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Biomedical subjects

P D Waite

Publications and source records attributed to P D Waite.

At least 19 recordsLinked to original sources
PubMed2001

Soft tissue changes of the upper lip associated with maxillary advancement in obstructive sleep apnea patients.

PURPOSE: This retrospective study evaluated the horizontal and vertical soft tissue changes that occur with maxillary advancement surgery with a Le Fort I osteotomy with concomitant anatomic reorientation of the nasolabial musculature. SUBJECTS AND METHODS: Fifteen OSA patients who underwent maxillary advancement with a Le Fort I osteotomy without adjunctive nasal soft tissue procedures were studied after a minimum of 8 months of follow-up. The V-Y technique was used to close the maxillary vestibular incision. Only cases with minimal vertical movement (< 3.5 mm) in which no orthodontics were used were included. The average maxillary advancement was 8.0 +/- 2.5 mm, measured at the upper incisor (UPI) and the average vertical movement was 0.7 +/- 1.8 mm. The horizontal and vertical soft tissue change in subnasale (SN), labrale superiorus (LS), superior stomion (SS), nasal tip (NT), nasolabial angle (NLA), and lip length were measured in each patient and correlated with hard tissue measurements at anterior nasal spine (ANS) and UPI. The effect of lip thickness on these soft tissue changes also was evaluated. RESULTS: Using mean data, the horizontal soft-to-hard-tissue ratio for LS to UPI was 0.80:1, with a concomitant vertical (superior) soft tissue change to hard tissue advancement of 0.16:1. Lip length did not change significantly. All patients except 1 showed a slight decrease in nasolabial angle. The average decrease was 5 (range, -10 to +7 ). There was no statistically significant correlation between the degree of change in NLA and the amount of maxillary advancement. CONCLUSION: This study showed that advancement of the maxilla when controlling vertical movement resulted in the a hard-to-soft-tissue ratio of LS:UPI of 0.80:1. NLA did not change significantly.

Adult↗
PubMed2001

Strength analysis of Le Fort I osteotomy fixation: titanium versus resorbable plates.

PURPOSE: The purpose of this study was to compare the biomechanical characteristics of metallic and polymeric fixation systems using a 3-dimensional skull model to simulate clinical conditions of maxillary advancement and loading. MATERIAL AND METHODS: Standard titanium, prebent titanium, and resorbable plates and mesh were applied to surgically altered polyurethane skulls. The constructs were loaded using an Instron machine (Instron Inc, Canton, MA) in anterior-posterior (AP) and inferior-superior (IS) directions. The load displacement, load to failure, and deformation magnitudes and modes of failure were recorded. Statistical studies included analysis of variance (ANOVA) at P <.05. RESULTS: Elastic stiffness was different among groups in the AP direction, but no significant difference was found in the IS direction. The IS loading direction load displacement (stiffness) was significantly greater than that on AP loading. The maximum load for permanent deformation was larger in the AP direction, while the maximum load for breaking was larger in the IS direction. CONCLUSION: The overall evaluation of the model and test analyses supported the relative value of this in vitro system and study procedure. All systems showed load capacity magnitudes above 285 N (64 lbs) and more elastic resistance in the IS direction. The resorbable systems showed lower elastic stiffness compared with the titanium systems, but they appear to be adequate for fixation and withstanding the forces of mastication.

Absorbable Implants↗
PubMed1998

Surgical management of impacted third molars.

Teeth may become impacted when they fail to erupt or develop into the proper functional location. As such, impacted teeth are considered nonfunctional, abnormal, and pathological. The mandibular third molar is the most common tooth to become impacted. The cause of impacted third molars is thought to be inadequate space. Several studies indicate that a change from a coarse, attritive diet to a modern, refined diet has lead to an increased incidence of impacted teeth. Interproximal attrition allows for greater mesial migration of teeth and space for third molar teeth. Teeth that fail to attain a functional position may be pathological and should be considered for removal. The indications for removing impacted teeth can be divided into those of acute or chronic pathology. Impacted third molars are often associated with pain, infection, cyst formation, benign tumors, root resorption, bone loss, periodontal disease, and caries. The decision to surgically remove impacted third molars is often unclear. There are no absolute treatment protocols established. The dentist must consider a variety of factors and make an informed decision with the patient. Most experienced clinicians combine objective data and common sense to arrive at a logical treatment plan. The purpose of this article is to discuss factors related to impacted teeth and help the orthodontist understand the general management of impacted third molars. The decision for surgery will be assisted by an understanding of all of the risk factors associated with impacted teeth and presenting the options to the patient.

Decision Trees↗
PubMed1998

A case report. Chondromatosis of the temporomandibular joint.

Synovial chondromatosis is a rare pathological condition that usually affects large joints but can affect the temporomandibular joint. The disease typically manifests itself with signs and symptoms similar to internal derangement. The disease is characterized by free-floating or attached cartilaginous bodies in the joint space. In this article, the authors present a case of synovial chondromatosis and discuss its pathological process. They also discuss diagnostic approaches and current treatment.

Adult↗
PubMed1996

The stability of maxillary advancement using Le Fort I osteotomy with and without genial bone grafting.

The purpose of this study was to determine whether better stability is achieved with genial bone grafts and four-plate rigid fixation for large advancement Le Fort I osteotomies of the maxilla than with nongrafted osteotomies. We analyzed radiographic data on 22 patients with obstructive sleep apnea syndrome. All patients underwent Le Fort I osteotomy for maxillary advancement, 11 patients without bone grafts and 11 patients with bone grafts harvested from the mandibular symphyseal area. Bilateral sagittal split advancement osteotomies and genial tubercle advancements were also performed in all patients. Patients in the genial bone-grafted group had a mean advancement (surgical change) of 9.7 mm and a mean relapse (postsurgical change) of 0.7 mm (7%). Patients who had rigid fixation alone had a mean advancement of 10 mm and a mean relapse of 1.8 mm (18%). It is concluded that the stability with genial bone grafts to the lateral wall of the maxilla with four-plate rigid fixation was better than in the nongrafted group.

Adult↗
PubMed1996

Bone grafting for the alveolar cleft defect.

Seventy-five percent of all cleft lip and palate patients have osseous defects of the alveolus. Bone grafting of this defect normalizes facial and dental function. Failure to reconstruct the osseous deformity may result in oronasal fistula, fluid reflux, speech pathology, anteroposterior deficiency of the maxilla, transverse deficiency of the maxilla, lack of bone support for the incisors and cuspids, dental crowding, and facial asymmetry. Bone grafting unifies the maxilla and is best done after the majority of facial growth is complete and the secondary dentition is erupting. This is known as secondary bone grafting and yields the best results. The dentofacial deformity of cleft lip and palate is best managed by coordination of dental development, surgery and orthodontics.

Adolescent↗
PubMed1995

Maxillomandibular advancement surgery in obstructive sleep apnea syndrome patients: long-term surgical stability.

PURPOSE: This study examined the long-term skeletal stability of relatively large maxillomandibular advancement surgery in the treatment of obstructive sleep apnea syndrome (OSAS). MATERIALS AND METHODS: The presurgical, immediate (< 1 month), and long-term (> 12 months) postsurgical cephalometric radiographs of 19 patients undergoing maxillomandibular advancement with simultaneous genioplasty for OSAS were studied. The cephalometric measurements and calculations were performed using a commercial cephalometric software. RESULTS: Maxillary and mandibular advancement seems to be stable in the horizontal and vertical planes over the long term. There was no significant correlation between the amount of surgical advancement and the amount of postsurgical instability, with the exception of gonion in the vertical plane. CONCLUSION: The results from this study indicate that large surgical advancements in OSAS patients result in relatively stable repositioning of the maxilla and mandible over the long term.

Bone Plates↗
PubMed1994

Autologous TMJ disk replacement.

Several techniques have been advocated for replacement of displaced or diseased temporomandibular joint disks. Techniques are reviewed and the author's experience in managing this complex problem is presented.

Arthroplasty↗
PubMed1993

Long-term skeletal stability after rigid fixation of Le Fort I osteotomies with advancements.

The purpose of this retrospective study was to evaluate relapse, comparing large and small maxillary advancements with four-plate rigid fixation and without bone grafting. All patients had obstructive sleep apnea, and underwent bimaxillary surgery. Standardized cephalometric analysis by two separate examiners was performed on serial radiographs of 20 patients immediately before surgery, and at 1 week and at least 6 months postoperatively (mean 18.5 months). The group was divided into three subsets to determine whether the magnitude of maxillary advancement correlated with the magnitude of relapse. In group 1 (< or = 6 mm, n = 4), the average advancement was 4.7 +/- 0.8 mm, with a mean relapse of 0 +/- 0.6 mm. In group 2 (7-9 mm, n = 9), the average advancement was 8.2 mm +/- 0.9, with a mean relapse of 0.7 +/- 1.5 mm. In group 3 (> or = 10 mm, n = 7), the mean advancement was 12.3 +/- 2.8 mm, with a mean relapse of 1.9 +/- 1.8 mm. There was no statistical difference in the measured relapse among the groups.

Adult↗
PubMed1992

In vitro strength analysis of sagittal split osteotomy fixation: noncompression monocortical plates versus bicortical position screws.

An in vitro study using bovine ribs was performed to compare the strength of monocortical plates with bicortical position screws. An osteotomy was created to simulate a sagittal split and a 5-mm bone gap was produced. Four study groups were created: screw nongap, screw with gap, plate nongap, and plate with gap. Parameters of strength were analyzed by elastic deformation, stiffness ratio, permanent deformation, and breaking load. The results showed that monocortical plate fixation in bovine ribs provides less rigidity and is more susceptible to deformation than is bicortical position screw fixation.

Alloys↗
PubMed1991

Open reduction and internal rigid fixation of subcondylar fractures via an intraoral approach.

Extraoral open reduction and rigid fixation of mandibular subcondylar fractures is controversial among surgeons. An intraoral approach with a percutaneous trocar and miniplates demonstrated satisfactory reduction. This technique can be more easily performed than a preauricular or submandibular incision, and risk of facial nerve damage is diminished. Early function with proper vertical dimension was restored with minimal postoperative morbidity.

Adult↗