An evaluation of the changes in maxillary pulpal blood flow associated with orthognathic surgery.
The objective of this study was to evaluate the use of the Laser Doppler Flowmeter (LDF) in the measurement of pulpal blood flow following orthognathic surgery and to conduct an initial study of the effects of a Le Fort I osteotomy on the pulpal blood flow of the maxillary central incisors. The design consisted of a preliminary prospective controlled consecutive clinical trial undertaken at the Orthodontic Clinic, University Dental Hospital NHS Trust, Wales, 1994. The study group consisted of 15 consecutive patients who were to receive a standard advancement Le Fort I osteotomy. Seven patients who were to undergo a mandibular advancement only acted as a control. A further 20 separate patients participated in a study for the assessment of measurement error. The blood flow in relative perfusion unit v. time, was measured using a Laser Doppler Flowmeter. Measurement error for flowmeter recordings with hand-held application and custom-made splint support showed no consistent difference or significant random variation between the two methods for holding the probe against the teeth (pooled S.D. of reproducibility 1/1 = 1.91/1.39 for custom splint location as opposed to 0.96/1.07 for hand-held/fixed bracket location). For the surgical patients under investigation no significant differences for maxillary pulpal blood flow were found in the control group (mandibular osteotomy) over time. However, in the maxillary osteotomy patients there was a tendency for an initial rise in the maxillary perfusion post-surgery as measured at the central incisor pulps, followed by an overall reduction at 6 months. As an example, the mean value for the upper right central showed a significant increase in blood flow during the immediate post-operative period (P < 0.05), but at 6 months after surgery demonstrated a statistically significant overall reduction in comparison with the presurgical reading (P < 0.001). The laser Doppler flowmeter is not an easy instrument to use in the clinical assessment of pulpal blood flow. However, it would appear from these longitudinal series of readings, taken over a 6-month period on 15 patients, that the maxillary perfusion recorded at the central incisor pulps may be permanently affected in many Le Fort I osteotomy patients. For patients that already have a prejudiced blood supply this could lead to devitalization and discoloration of incisors. It is not known if this affect on the perfusion of the pulp continues beyond 6 months post-surgery. (+info)
Intra-operative blood loss and operating time in orthognathic surgery using induced hypotensive general anaesthesia: prospective study.
We investigated the average operating time and extent of intra-operative blood loss in orthognathic surgeries performed using induced hypotensive general anaesthesia, with the intention of devising a practical guideline for blood unit preparation for these procedures. We prospectively studied 32 Chinese patients undergoing surgery to correct dentofacial deformities at a public hospital in Hong Kong from 1 December 1997 to 1 December 1998. Most patients (72. 4%) needed double-jaw surgery. The mean estimated blood loss was approximately 617.6 mL. The blood loss during simple Le Fort I osteotomies was about half that of multiple segmentalised osteotomies. For mandibular ramus osteotomies, the mean blood loss and operating time for were approximately 280 mL and 2 hours, respectively; for anterior mandibular osteotomies, the corresponding values were 171.3 mL and 1 hour 13 minutes. The average drop in the haematocrit value was 15.4%, and the crossmatch to transfusion ratio was 29. A bivariate correlation test between the blood loss and operating time gave a strong correlation (P<0.01), as did blood loss with a drop in haematocrit value (P<0.01). Orthognathic surgeries are thus safe and predictable in terms of intra-operative blood loss and operating time, and a 'type, screen, and save' policy for blood unit preparation is more appropriate than a 'crossmatch' policy. (+info)
Temporomandibular dysfunction in patients treated with orthodontics in combination with orthognathic surgery.
Fifty-two patients with malocclusions underwent orthodontic treatment in combination with orthognathic surgery involving a Le Fort I and/or sagittal split osteotomy. Approximately 5 years after surgery, the patients were examined for signs and symptoms of temporomandibular disorders (TMD). The frequencies were found to be low in comparison with epidemiological studies in this field. The aesthetic outcome and chewing ability were improved in most patients (about 80 per cent). Some of the patients had reported recurrent and daily headaches before treatment. At examination, only two patients had reported having a headache once or twice a week, while all the others suffered from headaches less often or had no headache at all. Eighty-three per cent of the patients reported that they would be prepared to undergo the orthodontic/surgical treatment again with their present knowledge of the procedure. This study shows that orthodontic/surgical treatment of malocclusions not only has a beneficial effect on the aesthetic appearance and chewing ability, but also results in an improvement in signs and symptoms of TMD, including headaches. (+info)
Open bite: stability after bimaxillary surgery--2-year treatment outcomes in 58 patients.
Stability after bimaxillary surgery to correct open bite malocclusion and mandibular retrognathism was evaluated on lateral cephalograms before surgery, 8 weeks post-operatively, and after 2 years. The 58 consecutive patients were treated to a normal occlusion and good facial aesthetics. Treatment included the orthodontic alignment of teeth by maxillary and mandibular fixed appliances, Le Fort I osteotomy, and bilateral sagittal split ramus osteotomy. Twenty-six patients also had a genioplasty. Intra-osseous wires or bicortical screws were used for fixation. Twenty-three patients had maxillo-mandibular fixation (MMF) for 8 weeks or more, six for 4-7 weeks, 14 for 1-3 weeks, and 15 had no fixation. At follow-up 2 years later, the maxilla remained unchanged and the mandible had rotated on average 1.4 degrees posteriorly. Seventeen patients had an open bite. Among them, eight patients had undergone segmental osteotomies. The relapse was mainly due to incisor proclination. The most stabile overbite was found in the group with no MMF after surgery. (+info)
A validation of two orthognathic model surgery techniques.
In order to create an evidence-based orthognathic surgery planning protocol, an investigation of two popular model surgery techniques, the Lockwood keyspacer and the Eastman anatomically-orientated system was carried. This determined (a) the accuracy of positioning of the maxillary cast according to the prescribed treatment plan and (b) the relocation of the maxilla after a simulated Le Fort I down fracture osteotomy using the intermediate wafer as a guide. Fifteen patients-five Class II division 1, five Class II division 2, and five Class III-were included in the study. All the measurements were taken with Erickson's vertically mounted electronic caliper and variations from the treatment plan were analysed. The mean model surgery positioning errors +/- SD (mm) were: (i) vertical plane-Lockwood -0*8 +/- 1*6 and Eastman 0*00 +/- 1*0 (P = 0*0001); (ii) anteroposterior plane-Lockwood 1*2 +/- 1*8 and Eastman -0*1 +/- 1*4 (P = 0*05); and (iii) transverse plane-Lockwood 0*9 +/- 0*9 and Eastman 1*0 +/- 0*9 (P = 0*34). After the simulated osteotomy, the mean errors +/- SD were: (i) vertical plane-Lockwood -0*5 +/- 1*5 and Eastman 0*3 +/- 1*1 (P = 0*001); (ii) in anteroposterior plane-Lockwood 0*8 +/- 2*0 and Eastman 0*7 +/- 1*0 (P = 0*89); and (iii) transverse plane-Lockwood 0*8 +/- 0*6 and Eastman 0*7 +/- 0*5 (P = 0*83). The Eastman technique was relatively better especially in the vertical plane. The variations from the treatment plan were on the whole anatomically small, but in some cases could be clinically significant. (+info)
Skeletal and dento-alveolar stability after surgical-orthodontic treatment of anterior open bite: a retrospective study.
The aim of this investigation was to assess skeletal and dento-alveolar stability after surgical-orthodontic correction of skeletal anterior open bite treated by maxillary intrusion (group A) versus extrusion (group B). The cephalometric records of 49 adult anterior open bite patients (group A: n = 38, group B: n = 11), treated by the same maxillofacial surgeon, were examined at different timepoints, i.e. at the start of the orthodontic treatment (T1), before surgery (T2), immediately after surgery (T3), early post-operatively (+/- 20 weeks, T4) and one year post-operatively (T5). A bimaxillary operation was performed in 31 of the patients in group A and in six in group B. Rigid internal fixation was standard. If maxillary expansion was necessary, surgically assisted rapid palatal expansion (SRPE) was performed at least 9 months before the Le Fort I osteotomy. Forty-five patients received combined surgical and orthodontic treatment. The surgical open bite reduction (A, mean 3.9 mm; B, mean 7.7 mm) and the increase of overbite (A, mean 2.4 mm; B, mean 2.7 mm), remained stable one year post-operatively. SNA (T2-T3), showed a high tendency for relapse. The clockwise rotation of the palatal plane (1.7 degrees; T2-T3), relapsed completely within the first post-operative year. Anterior facial height reduction (A, mean -5.5 mm; B, mean -0.8 mm) occurred at the time of surgery. It can be concluded that open bite patients, treated by posterior Le Fort I impaction as well as with anterior extrusion, with or without an additional bilateral sagittal split osteotomy (BSSO), one year post-surgery, exhibit relatively good clinical dental and skeletal stability. (+info)
Post-operative stability of the maxilla treated with Le Fort I and horseshoe osteotomies in bimaxillary surgery.
In this study, the post-operative change of the maxilla in six non-cleft patients who underwent combination (Le Fort I and horseshoe) osteotomy for superior repositioning of the maxilla was investigated. In all patients, the maxilla was first osteotomized and fixed with four Luhr plates. No iliac bone graft was applied to the maxilla. A bilateral sagittal split ramus osteotomy of the mandible (BSSRO) was then carried out and titanium screw fixation was performed. No maxillo-mandibular fixation (MMF) with stainless steel wire was used post-operatively in any patient. Lateral cephalograms were obtained pre-operatively, 5 days post-operatively, and 3, 6, and 12 months after surgery. The changes in anterior nasal spine (ANS), point A, upper incisor (U1), and point of maxillary tuberosity (PMT) were examined. The maxillae in the six subjects were repositioned nearly in their planned positions during surgery and no significant post-operative changes in the examined points of the maxilla were found. These results suggest that a combination of a Le Fort I and horseshoe osteotomy is a useful technique for reliable superior repositioning of the maxilla. The post-operative change in the maxilla using this combination osteotomy is comparatively stable. (+info)
Dental tipping and rotation immediately after surgically assisted rapid palatal expansion.
The purpose of this investigation was to evaluate the effects of dental tipping and rotation immediately after surgically assisted rapid palatal expansion (SARPE). Fourteen patients (10 females, four males; mean age 25.6 years) who required a SARPE procedure were available for this study. A palatal expander appliance was cemented on four abutment teeth (first premolars and first molars) of each patient 1 week prior to surgery. Maxillary study models were taken before surgery and 2-3 weeks after full expansion (7 mm). Each model was trimmed to have the base parallel to its occlusal plane. From an occlusal view, measurements were made to determine if the abutment teeth underwent rotation from SARPE. From a postero-anterior view, the abutment teeth were examined for any tipping effect due to SARPE. The results showed that from pre- to post-expansion, the two first premolars displayed 2.32 +/- 8.29 degrees of mesiobuccal rotation (P > 0.05) and the two first molars displayed 3.09 +/- 5.89 degrees of mesiobuccal rotation (P > 0.05). Each first premolar showed 6.48 +/- 2.29 degrees of buccal tipping (P < 0.05) and each first molar 7.04 +/- 4.58 degrees of buccal tipping (P < 0.05). SARPE induced a slight mesiobuccal rotation (P > 0.05) and significant buccal tipping of the first premolars and the first molars (P < 0.05). Some overexpansion is suggested to counteract the relapse effect of buccal tipping of the posterior teeth that takes place during SARPE. (+info)