Genial Segment Research Articles

Evaluation of trabecular changes following advancement genioplasty combined with or without bilateral sagittal split osteotomy by fractal analysis: a retrospective cohort study

BackgroundIt is aimed to investigate whether there was a difference in radiographic changes in the operational areas between genioplasty alone and genioplasty combined with mandibular advancement and to evaluate the fractal dimension (FD) to assess trabecular changes after genioplasty surgery.MethodsPreoperative-(T0) and postoperative-(T1) panoramic radiographs of 26 patients without any complications who underwent genioplasty combined with bilateral sagittal osteotomy and mandibular advancement or genioplasty alone were selected. In the panoramic radiographs of both groups, the genial segment, mandibular angulus, and surgical osteotomy line were examined using FD. The box-counting method was used for FD evaluation.ResultsIt was determined that FD values before and after treatment were similar in both groups for all regions where measurements were made. After surgery, the FD values of the middle region of the genial segment were found to be significantly lower than the other regions. At T1, the FD values at the osteotomy area were found to be significantly higher than those in the middle region of the genial segment.ConclusionTrabecular structure does not differ in patients undergoing genioplasty alone or in combination with mandibular advancement osteotomy. The middle region of the genial segment heals later than other regions.

Mandibular symphysis fracture associated with the displacement of a fractured genial segment: An unusual case report with review

Fractures and displacement of fragments involving the genial tubercles due to trauma are rarely seen in patients with a full complement of teeth although spontaneous fractures of the genial tubercles in edentulous atrophic mandible are not uncommon. These are usually displaced and may be missed during routine clinical and radiographic examinations owing to superimposition of the features of a fractured mandible. Very few cases have been reported till date. Their implications lie in functional alterations that occur as a consequence of loss of attachment of the geniohyoid and genioglossus muscles. There is no universal opinion on the treatment of fractures involving the genial tubercles. Possible treatments include no surgical intervention, excision of the avulsed bone fragments, and muscular repositioning. We present a case of mandibular fracture associated with the fracture and displacement of a fragment involving the genial tubercles in a dentate patient where in the finding was incidental and a review of literature.

Evaluation of a three-stage method for improving mandibular retrognathia with labially inclined incisors using genioplasty, segmental osteotomy, and two-jaw surgery.

We have sometimes encountered difficulty in improving labially inclined teeth, particularly in patients with mandibular retrognathia, because the symphysis menti is often thin and insufficient space is available to permit sagittal rotation of the teeth without root exposure from the alveolar bone. We have previously described a three-stage method to overcome this problem, involving genioplasty for improving the retruded chin, and to construct the infrastructure for subsequent subapical segmental alveolar osteotomy, subapical segmental alveolar osteotomy itself, and, finally, two-jaw surgery. Bone augmentation with thin cortical bone at the gap created on the upper surface of the advanced genial segment was also addressed in the previous report. In the present study, to confirm the benefits of the three-stage method using objective data, cephalometric evaluation was performed in each step. In all cases, pogonion (Pog) was moved forward substantially. Net linear forward movement of Pog and net changes in SN-Pog were from 12 mm to 20 mm and from 4.8° to 7.0°, respectively. Angle of mandibular incisors and interincisal angle also improved to desirable levels. Although this method requires three separate surgeries, the approach safely improves the clinical situation and accentuates treatment efficacy.

Immediate Osseous Genioplasty With Kirschner Wire Fixation for Revision of Infected Alloplastic Chin Implant

Genioplasty is a useful tool for correction of congenital abnormalities, as well as for aesthetic improvements of the lower face. Both alloplastic implantation and osseous genioplasty techniques have long been used successfully to achieve satisfactory outcomes. However, alloplastic implantation can be associated with several known complications, including infection, bone resorption, and secondary soft tissue deformities. Typically, these issues arise in the early postoperative period, but there have been reported instances of late infectious complications and the associated sequelae. These cases are generally treated with removal of the implant and secondary revision at a later date. We present here the unique case of a 65-year-old woman who presented with an infected silicone chin implant 25 years after her initial surgery. In this case, we chose to perform an immediate osseous genioplasty at the time of implant removal to avoid the problems that can arise from unpredictable soft tissue healing, as well as an untoward aesthetic result from the significant bone resorption that had occurred in this patient. To minimize the presence of exposed hardware in this contaminated field, we used intraosseous Kirschner wire fixation for osteosynthesis of the advanced genial segment. Our patient experienced no complications from this procedure, the infection cleared, and a successful aesthetic outcome was achieved with this technique.

Preliminary studies on the use of BMPs in Orthognatic surgery

The amount of postoperative bone esorption after genioplasty was studied n 16 patients. The subjects of this study ere 5 patients who underwent genioplasty lone, and 11 who underwent genioplasty ombined with other techniques for corecting skeletal Class II and Class III eformity. Large advancement genioplasties were erformed on 16 patients by horizontal steotomy of the inferior border of the andible, with preservation of a muscuoperiosteal pedicle to the advanced genial egment. Preoperative, immediate postoprative, and long-term follow-up lateral ephalometric radiographs were retrospecively analyzed to evaluate the osseous hanges of the chin. We examined the corelation between bone resorption and the egree of advancement, the height of the enial segment, and the distance from the xisting bone to the genial segment. The esults showed a correlation between bone esorption and the distance from existing one to the genial segment. We can thereore expect the supply of blood between xisting bone and the genial segment to ave an influence on bone resorption. Conflict of interest: None declared.

Advancement Genioplasty––Cephalometric Analysis of Osseous and Soft Tissue Changes

Genioplasty is often performed to esthetically improve patient's profiles in the lower facial third. Many factors account for the variability in soft tissue response like dissection technique, magnitude and direction of movement and stability of the genial segment. Optimum treatment planning thus requires an understanding of the soft tissue response to various genial procedures. To determine the stability, ratio of hard and soft tissues and changes in the lower facial profile after advancement genioplasty. Ten patients were evaluated cephalometrically for the soft tissue changes in relation to hard tissues after advancement genioplasty. Pre operative, immediate post operative and 6months post operative lateral cephalogram were taken. Pre operative tracings were superimposed with post operative cephalograms to produce a composite tracing. Changes in the osseous tissues are assessed and related to the net changes in the soft tissues. The ratio of horizontal changes of osseous to soft tissues was found to be 1:0.89. The mean resorption was 0.85mm (10.7%). The vertical changes are minimal and non significant. There are significant changes in the soft tissue profile such as decrease in the soft tissue thickness, facial convexity angle, lower facial submental angle and increase in mentolabial sulcus depth. The standard advancement genioplasty procedure by inferior osteotomy of the chin with broadest musculo-periosteal pedicle with rigid internal fixation was followed. The soft tissue response is almost equal to the bony movement. The stability of the hard tissues is good with minimum amount of resorption so as to achieve more predictable results.

水平骨切りによるオトガイ形成術後の骨吸収に関する検討

The amount of postoperative bone resorption after genioplasty was studied in 13 patients. The subjects of this study were 4 patients who underwent genioplasty alone, and 5 who underwent genioplasty combined with other techniques for correcting skeletal Class II and Class III deformities.Large advancement genioplasties were performed on 13 patients by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculoperiosteal pedicle to the advanced genial segment. Preoperative, immediate postoperative, and long-term follow-up lateral cephalometric radiographs were retrospectively analyzed to evaluate the osseous changes of the chin. We examined the correlation between bone resorption and the degree of advancement, the degree of mandible movement, the height of the genial segment, and the distance from the existing bone to the genial segment. The results showed a correlation between bone resorption and the distance from existing bone to the genial segment. This suggests that the supply of blood between existing bone and the genial segment has an influence on bone resorption.

Horizontal Flip Pedicled Genioplasty for Correction of Asymmetric Chin in Adult Unilateral Temperomandibular Joint Ankylosis

It has been the desire and a great challenge to clinicians treating maxillofacial deformities to bring about symmetry in asymmetric faces. As one understands, it is very difficult to reproduce nature, that is, the normal side out of abnormal side, and it is easier to manage bilateral symmetrical deformities. Temporomandibular joint (TMJ) ankylosis, when it occurs in early childhood, will have devastating effects on the future growth and development of the jaws and teeth with obvious facial deformity including the chin, which worsens with advancing age and the time elapsed between the onset of ankylosis and the treatment instituted. We have been treating these chin deformities in adult unilateral TMJ ankylosis cases for over more than a decade with horizontal flip pedicled genioplasty, which has a mathematical basis of turning a scalene triangle to an isosceles triangle and thereby achieving symmetry. Fixation of the genial segment in an overriding position not only adds to the length of mandible but also overcomes the obstructive sleep apnea many times associated with TMJ ankylosis. We have successfully treated 15 patients using horizontal flip pedicled genioplasty during last 14 years. This instantaneous corrective and unique technique requiring minimal patient compliance is put forward with refinements developed during a period of years.

Chin Augmentation With Thin Cortical Bone Concomitant With Advancement Genioplasty

The chin plays a prominent role in establishing, not only esthetics, but also function. An incompetent lip seal and tension of the mentalis muscle in swallowing can be important symptoms. Genioplasty is one of the options for addressing the chin deformity and dysfunction caused by morphologic dcficiencies. 1 Postoperative complications can include resorption of grafted bone and a deep labiomental fold. Lateral wings of the genial segment are apt to be resorbed, occasionally leading to the so-called witch's chin appearance, 2 if combined with a deep labiomental fold. To overcome this problem, various strategies have been reported. 3 We describe a novel method to augment the chin structure with a desirable labiomental fold using thin cortical bone alone. Surgeons generally depend on radiography or computed tomography to evaluate genioplasty. However, we had the opportunity to see firsthand the actual state of bony union in these cases when subsequent anterior subapical alveolar osteotomy was performed several months later. We report 2 cases in which substantial bone augmentation was achieved.

Chin Surgery V: Treatment of the Long, Nonprojecting Chin

Correction of the long, nonprojecting chin requires both vertical reduction and sagittal augmentation. Wedge excision-based therapy reduces chin height and allows for advancement of the distal segment, but it is associated with at least a 10 percent incidence of mental nerve injury. The authors propose two innovative ways to correct the long, nonprojecting chin. There are two approaches, intraoral and extraoral. With the intraoral approach, following a gingivobuccal incision, a single horizontally oblique osteotomy is made at least 6 mm beneath the mental nerve foramina. The vertically long genial segment is freed and the posterior edge is contoured with a side-cutting burr. The contoured jumping genial segment is secured to the mandible with countersunk screws and contoured in situ to preserve the lower 8 to 10 mm. With the extraoral approach, following a submental incision, the anterior and posterior surfaces of the symphysis are cleared (a double-armed suture is placed through the posterior musculature). A reciprocating saw is used to remove the lower border of the symphysis to reduce the vertical excess. The tagged musculature is resuspended, and a tapered, textured implant is secured to the new symphysis. Aesthetic outcomes using these two techniques were good and there were no complications. Representative patients, operated on by the senior author, illustrate these techniques. Both the intraoral one-cut in situ contoured jumping genioplasty and the extraoral vertical reduction/sagittal augmentation genioplasty reduce excess chin height, control sagittal advancement, provide pogonion projection, and avoid the risks of a standard wedge. Both techniques provide custom projection at the lower pole of the new symphysis.

軟組織を最大限に付着するオトガイ骨切り前方移動形成術の術後安定性について

We evaluated the postoperative stability of broad soft tissue pedicle genioplasty. This surgical procedure involves horizontal osteotomy of the inferior border of the mandible while maintaining a musculoperiosteal pedicle.Lateral chephalometric radiographs of 20 patients who underwent broad soft tissue pedicle genioplasty were analyzed to evaluate osseous and soft tissue changes of the chin. We found that the pedicled genial segment had no relapse, and the soft tissue had only slight relapse. In addition, bone remodeling was seen at the symphysis of the genial segment. Broad soft tissue pedicle genioplasty had good postoperative stability.

骨間貫通ネジ骨接合術のオトガイ形成術への応用

Genioplasty is a routine procedure for the improvement of profile in the correction of dentofacial deformities. Horizontal osteotomy of the inferior border of the mandible is usually performed. Osteotomized genial segment has conventionally been fixed with wire osteosyntheses. However, since this method had many disadvantages, use of rigid internal fixation with mini bone plates and screws or screws alone in genioplasty has spread. Rigid internal fixation provides a rapid and rigid means of stabilizing the inferior mandibular fragment after horizontal osteotomy, and is able to achieve the optimum bony union and the small resorption of bone. Moreover, screw fixation seems to have advantages over mini bone plates and screws, and also lag screw fixation seems to have advantages over position screw fixation.In 1989, we began using lag screw fixation after horizontal osteotomy in genioplasty by the use of only one titanium mini non self-tapping screw in the median part of the chin, and this screw is inserted through inferior approach and fixed to the lingual cortex of the mandible.So far, we have used it in 50 cases.This method has the following advantages:1. Excellent rigid osteosynthesis.2. Easy and rapid procedure.3. Easy removal.

Assessment of chin surgery by a coordinate free method

A quantitative description of the changes and stability after genioplasty in a cross-sectional sample of 19 patients who had advancement genioplasty is presented. Euclidean distance matrix analysis (EDMA) of five cephalometric landmarks was used to assess these changes. During the first 6 months after surgery, bone deposition occurred at B point and pogonion, with bone resorption at the superior and posteroinferior aspects of the advanced segment. The genial segment rotated slightly anticlockwise. The authors believe this to be due to the action of the mentalis muscles. The stability of the advanced segment was excellent when assessed 1 year after surgery. The Euclidean distance matrix method can be used to assess shape changes and does not require cephalographic superimposition. It can also distinguish repositioning from remodelling and the changes of genioplasty from those of concomitant orthognathic surgery.

Evaluation of changes following advancement genioplasty using finite element analysis

This study examined skeletal stability and the remodelling process following advanced pedicled genioplasty. Twenty patients who had advancement genioplasty concomitant with other adjunctive orthognathic surgery were evaluated. A finite element analysis method was used to assess these changes. The stability of the advanced segment was excellent after 6 months. At 6 months bone remodelling was observed in the form of bone apposition at B point and Pogonion with bone resorption at the superior aspect of the advanced segment. The genial segment rotated about 12 degrees antero-superiorly which was thought to be due to the action of the mentalis muscle. Finite element analysis is a sensitive tool for assessing changes after genioplasty and was able to separate them from the effects of other adjunctive orthognathic surgery.

Long-term osseous and soft tissue changes after large chin advancements

When a large chin advancement is performed and a broad musculo-periosteal pedicle is preserved, excessive stretching of the suprahyoid musculature may occur, leading to instability or resorption of the advanced genial segment. The present study was designed to evaluate long-term osseous and soft tissue changes after large advancement genioplasties (greater than 10 mm), achieved by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculo-periosteal pedicle to the advanced genial segment. Bone remodeling and the inherent soft tissue changes were radiographically assessed in a long-term follow-up period (mean = 26.8 months), with attention to observe progressive osseous changes. Despite the observed 17% bone resorption, the enveloping soft tissues of the chin followed the bony movement in a ratio of 1:0.83. Osseous resorption was not progressive, and the soft tissue changes remained unaltered. A broad musculo-periosteal pedicle consistent with the surgical objective should remain attached to the advanced genial segment to minimize osseous resorption and achieve more predictable soft tissue changes. We emphasize the need for a longer follow-up period (25-30 years) to determine the effect of the stabilization devices and osseous remodeling, specially in younger patients.

A retrospective study of advancement genioplasty using a special bone plate

This study evaluates skeletal stability and the remodeling process of the advanced genial segment when a single bone plate is used to stabilize the segment following osteotomy of the inferior border of the mandible. Thirty-nine patients with a minimum of 6 months follow-up who had advancement genioplasty stabilized with a Paulus chin plate were analyzed using cephalometrics and clinical examination. The results showed that stability of the result was excellent; pogonion maintained its immediate postsurgical horizontal position at longest follow-up. The remodeling pattern observed was similar to that reported in other studies using alternate forms of fixation in spite of the fact that the bone plate covered the areas where most remodeling occurs.

Long-term Stability of the Chin after Broad Soft-tissue Pedicle Genioplasty

Broad soft-tissue pedicle genioplasties were performed in 6 patients by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculoperiosteal pedicle to the genial segment. Preoperative, immediate postoperative, and long-term follow-up lateral cephalometric radiographs were retrospectively analyzed to evaluate the osseous and soft-tissue changes of the chin. After a mean follow-up period of 29 months, all cases preserved the initial advancement. No case showed bone resorption from pogonion to the menton region.The chins advanced by broad soft-tissue pedicle genioplasty had good stability.

Soft tissue changes after advancement genioplasty performed as pedicled or free transplants

The influence of soft tissue attachment in augmentation genioplasty on postoperative soft tissue changes was studied in 25 patients. The soft tissue was completely detached from the advanced genial segment in 14 patients and lingual soft tissue was maintained in 11 patients. The patients were followed for a minimum of 1 year after operation and the soft tissue and bone changes were analysed by measuring linear distances and areas on lateral cephalograms. The result indicated that the soft tissue changes after surgery were significantly different between the two types of graft. In the free grafts there was found to be an increased risk of creating a larger interlabial gap and exposure of the labial surface of mandibular incisors. The higher correlations between hard and soft tissue changes in the pedicled grafts indicated that the predictability is better with this operative technique.

Bone resorption after advancement genioplasty: Pedicled and non-pedicled grafts

The influence of soft tissue attachment in augmentation genioplasty on the amount of postoperative bone remodelling was studied in 29 patients. The soft tissue was completely detached from the advanced genial segment in 15 patients and the lingual soft tissue was maintained in 14 patients. The advancement of the chin and postoperative bone remodelling was analysed by measuring linear distances and areas on lateral cephalograms. The genial segments with a soft tissue pedicle underwent significantly less resorption than the free grafts (p less than 0.01). The difference in postoperative infection between the two groups (p less than 0.05) indicates that the likelihood of postoperative infection is significantly reduced by maintaining the soft tissue pedicle. Considerably less variation in amount of bone resorption was also observed in the patients with a pedicled graft.

Bone resorption, stability, and soft-tissue changes following large chin advancements

Large advancement genioplasties were performed in 10 patients (mean advancement, 11.7 mm) by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculoperiosteal pedicle to the advanced genial segment. Preoperative, immediate postoperative, and long-term follow-up lateral cephalometric radiographs were retrospectively analyzed to evaluate the osseous and soft-tissue changes of the chin. After a mean follow-up period of 15 months, 76% of the initial advancement was preserved, representing 24% osseous resorption. The enveloping soft tissues of the chin followed the bony movement in a ratio of 1:0.88. Horizontal osteotomy of the inferior border of the mandible was a relatively stable procedure when used for large chin advancements. The broadest possible musculoperiosteal pedicle should remain attached to the advanced genial segment to minimize osseous resorption and to achieve more predictable soft-tissue changes.