56.65 (6.44) (43.0-67.0) mm. Of the 24 cadavers, 22 showed evidence of optimal positioning when the osteotomy was placed 2mm higher than the SGT-IBM measured on the inner table. This suggests that an optimal osteotomy, which includes the genial tubercle, may be possible in most patients when the osteotomy is positioned 2mm higher at the SGT-IBM.

Where to position osteotomies in genioglossal advancement surgery based on locations of the mental foramen, canine, lateral incisor, central incisor, and genial tubercle

PURPOSE

The study aimed to provide precise measurements of anterior mandibular structural anatomy and to explore potential osteotomies for genioglossal advancement.

METHODS

Cone beam computed tomography was used to analyze 33 randomly selected patients undergoing surgery for obstructive sleep apnea (OSA) between 2014 and 2016 at an academic surgical hospital. The locations of relevant mandibular structures were measured and statistical modeling was performed.

RESULTS

Mean horizontal distances from midline to the mental foramina and the roots of the canine, lateral incisor, and central incisor were 22.11 ± 1.92, 13.56 ± 3.01, 6.19 ± 1.58, and 2.04 ± 0.87 mm, respectively. Mean vertical distances from the inferior border of the mandible were 15.15 ± 1.77, 17.11 ± 3.28, 20.48 ± 3.10, and 21.81 ± 3.49 mm, respectively. The superior border of the genial tubercle was 15.63 ± 2.75 mm, and the inferior border was 6.87 ± 3.29, from the inferior border of the mandible. The angle of decline of the best-fit line through the important structures was about 18° from the occlusion plane at the midline.

CONCLUSIONS

A straight line estimating the mental foramen, canine, lateral incisor, and central incisor tooth roots crosses at a mean of 22.3-22.6 mm above the inferior border of the mandible at the midline and has an angle of decline of about 18°. Potential osteotomies made parallel to and below this line result in tradeoffs between maximizing capture of the genioglossus muscle attachment and risk of dental/neurovascular injury.

Evaluation of genial tubercle anatomy using cone beam computed tomography

The purpose of this study was to characterize the anatomy of the genial tubercle using cone beam computed tomography (CBCT). The morphology and detailed anatomy of the genial tubercle were assessed retrospectively in 201 patients (101 females, 100 males) using CBCT images. The parameters examined were the height (GH) and width (GW) of the genial tubercle, the distance from the lower incisors to the superior border of the tubercle (I-SGT), the distance from the inferior margin of the tubercle to the inferior margin of the mandible (IGM-IBM), and the anterior mandible thickness (AMT). Statistical analysis was performed to assess relationships among these parameters, gender, and orthodontic malocclusion (P < 0.05). The values obtained were GH 7.3-8.7 mm, GW 7.9-9.2 mm, I-SGT 7.1-9.1 mm, IGM-IBM 8.3-10.1 mm, and AMT 14.0-16.2 mm. GH, GW, and I-SGT showed no significant differences between genders (P > 0.05). However, IGM-IBM was larger for class III than for class I and class II male patients, and larger than for class I female patients. AMT in class III patients was greater than in class I and II patients (P < 0.05). The use of CBCT, which employs less radiation, is important for dental professionals, especially those performing surgery for obstructive sleep apnea (OSA), in order to avoid possible surgical complications.

Analysis of Mandibular Structure Using 3D Facial Computed Tomography

Objective

This study measured and analyzed the position and dimension of genial tubercle (GT) and mental foramen (MF)

Study Design

Retrospective chart review study.

Setting

Tertiary care teaching hospital.

Subjects and Methods

Two hundred ten subjects were included who received 3-dimensional (3D) facial computed tomography (CT), and the GT and MF were evaluated. Subjects were divided into 4 groups by gender and skeletal type. Seven variables were measured: (1) height of GT (GTH), (2) width of GT (GTW), (3) distance from apices of lower incisors to superior border of GT (LI-SGT), (4) distance from inferior border of GT to inferior border of mandible (IGT-IBM), (5) thickness of anterior mandible (MT), (6) distance from symphysis of mandible to MF (S-MF), and (7) distance from superior border of GT to inferior border of mandible (SGT-IBM).

Results

All the parameters showed marked differences in individuals. Class I males showed longer GTH, MT, and SGT-IBM than class I females ( P < .05). IGT-IBM and S-MF were longer in class II males than in class I females ( P < .05). LI-SGT and IGT-IBM also showed personal variation.

Conclusion

Anatomical features of mandibular structures showed individual variations. GTH, IGT-IBM, MT, S-MF, and SGT-IBM also showed differences between the groups.

Mandibular Atrophy and Genial Spines Enlargement on Cone Beam Computed Tomography

Purpose. The aim of this paper is to report a case in which the cone beam computed tomography (CBCT) was important for the confirmation of the presence of mandibular atrophy and genial spines enlargement. Case Description. A 76-year-old female patient was referred for the assessment due to the complaint of chronic trauma in the anterior region of the floor of the mouth, which had been present for 2 months. CBCT images showed severe resorption of alveolar ridge and genial spines enlargement (5.5 mm × 12 mm). Conclusion. Accurate imaging assessment with the aid of 3D reconstructions allows the elimination of image superimposition and, therefore, plays an important role in the depiction of anatomical and pathological conditions, such as genial spines enlargement.

Genial tubercle position and dimensions by cone-beam computerized tomography in a Taiwanese sample

OBJECTIVE

. The aim of this study was to evaluate the position and dimensions of the genial tubercle in a Taiwanese sample.

STUDY DESIGN

Cone-beam computerized tomography (CT) records of 90 adult patients with class I or class II skeletal type were used to evaluate the position and dimensions of the genial tubercle and dimensions of the anterior mandible. Subjects were grouped by sex and skeletal type.

RESULTS

In all groups, the genial tubercle height was close to the genial tubercle width. The distance from the inferior border of the genial tubercle to the inferior border of the mandible was greater in class II male patients than in class I female patients (P < .05). The anterior mandible in class I male patients was thicker than in class II female patients (P < .05).

CONCLUSIONS

The variable position and dimensions of this structure among patients suggest the need for cone-beam CT before attempting genioglossus advancement to treat obstructive sleep apnea.

Rare enlargement of the genial tubercles. Enlargement of genial tubercles

Genial tubercles usually are small bony protuberances on the lingual aspect of the mandible symphysis. Conversely, this case shows 3D tomographic reconstruction images of genial tubercles as an oversized projection causing pain and discomfort to the patient.

Reorganization of sleep architecture after surgery for OSAHS

CONCLUSION

Genioglossus advancement and hyoid suspension (GAHM) plus uvulopalatopharyngoplasty (UPPP) can decrease the apnea hypopnea index (AHI) and arousal index, especially respiratory-related arousals. Correspondingly, sleep architecture is reorganized, which is expressed postoperatively as an increase in slow wave sleep and a decrease in lighter sleep.

OBJECTIVE

To explore the reorganization of sleep patterns after GAHM plus UPPP for severe obstructive sleep apnea hypopnea syndrome (OSAHS).

PATIENTS AND METHODS

GAHM plus UPPP was performed on 31 patients with severe OSAHS (AHI > 40). The postoperative follow-up was 6 months.

RESULTS

The AHI was reduced from 65.93 +/- 23.83 preoperatively to 28.58 +/- 29.11 postoperatively. The arousal index was reduced from 56.00 +/- 18.78 to 41.97 +/- 20.73, and the respiratory arousal index was reduced from 35.44 +/- 21.57 to 22.63 +/- 21.99. No significant change was seen in the spontaneous arousal index (preoperative, 20.56 +/- 12.97; postoperative, 19.34 +/- 10.29). The percentage of REM sleep during the total sleep time (TST) increased from 10.53 +/- 9.13% to 13.92 +/- 6.76%, and the S3 + S4 percentage of TST increased from 3.07 +/- 3.01% to 7.09 +/- 6.83%. Correspondingly, the S1 + S2 percentage of TST decreased from 86.53 +/- 9.28% to 78.89 8.89%.