Biomedical subjects

M Y Mommaerts

Publications and source records attributed to M Y Mommaerts.

At least 37 records · Page 2Linked to original sources

PubMed1999

Six year's experience with the zygomatic "sandwich" osteotomy for correction of malar deficiency.

PURPOSE: This study discusses the rationale, modifications, and complications of an osteotomy technique used to increase malar projection. PATIENTS AND METHODS: Seventy "sandwich" zygomatic osteotomies were performed in a 6-year period. Hydroxyapatite (HA) blocks were used to stabilize the anterolateral rotation of the zygomatic body in 44 osteotomies, calcium carbonate blocks were used in 23, calvarial bone grafts in three, a piece of bovine cartilage in one, and a bone graft from a chin ostectomy procedure combined with mesh osteosynthesis in one procedure. Fifty-six zygomatic osteotomies were combined with Le Fort I-type osteotomies (eight with a midline split). Nineteen zygomatic osteotomies were performed simultaneously with a Le Fort I-type osteotomy and a rhinoplasty with lateral osteotomies. RESULTS: The increase of malar projection and the stability of the procedure could not be measured on conventional three-plane cephalograms. However, patient's and surgeon's satisfaction were high and remained so during the follow-up period (maximum, 6.5 years; minimum, 6 months). Three patients developed maxillary sinusitis. In two of them, this was clearly related to fragmentation of an HA block. A Treacher-Collins patient developed a chronic fistula in the upper vestibule, caused by leakage of infraorbitally placed HA granules. In two cases, a fracture of the zygomatic arch occurred. Osteosynthesis was performed in one of them. CONCLUSION: With proper technique and care not to fracture the interpositional HA block, complications are rare. The procedure is expedient and provides predictable and stable correction of malar deficiency.

Adolescent↗

PubMed1999

Transpalatal distraction as a method of maxillary expansion.

Conventional devices used for surgically assisted rapid palatal expansion are tooth-borne. Dental fixation entails a number of possible drawbacks such as loss of anchorage, skeletal relapse during and after the expansion period, cortical fenestration and buccal root resorption. A bone-borne titanium device with interchangeable expansion modules, used with a callous distraction policy, is presented.

Anesthesia, General↗

PubMed1999

Proximal segment position after distraction with the MD-DOS device.

We investigated cephalometrically the movement of the proximal segment in the sagittal plane in patients treated with distraction (MD-DOS device) for mandibular lengthening. The proximal segment was anteriorly rotated, whilst the distal segment was posteriorly rotated after the lengthening procedure. Thus the angle of the jaw was advanced half the distance of the advancement of the distal segment. One possible reason for the anterior rotation of 3.3 degrees on average is the repositioning of the proximal segment during application of the anterior fixation unit in the cases where mobilization was complete. Another more plausible reason is the anterior pull by the masticatory muscles and elastic bands being greater than the reactive distraction vector component in concert with a flexible telescopic distraction module and a single posterior screw anchorage. The positional movements of both distal and proximal segments were similar to those observed after mandibular advancement with bilateral sagittal split osteotomies.

Adolescent↗

PubMed1999

The nasal frame osteotomy: technical note.

In the practice of orthognathic surgery, a patient presenting with a gummy smile and lip incompetence is readily diagnosed as having vertical maxillary excess, and a maxillary impaction osteotomy is usually the proposed treatment. If a short nose, an arched and upwardly displaced upper lip, and a broad face accompany these 2 features, nasal lengthening and caudal repositioning of the central portion of the upper lip by a nasal frame osteotomy should be considered instead. The technique of the nasal "frame" osteotomy, which was used in 1 patient with a 4-year follow-up, is described.

Adolescent↗

PubMed1998

Prediction of mandibular autorotation.

PURPOSE: The purpose of this investigation was to test the hypothesis that the mandible rotates around the same point during maxillary impaction surgery as during initial jaw opening. This point, called the center of mandibular autorotation (CAR), could then be used to predict mandibular position and to decide whether only maxillary impaction would be needed to correct the occlusion and the facial profile. PATIENTS AND METHODS: Preoperatively, two lateral cephalograms were obtained from a consecutive series of 20 patients who underwent maxillary impaction without concomitant mandibular ramus osteotomy. One cephalogram was taken with the mandible in centric relation using a wax bite wafer and another with a jaw opening of 10 mm using a fabricated acrylic bite block with the mandible manipulated to its most retruded position. The CAR was calculated before and after jaw opening using the Rouleaux method on the lower incisor and gonion point. A third lateral cephalogram was taken within 2 days postoperatively. The postoperative lower incisal point was then transferred to the first cephalogram using cranial base superimposition. RESULTS: When the preoperative and postoperative distances between CAR and incisal point were compared, there was no significant difference between these distances, proving the hypothesis. CONCLUSIONS: The method used is a practical and precise way to determine the center of mandibular autorotation on an individual basis. The center of rotation during initial jaw opening is the same as during impaction surgery.

Acrylic Resins↗

PubMed1998

Orthognathic surgery: patients' subjective findings with focus on the temporomandibular joint.

Two hundred and ninety-six patients who underwent various orthognathic surgery procedures were questioned, a minimum of 1 year postoperatively, on their overall subjective findings. Patient satisfaction, willingness to resubmit to surgery, self-confidence and subjective changes in their temporomandibular joints (TMJ) function and masticatory efficiency were evaluated. 87% would undergo the combined surgical-orthodontic treatment again. Self-confidence improved in 77% of the patients. There was a subjective improvement in TMJ function in 40% of the patients and a worsening in 11%; masticatory function was improved in 41% and worsened in 7% of the patients.

Adolescent↗

PubMed1998

[Mandibular distraction using a dynamic osteosynthesis system: MD-DOS. Concepts and surgical technic].

MD-DOS (mandibular distraction with a dynamic osteosynthesis system) is an intra-oral mandibular distractor that can be placed via the oral route, enabling application under local anesthesia. The aim of the article is to describe the technical-surgical aspects of the treatment concept, based on an initial experience of 35 cases. The device is characterised by a single horizontal posterior fixation screw-implant, a vertical hinge that copes with the lateral force vector in the condyles, a telescopic distraction module, and an anterior fixation unit that is fixed with monocortical screws. The main indication was mandibular lengthening in Angle Class II, deep bite cases. The third molars could be removed in the same session. Of importance was the horizontal placement of the posterior fixation unit (PFU), together with the distraction module, in order not to interfere with lateral jaw movements and with the lower sulcus. Equally important was the use of at least one 7.5 mm long osteosynthesis screw together with at least three 5.5 mm screws. Near complete mobilisation of the segments, firmly blocking the posterior fixation unit with the vertical hinge in a perpendicular position, and placing MD-DOS as close as possible to the dental arch, were also important parameters for success.

Anesthesia, Dental↗

PubMed1998

Horizontal anchorage in the ascending ramus--a technical note.

The ascending ramus provides a volume of bone that can receive horizontal screws of large sizes in the retromolar area, between the internal and external oblique lines. This area is not prone to disuse resorption and the only vital structure to consider is the neurovascular bundle. In this article two systems that make use of this anatomic opportunity are presented. One is an intraoral distractor, used for mandibular lengthening by gradual distraction. The other is a screw anchor that provides absolute anchorage for orthodontic tooth movement.

Adolescent↗

PubMed1997

High labial incisions for genioplasty.

Clinical experience in genioplasty has shown that high labial incisions heal with fewer scar bands than conventional deep labial incisions. In a prospective randomized trial, we compared 18 high labial curvilinear incisions with 27 high labial W-shaped ('royal') incisions for access and visibility during chin osteotomy. Both incisions were 3 cm wide. Maximal incision lengthening between two skin hooks was recorded with a ruler before closure, and there was no significant difference between the two. The maximum wound area between three skin hooks was photographed and computed, and showed a mean difference of 188.75 mm2 (t-test, P < 0.001), which corroborated the clinical findings that access and visibility were superior in the W-shaped incision group. Complications were few in both groups. We now use the high labial royal incision about 3.5 cm wide, with 90 degrees limb angle for complicated chin osteotomies and ostectomies. A smaller curvilinear high labial incision is used for simple advancement osteotomies.

Adult↗

PubMed1997

Reconstruction of the severely resorbed maxilla with a combination of sinus augmentation, onlay bone grafting, and implants.

PURPOSE: A new method of reconstruction of the atrophic maxilla by combining a bilateral sinus floor elevation and cancellous bone graft with buccal and labial onlay graft using L-shaped corticocancellous blocks from the posterior iliac crest is presented. PATIENTS AND METHODS: Seventeen patients were treated with this procedure. One hundred one IMZ implants were placed in 14 patients, and 22 Brånemark implants were placed in three patients. Patients were observed for 6 months after prosthetic rehabilitation. RESULTS: All patients were fully rehabilitated with fixed bridges except one, who preferred an overdenture. Only two implants were lost at the time of the abutment connection. Some bone resorption was seen around six implants. The success rate with this procedure was 92.7% 6 months after prosthetic rehabilitation if implants with bone resorption were considered failures. CONCLUSIONS: These preliminary results indicate that this surgical procedure is suitable for reconstruction of most atrophic maxillas.

Adult↗

PubMed1997

Reliability and validity of a backlighted digitizer when used for craniofacial measurements.

In this study the precision and validity of digitized measurements were tested for a specific, commercially available, backlighted digitizer. The tests were based on the repeated and systematic recordings of equally spaced points on a printed millimeter grid and on the repeated recordings of selected points on radiographic duplicating film and tracing acetate, with and without backlighting. Cursor and carrier position relative to the tablet, and tablet position relative to the monitor, proved to be important. The backlighting produced systematic bias due to the heating effect on both the duplicating film and the tracing acetate.

Analog-Digital Conversion↗

PubMed1997

An intra-operative technical aid to miniplating of mandibular fractures by fracture segment apposition.

Internal plate osteosynthesis and lag-screw osteosynthesis are currently the preferred methods of fixation in the treatment of mandibular fractures. Rigid internal fixation (RIF) provides for functionally stable immobilization of the segments, avoiding the need for postoperative intermaxillary fixation (IMF) by "dental wiring" in the majority of cases. Reduction and fixation can be provided by so-called compression plates (type AO/ASIF). Non compressive mini-plates are more extensively used, however, because their size and malleability facilitate their transoral application. Peroperative problems may arise with the anatomical reduction of the fragments. We present a simple fracture reduction-compression technique that can be used in combination with either compression and non-compression mini-plate fixation. Its use can be extended to reduction and fixation in selected areas of difficult surgical access.

Bone Plates↗

PubMed1997

The effect of the subspinal Le Fort I-type osteotomy on interalar rim width.

The postoperative increase in interalar rim width was measured in two groups undergoing Le Fort I impaction or advancement. In the control group, 19 patients with a conventional osteotomy, an absorbable alar cinch suture, and V-Y closure were followed for 20 months on average. In the experimental group, 12 patients with a "subspinal" Le Fort I osteotomy (without alar cinch or V-Y closure) were followed for 15 months on average. Interalar rim width was measured with a slide gauge preoperatively, at several times during surgery, and at the 6-month and late follow-up appointments. At surgery, the alar cinch suture decreased the interalar rim width by 50% in the control group. Still, after extubation, there was no statistical difference between groups. At the 6-month follow-up measurement, the interalar rim width was significantly (1.92 mm) smaller in the subspinal group. At the late follow-up, this difference had decreased by a mean of 0.61 mm.

Absorption↗

PubMed1996

Use of fibrin glue in lower blepharoplasties.

This prospective study investigates the long-term appearance of the scar following closure of lower blepharoplasty incisions with the fibrin adhesive Tissucol compared with the usual subciliary suturing. Eighteen eyelids closed with fibrin adhesive were compared with 12 eyelids where a 5-0 running suture was used for closure and to 10 eyelids that did not undergo surgery. The measurement team consisted of a panel, blind to patients and technique, that scored the scar morphology on a scale of 1-4. The Dunn test showed no difference between the group treated with the tissue adhesive and the group with conventional subciliary closure. There was a difference between the Tissucol treated group and the control group (P < 0.01). The surgical technique and the advantages in lower lid incision closure are discussed.

Adipose Tissue↗

PubMed1996

Interactive simulation of cranial surgery in a computer aided design environment.

Accurate pre-surgical planning is a prerequisite for successful craniofacial surgery. This paper introduces a simulation system developed in a computer aided design (CAD) environment, where a 3-D mathematical model of the skull is entered. The architecture of the program yields a flexible and easy-to-use system that allows the simulation of surgery on the wire frame image of the model. Possible actions simulated are osteotomy, bending, rotation, translation and removal. Numerical values for anatomical distances and the intracranial volume are easily calculated. Information on the techniques used and the numerical data resulting from the simulation can be stored. Plots of intermediate steps of the simulation or of contours of separate pieces permit feed-back to the operating theatre.

Computer Simulation↗

PubMed1995

Creating lip seal by maxillo-facial osteotomies. A retrospective cephalometric study.

Lateral head films taken immediately pre-operatively and at least 6 months postoperatively were analysed in 99 selected orthognathic surgery patients to study soft and hard tissue ratios in relation to lip seal creation. The patients were grouped according to the osseous correction carried out. In maxillary advancement patients, the overall position of stomion superius was difficult to predict when important horizontal and vertical movements had been made. The vertical movement of stomion superius was 30% of that seen at the anterior palate point, and 25% of that at the upper incisal point, when the main vector of maxillary repositioning was vertical (either intrusion or extrusion). There was a weak linear correlation between mandibular advancement at pogonion and vertical changes at stomion inferius. The correlation increased if vertical movement at menton and mentolabial angle were added as independent variables. Good linear correlations between vertical changes at stomion inferius and vertical changes at lower incisal point and menton were observed in mandibular set-back surgery. In mandibular autorotation, the best linear correlation with single predictors was found between vertical changes at stomion inferius and those at menton (about 80% + 1 mm upward movement), and vertical changes at stomion inferius and horizontal changes at lower incisal point. Vertical changes at stomion inferius were mainly determined by vertical changes at menton in genioplasties, the change at stomion inferius being 40% of that at menton. The horizontal component at pogonion had almost no influence. In combined genioplasty and Le Fort I procedures, the vertical changes at stomion inferius were 50% of those at menton + 1 mm upward movement, this difference being due to mandibular autorotation.

Adult↗

PubMed1995

Temporomandibular joint symptoms in an orthognathic surgery population.

The records of 317 consecutive patients who underwent orthognathic surgery in the Division of Maxillo-Facial Surgery of the General Hospital St. John, Bruges, Belgium, between 1.10.90 and 1.10.92 were evaluated for pre- and postoperative temporomandibular joint (TMJ) symptoms. Only 143 patients, with a normal/low angle mandibular deficiency deformity, treated by mandibular advancement, and 53 high angle absolute mandibular retrognathism patients having bimaxillary operations, were selected. Fewer TMJ symptoms were found postoperatively, than preoperatively in the total group (17.8% vs 26.5% p = 0.025, Mc Nemar). In the normal/low angle group, there was a decrease in TMJ symptoms after surgery from 30.0% to 14.6% (p = 0.0001, Mc Nemar). In the high angle group, however, more TMJ symptoms are seen postoperatively 26.4% versus 16.8% (p = 0.228, Mc Nemar). Possible hypothetical explanations are given.

Adolescent↗

PubMed1995

The 'sandwich' zygomatic osteotomy: technique, indications and clinical results.

The classical approach to lateral midface hypoplasia is reconstruction with onlays. Dislocation and asymmetry, early and late infection, and extrusion are possible complications with alloplastic implant materials. Unpredictable resorption, irregular contours and asymmetry are problems that can arise with autogenous, homogenous and hetergenous onlay grafts. We describe a technique by which the zygomatic body is luxated laterally and ventrally after a combined oblique-horizontal and vertical osteotomy. The resultant greenstick fracture at the temporo-zygomatic suture together with minimal lateral degloving causes the malar body to return to its former position. An interpositional porous hydroxyapatite block acts as a space maintainer until the osteotomy sites are ossified. The restoration of contour is performed by the zygomatic body itself, not by the implants. The indications are discussed and the results of three year follow-up are illustrated.

Adolescent↗