Hard tissue cutting and drilling with lasers

Hard tissue cutting and drilling with lasers

029C Maxillofacial pathology/oncology/wound repair~miscellaneous O 2 9 C - Maxillofacial pathology/oncology/ wound repair/miscellaneous 1. Three-Di...

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Maxillofacial pathology/oncology/wound repair~miscellaneous

O 2 9 C - Maxillofacial pathology/oncology/ wound repair/miscellaneous

1. Three-Dimensional Surgical Planning in Virtual Reality Environment


within alveolar region or upper portion of the canal; no recurrent tumor was observed. In 5 of 10 patients with recurrent tumor, both pattern and depth of the bone resorption showed the moth-eaten type with 1 alveolar region, 2 upper portions of the canal and 2 involving the canal. Ten-year survival rate was 62.6% for marginal and 52.4% for hemior segmental mandibulectomies.

Xia, J., Wang, D., Yeung, R., Samman, N., Tideman, H. Oral and Maxillofacial Surgery, Faculty of Dentistry, Prince Philip Dental Hospital, University of Hong Kong A computer system "three-dimensional virtual reality surgical planning and simulation for orthognathic surgery" is designed, programmed and established. This system combines virtual osteotomy, surgical planning, simulation and prediction in three dimensions and immersive virtual reality environment on conventional personal computer. This system is also an immersive virtual reality workbench for orthognathic surgery. The object is the human skull, the most complicated structure of the whole body. The surgeon immerses in the virtual realitY environment with stereo glasses, holds a virtual "scalpel" (3D Mouse), to operate a "real" patient (visualization). The operator's clinical experience is crucial. To simulate the correct virtual surgical procedures, the real clinical experience must be credible. A patient example is presented to demonstrate the clinical application of this methodology.

2. Evaluation of Comparative Results Between Marginal and Hemi- or Segmental Mandibulectomies for Squamous Cell Carcinoma of the Lower Gum

Ohya, T., Kudo, K. First Department of Oral and Maxillofacial Surgery, School of Dentistry, Iwate Medical University, Morioka, Japan It is important to achieve a continuous and marginal mandibulectomy in order to maintain the postoperative maxillofacial morphology and function in squamous cell carcinoma of lower gum. Results after marginal and hemi- or segmental mandibulectomies were compared.

Subjects and methods Thirty-six patients with pathological diagnosis from 1975 to 1994 consisted of 17 with hemi- or segmental mandibulectomy and 19 with a marginal one. Results were discussed as to 2 patterns and 3 depths of the radiological bone resorption, recurrent tumor and survival rate.

Conclusion Modified marginal mandibulectomy, which removes a mandibular canal and maintains/or reconstructs a mandibular rim, should be used instead of segmental one, if the tumor remains within upper portion of the mandibular canal.

3. Early Experience of Digitized 3-D Photosteophotographic Imaging

Booth, R, Surwald, C Queen Victoria Hospital, East Grinstead, West Sussex, England A digitized 3-dimensional image of the face has many valuable uses. These include accurate measurements of facial growth, measurements of facial swelling. Also the ability to manipulate images to predict surgical procedures. These images can also be integrated with CT scans. In the past such images were only possible using CT scans. More recently Linney a created such images by rotating the patient and scanning projected laser lines. The former method requires ionizing radiation and the latter requires cumbersome immobile equipment. The system to be presented the VISAGE 2 system instantaneously captures a 3-D digitized image using high resolution cameras. The system is mobile, simple to operate, and has an accuracy of less then 0.14 mm. It creates the image from approximately 20,000 points. In this presentation the principles of image capture are demonstrated and the potential uses discussed.

References 1. MCCANCE AM, NOss JP, LINNEY AD, JAMES DE. Three Dimensional analysis techniques. Cleft Palate Craniofacial Journal 1997: 34(1): 36 45. 2. VISAGE, TRICOgDER TECHNOLOGY VLC, UNIT 6 LONG ROOM, HAgEFIELD UB9 6JA, UK.

4. Hard Tissue Cutting and Drilling with Lasers

Eyrich, G), Sailer, H, 1, Nubler-Moritz, M. 1, Bruder, E.2 Results No recurrent tumors occurred in 13 of 17 patients with hemi- or segmental mandibulectomy. In 4 patients with recurrent tumors, both pattern and depth of bone resorption were of pressure or moth-eaten type and depth of alveolar region or upper portion of the mandibular canal. In 9 of 19 patients with marginal mandibulectomy, pattern and depth of the bone resorption had all pressure types and depths

1Department of Cranio-Maxillofacial Surgery, 2Department of Pathology, University of Zurich, Zurich, Switzerland Hard tissue drilling and cutting with lasers was one of the most prestigious challenges for many physicists and clinicians over the last decade. The use of ErbiumYAG lasers


029C- Maxillofacial pathology/oncology/wound repair~miscellaneous

promised good results while CO2 lasers, limited by physical parameters, showed dissatisfying results. New technical modifications of wave length, pulse modus, pulse duration, scanning parameters, and the use of cooling systems revealed excellent results. Two different C02 laser systems were used for hard tissue cutting and drilling compared to conventional laser systems. A series of in vitro and in vivo examinations in patients was performed. Histology from osteotomy sites and from cavities and pulps of vital teeth showed minimal carbonization (x<4 g), absence of hard tissue necrosis; and inflammatory reaction of the pulp. In vitro temperature measurements presented minimal temperature rise ( x < l - 3 ~ Cutting of 1 mm dentine in 7 sec was accomplished. Hard tissue drilling and cutting with CO2 lasers is a promising technique that is tissue preserving, efficient and precise.

5, Surgical Uprighting of Impacted Lower Second Molars: Clinical and Radiographic Evaluation

Kittidumkerng, W.

Department of Oral and Maxillofacial Surgery, PSU, Songkla, Thailand The impacted lower second molar is a rare condition. It may become a problem during or after orthodontic treatment. There are several methods recommended for correction of such a condition, but the surgical uprighting seems to be the most useful technique with predictable results. This purpose o f this study is to clinically and radiographically evaluate the early result of the surgical uprighting of impacted lower second molars. From October 1997 to October 1998, six consecutive patients with 8 impacted lower second molars were treated via surgical uprighting only. The patients were followed up at 3month intervals up to 12 months. The orthopantomographs were obtained preoperatively, immediately postoperatively and at 3, 6 and 12 months postoperatively. Clinical evaluation looked for tooth mobility, peridontal pockets, tooth position and other clinical symptoms. Radiographic evaluation included the inclination of the impacted teeth in relation to the adjacent lower first molars, root formation, pulpal change and mesial bone regeneration. The result showed that all teeth are clinically stable and in a good position at the longest follow-up period. No periodontal pocket was detected, but two patients had overgrowth of the buccal mucosa at the occlusal line. Continuation of root formation was also seen in all cases without pulpal changers. The result of this study is similar to others' investigations. It can be concluded that the surgical uprighting of impacted lower second molars is simple with predictable results.

6. Outcome Assessment in the Surgical Management of Obstructive Sleep Apnea

Gronbach, K.

University of Michigan, Department of Oral and Maxillofacial Surgery The problem Obstructive sleep apnea is a disease with a high incidence, especially in the adult population over sixty years of age. Continuous positive airway pressure has a compliance of approximately twenty percent. Through a surgical approach patients may be brought to a level consistent with that of a cure as defined by limitations of a specific respiratory disturbance index and oxygen desaturation. Others may not satisfy the strict definition of cure, but nonetheless function with only mild or no subjective complaints and symptoms of obstructive sleep apnea. This study looks at outcome assessment in a group of patients treated with genial advancement and hyoid suspension (GAHS) and uvulopalatopharyngoplasty (UPPP). Materials and methods This is a retrospective preliminary analysis of records of patients whom have undergone GAHS and UPPP for the correction of obstructive sleep apnea. From a group of approximately twenty-two patients dating from January 1997, only eleven had records complete for evaluation. Several measurements were taken to objectively view the post-surgical changes. Results The respiratory disturbance index decreased to less than one-half the preoperative values, from 45.76 to 21.76. Minimum levels of oxygen desaturation rose from 82.82% to 87.93%. The posterior airway space increased from 1.9 mm to 3.95 mm. The hyoid to mandibular plane distance decreased from 25.9 mm to 16.55 ram. Nine of eleven patients improved after surgical treatment. Complications included one case of broken sutures and two infections necessitating removal of suspension. Conclusions Genial advancement, hyoid suspension and uvulopalatopharyngoplasty is a viable and useful method of surgical correction of obstructive sleep apnea. Outcome assessment measures the subjective as well as objective results of surgery. This current analysis is the basis for study of the entire group at our institution which have undergone GAHS and UPPR