Splintless orthognathic surgery in edentulous patients—a pilot study

The aim of this pilot study was to evaluate the accuracy and predictability of a splintless treatment protocol for edentulous patients undergoing orthognathic surgery in four consecutive cases. All operations were virtually planned, followed by computer-aided design of individual osteotomy guides and patient-specific fixation implants, which were three-dimensionally printed in titanium. In order to evaluate the discrepancy between the planned and the achieved postoperative result, the postoperative outcome was compared to the virtual treatment plan. Rotational and translational movement and discrepancies with the planned movements were quantified for the maxilla; the advancement was quantified for the mandible. For the maxilla, there was a mean translation discrepancy of 0.6 mm. With regard to rotation, there was a mean discrepancy of 1.9°, 0.1°, and 0.4° for pitch, yaw, and roll, respectively. The mean discrepancy in translation of the mandible was 0.4 mm. The results of this pilot study indicate that the splintless treatment protocol for orthognathic surgery in edentulous patients presented here is accurate and predictable.     

Changes in bite force and occlusal contact area after orthognathic surgery for correction of mandibular prognathism

OBJECTIVE: This study examined the long-term changes of bite force and occlusal contact area in patients with prognathous after orthognathic surgery with a newly developed pressure-sensitive sheet (Dental-Prescale; Fuji Photo Film Co). STUDY DESIGN: Fifty-seven patients with prognathous were examined. Bite force and occlusal contact area were measured just before operation and at 2 weeks, 1 month, 3 months, 6 months, 1 year, 2 years, and 3 years after operation. Forty control subjects with normal occlusion were also measured. RESULTS: The bite force and occlusal contact area of the patients were significantly greater than the preoperative level at 1 year, 2 years, and 3 years after operation. However, they were still significantly lower than the control subject level even at 3 years after operation. CONCLUSIONS: This study suggests that orthognathic surgery improves the bite force and occlusal contact area of patients with prognathous. However, at 3 years from the time of operation, patients had not reached control subject levels.     

Changes in stomatognathic function induced by orthognathic surgery in patients with mandibular prognathism.

PURPOSE: This study was designed to investigate the changes in stomatognathic function through orthognathic treatment in patients with mandibular prognathism. PATIENTS AND METHODS: Thirty-six patients with mandibular prognathism were tested and compared with 30 healthy controls with normal occlusion. For each subject, the occlusal contact area and occlusal force were measured during maximum voluntary clenching (MVC). Activities of the masseter and temporalis muscles were recorded during MVC and voluntary gum chewing. Jaw movement was analyzed during chewing on the left and right sides. For the analyses, 2 parameters, asymmetry index (AI) and error index (EI), were established to further investigate the nature of masticatory function. AI was used to evaluate the bilateral balance of masticatory muscle activity, and EI indicates the rate of abnormal jaw movement pattern. RESULTS: In patients with mandibular prognathism, the occlusal contact area and maximum bite force decreased before surgery, and increased after surgery. The masseter and temporal muscle activities also decreased before surgery, but showed no substantial increase even after surgery. The occlusal and muscle efficiency exhibited significantly smaller values in the patient group than in the controls, irrespective of treatment stages. The AI decreased after surgery. The EI decreased significantly after surgery, but was still significantly greater in the patient group than in the controls. CONCLUSIONS: It is suggested that masticatory muscles in the patients with mandibular prognathism may adapt to the new environment achieved with surgically corrected dentofacial structure, although the activities remain at lower levels as compared with the controls.     

Postoperative mandibular stability after orthognathic surgery in patients with mandibular protrusion and mandibular deviation

Skeletal stability and temporomandibular joint (TMJ) signs and symptoms were analyzed in 23 patients in whom mandibular protrusion and mandibular deviation had been corrected using bilateral sagittal split ramus osteotomy (BSSRO group, n = 10) and unilateral SSRO and intraoral vertical ramus osteotomy (USSRO+IVRO group, n = 13). Miniplate fixation was used in SSRO but no fixation was used in IVRO. The ratio of condylar bony change was 30.4% (7/23) and all condylar bony changes were seen on the deviated side. All preoperative signs and symptoms of TMJ disorders (4/13 patients in the USSRO+IVRO group and 2/10 patients in the BSSRO group) disappeared after surgery. Comparing the USSRO+IVRO group and the BSSRO group, in patients without condylar bony change, the mandible in both groups was stable anteriorly and horizontally after surgery, even though there was a larger horizontal mandibular movement in the USSRO+IVRO group during surgery. Comparing patients with condylar bony change versus no condylar bony change in the USSRO+IVRO group, postoperative horizontal mandibular displacement was significantly larger in the condylar bony change group than in the no condylar bony change group. These results support the idea that USSRO+IVRO can be useful in correcting mandibular deviation as well as improving signs and symptoms of TMJ disorders. However, it also seems important to be aware of the possibility of horizontal mandibular relapse in patients with condylar bony change.     

Changes in the facial soft-tissue profile after mandibular orthognathic surgery

Objectives

To investigate the correlation between soft- and hard-tissue changes after mandibular orthognathic surgery, to generate precise prognostic values for the esthetic treatment outcome of the facial profile.

Material and Methods

In this retrospective study, sagittal changes in the facial soft tissue profile in relation to surgical changes in hard structures after mandibular osteotomy were examined. The sample population included 144 reported adult patients aged 17–50 years who had received combined mandibular orthognathic surgery and orthodontic treatment at the Department of Orthodontics, Ludwig-Maximilians University of Munich, Germany. Both mandibular advancement and mandibular setback cases in monognathic and bignathic osteotomy procedures were included. All subjects had undergone rigid fixation. A cephalometric analysis of presurgical and postsurgical cephalograms was performed, and the correlations between hard-tissue and soft-tissue change ratios were evaluated using a bivariate linear regression analysis.

Results

The lower lip, represented by the landmark Labrale inferius (Li), followed the lower incisor (Ii) by 77%. The soft-tissue B-point (B’) followed the B-point (B) by 97% and the soft-tissue Pogonion (Pg’) followed the Pogonion (Pg) by 97% in a linear correlation.

Conclusion

The scatterplots show a distinct linear correlation and no significant difference in the direction of the movement. A wider spread for the lower lip (Li/Ii) indicates a lower predictability of the expected lip position, whereas a narrow spread of the chin values (B’/B and the Pg’/Pg) reveals a very good predictability of the postoperative chin position.

Clinical relevance

This study contributes valid data for the soft-tissue profile prediction in orthognathic surgery.

     

Changes in mandibular mobility after different procedures of orthognathic surgery.

A prospective study including 63 adult Class II and Class III patients was carried out in order to examine short- and long-term effects of four different treatment methods on mandibular mobility. The patients were treated either (Group A, control-group) orthodontically alone or (Group B) by a LeFort I-osteotomy, a (Group C) mandibular advancement or (Group D) a two-jaw surgery/mandibular set-back. In the surgery-groups (B, C, and D) maximum opening, protrusion and lateral excursions were measured 2 days pre-operatively (T0), and 3, 8, 14.5, and 25.5 months post-operatively (T1-T4). In the control-group (A) at T0 and T4 was measured, only. Significantly differing effects of the four treatment methods on mandibular mobility were detected. (A) Orthodontic treatment alone, (B) maxillary advancement by LeFort I osteotomy, and (D) two-jaw surgery/mandibular set-back osteotomy did not influence mandibular mobility permanently. Temporary decreases in groups B and D (P less than or equal to 0.05) were observed, however. In contrast, permanent reductions after (C) mandibular advancement took place (P less than or equal to 0.001). Longitudinal survey showed that in all surgery groups recoveries were limited to a short period of 3-14.5 months, depending on the movement. Surprisingly, a closer similarity between the LeFort-I group (B) and the two-jaw surgery group (D), rather than between the sagittal-split groups (C and D), was seen indicating that the problem of reduced mobility after orthognathic surgery can be limited to Class II therapy. It was concluded that in Class III therapy, the application of rigid fixation in combination with a method of maintaining condyle-position, thereby dispensing with maxillomandibular fixation, prevents permanent reductions in mobility and guarantees a rapid recovery to pre-operative mobility levels.     

Changes in the occlusal function of orthognathic patients with vertical malformations after combined orthodontic surgical therapy: a prospective clinical study

The aim of this study was to assess the changes in occlusal patterns during combined surgical and orthodontic therapy in patients with vertical jaw malformations. Twenty-six orthognathic patients (18 female, eight male; median age 25 years, interquartile range 11.5 years) and 10 control patients (five female, five male; median age 29.8 years, interquartile range 13.5 years) recruited from neutral configured patients attending the Department of Orthodontics, were investigated. Based on cephalometry, the patients were grouped into vertical skeletal configurations of either open, deep, or natural bite cases. Registrations of the occlusal contacts were taken using a digital occlusal sensor immediately before surgery and at 9 months after the surgical intervention. Before the intervention, open and deep bite patients showed significantly less efficient occlusal patterns than the untreated controls regarding total tooth contact (P < 0.001), time of occlusion (P = 0.002), occlusal asymmetry (P = 0.001), anterior tooth contact (P < 0.001), and posterior tooth contact (P < 0.001). After surgery, the parameters in the deep bite patients were similar to those in the controls; however, in open bite patients, total tooth contact (P = 0.003), occlusal asymmetry (P = 0.011), and posterior tooth contact (P = 0.035) differed significantly. In conclusion, combined orthodontic and surgical correction of vertical malocclusions was found to improve occlusal function in patients with deep bite to the level of controls.     

Changes in oropharyngeal airway and respiratory function during sleep after orthognathic surgery in patients with mandibular prognathism

The aim of this study was to examine the effects of mandibular setback surgery on pharyngeal airway space and respiratory function during sleep. The subjects were 22 patients in whom mandibular prognathism was corrected by bilateral sagittal split ramus osteotomy; either one jaw or two jaw surgery. Polysomnography was performed before surgery and 6 months after surgery, and the apnea hypopnea index (AHI) and arterial oxygen saturation during sleep were measured to assess respiratory function during sleep. Morphological changes were studied using cephalograms taken immediately before, a few days after and 6 months after surgery. As a control, 10 subjects without sleep-disordered breathing underwent the same examinations. AHI was not changed significantly after surgery, although two patients were diagnosed with mild obstructive sleep apnea (OSA) syndrome after surgery. They were not obese, but the amounts of mandibular setback at surgery were large. In conclusion, a large amount of mandibular setback might inhibit biological adaption and cause sleep-disordered breathing, and it might be better to consider maxillary advance or another technique that does not reduce the airway for patients with skeletal class III malocclusions who have large anteroposterior discrepancy and/or maxillary hypoplasia.     

Patients' perception of improvement after orthognathic surgery: pilot study

We aimed to find out what patients thought of their quality of life after they had had an orthognathic operation. Thirty-two patients returned three questionnaires and 15 were further interrogated by telephone. Preoperatively the patients mentioned mainly functional problems as a reason for asking for the operation, but expectation of aesthetic improvement was also an important factor. They were generally satisfied with the outcome of the operation. Postoperative improvement was mentioned in terms of chewing, appearance, headaches, and bullying. Patients felt more secure in company with other people postoperatively. We conclude that patients' perceptions after orthognathic operations were generally favourable but there is a need for improved information to patients during the treatment.     

Changes in masticatory function after orthognathic treatment in patients with mandibular prognathism.

Changes in masticatory function were measured in 27 patients in whom mandibular prognathism was corrected surgically. The mean value of masticatory efficiency before treatment was 46% of that of control subjects with normal occlusion. It improved, but remained at 60% of the control value postoperatively. Similar changes were seen in the number and area of occlusal contacts and the integrated muscle activities of the masseter and temporalis on the chewing side, but the postoperative improvement in masticatory efficiency was mainly the result of improvement in masseter activity. The mean values of masticatory cycle variables in the patient group did not differ significantly from those of the controls. Their preoperative mean coefficients of variation, which were significantly higher than those of the controls, decreased significantly postoperatively. These results suggest that the stability of masticatory rhythm was improved by orthognathic surgery.     

Changes in health-related quality of life after orthognathic surgery: a multicenter study

Clinical Oral Investigations - To evaluate changes in general and oral health-related quality of life (HRQoL) in patients with dentofacial deformity undergoing orthognathic surgery, and whether...     

Kinematic analysis of mandibular motion before and after orthognathic surgery for skeletal Class III malocclusion: A pilot study

Objectives: The aim of the study was to detect the changes in 3D mandibular motion after orthognathic surgery for skeletal Class III malocclusion.

Method: Using a 3D motion analyzer, free mandibular border movements were recorded in nine patients successfully treated for skeletal Class III malocclusion and in nine patients scheduled for orthognathic surgery. Data were compared using Mann–Whitney non-parametric U-test.

Results: The results showed no differences between the groups in the total amount of mouth opening, protrusion, and in lateral excursions, but the percentage of mandibular movement explained by condylar translation was significantly increased after surgery (20% vs. 23.6%). During opening, the post-surgery patients showed a more symmetrical mandibular interincisal point and condylar path than pre-surgery patients (p < 0.01).

Discussion: Patients treated with orthognathic surgery for skeletal Class III malocclusion recover a good and symmetric temporomandibular joint function.     

Increase in mandibular and chin projection with orthognathic surgery

Three groups of twelve patients, each of whom had a Class II, Division 1 malocclusion with a markedly convex facial profile and steep mandibular plane, were treated by orthodontic means and orthognathic surgery. One group had mandibular advancement, another had maxillary elevation, and the third had both surgical procedures combined, with genioplasties performed in some cases from each group. Changes were studied with the aid of lateral cephalometric headfilms taken just after surgery and from 5 to 105 months later. Horizontal changes in point B and pogonion after the follow-up period were 7.0 mm and 8.5 mm with mandibular surgery, 5.4 mm and 9.3 mm with maxillary surgery, and 10.7 mm and 16.4 mm with combined surgery. The amount of change is much larger than found with orthodontic or orthopedic treatment alone and makes possible the successful treatment of very difficult problems.     

The effect of orthognathic surgery on occlusal force

To investigate the effect of orthognathic surgery on occlusal force, such force was measured during maximum effort, chewing, and swallowing in 70 patients who had superior repositioning of the maxilla and/or mandibular advancement or setback. Larger changes in occlusal force than could be accounted for by the altered geometry were observed in all groups. Of 15 patients who had only superior repositioning of the maxilla, ten had greater than 20% increase in occlusal force, three had little change, and two showed a greater than 20% decrease. When the mandible was advanced, 11 of 34 patients had greater than 20% increase in maximum biting force, 11 had little or no change, and 12 had greater than 20% decrease. When the mandible was set back, six of the 21 patients had greater than 20% increase, nine had little or no change, and six had greater than 20% decrease. It appears that considerable change in bit force, which is not primarily related to jaw geometry, occurs after orthognathic surgery.     

Features of occlusal state in female Japanese patients with migraine: a case-controlled study

Objectives: The prevalence rate of migraines is 8.4%; it is mostly diagnosed in women at 20s to 40s, and is known to cause major physical and mental disruption to daily life. This study was conducted on women aged between their 20s and 40s, in order to investigate the possible differences in the features of the occlusal state between a migraine and a non-migraine (control) group.

Methods: Age-matched female patients with migraine (n = 60) diagnosed by headache specialists and healthy controls (n = 57) were enrolled. Dental casts were used to evaluate some features.

Results: The maxillary and mandibular dentition casts from the migraine group showed significantly characteristic findings in their Angle’s classification, overjet, and deviation in the anterior tooth midline, compared to the control group.

Discussion: The results relating occlusal state to both tension-related headaches and migraines, which have different pathogeneses, suggest the possibility of dental intervention to improve the symptoms of primary headaches.     

Changes in occlusal force and occlusal contact area after active orthodontic treatment: a pilot study using pressure-sensitive sheets

The aim of this study was to investigate functional changes in occlusion during retention. Data on occlusal force (OcFr) and occlusal contact area (OcAr) was obtained using the pressure-sensitive sheet, from a treated group (20 female patients) who had had four premolar extractions and treatment with standard edgewise appliances, and a control sample who matched the treated group of retainer for sex, age and Angle classification at 1 year after removal. A repeated measures analysis of variance showed that the mean values of total OcFr and OcAr in the treatment group gradually increased during retention and were 669.3 N and 15.1 mm2, respectively, at 1 year after removal of retainer. The increases of OcFr and OcAr were larger in the molar region, especially at the second molar. At 1 year after removal of retainer, OcFr and OcAr in the second molar were significantly larger in the treatment group than in the control sample, and a similar distribution pattern of OcFr and OcAr to those in normal occlusion was seen. These results suggested that balanced OcFr and OcAr might be obtained during and after retention, due to the settling of molars that had been discluded by active orthodontic treatment.     

Accuracy of perioperative mandibular positions in orthognathic surgery

Mandibular position is an important parameter used for the diagnosis of dentofacial deformities, as well as for orthognathic surgery planning and execution. Centric relation (anterior and superior relationship of the mandibular condyles interposed by the thinnest portion of their disks against the articular eminencies), centric occlusion (when lower teeth contact upper teeth at centric relation), and maximal intercuspation (complete interdigitation of lower and upper teeth) are not often addressed as factors that influence the results of orthognathic surgery, although these relationships are critical to ensure accuracy during the surgery. The present study assessed occlusal measurements taken before and after the induction of general anaesthesia from consecutive orthognathic surgery subjects. The variables assessed included the differences between these occlusal measurements, patient age, gender, type of deformity, and type of proposed orthognathic surgical procedure. The results demonstrated statistically significant differences for mandibular retrusion from maximal intercuspation to centric occlusion position, whereas the mandible appeared not to change significantly from centric occlusion after the induction of general anaesthesia. Patient age and the type of deformity appeared to influence the results. While in most instances centric occlusion can be adequately reproduced under general anaesthesia, for some specific orthognathic cases more accurate results might be obtained if the mandible-first sequence is used.