Histologic study of oral mucosa wound healing: A comparison of a 6.0 to 6.8 mm pulsed laser and a carbon dioxide laser

Histologic study of oral mucosa wound healing: A comparison of a 6.0 to 6.8 mm pulsed laser and a carbon dioxide laser

1222 CURRENT LITERATURE Carbon Dioxide Laser Resurfacing: low-Up in 2,123 Patients. Weinstein 25:109, 1998 Long-Term FolC. Clin Plast Surg Carbon ...

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1222

CURRENT LITERATURE

Carbon Dioxide Laser Resurfacing: low-Up in 2,123 Patients. Weinstein 25:109, 1998

Long-Term FolC. Clin Plast Surg

Carbon dioxide (CO*) laser resurfacing has become increasingly popular as a method of facial rejuvenation, enabling the surgeon to repair sun-damaged skin, wrinkles, and acne scars precisely. Over the 5-year period of this study, improvements appear to be long lasting. To resurface skin successfully, it is best to use lasers with short absorption length, so that controlled removal of abnormal epidermis and dermis is possible. When COa lasers impact on skin, the water in the epidermal cells absorbs the laser beam and is heated to lOO”C, which leads to vaporization of the epidermal cells. The dermis responds to the conducted heat and produces a band of coagulation necrosis, the depth of which is determined by the fluence and time on the tissue. Indicators of resurfacing depth include color, pore size, and surface topography. Different CO* laser systems behave differently. COa lasers may be used to treat wrinkles, acne scars, exophytic skin lesions, post-traumatic and postoperative scars, rhinophyma, and actinic cheilitis. COa laser resurfacing is contraindicated in patients with appendageal abnormalities such as those taking oral retinoids, a history of keloids or scarring, extrafacial lesions and darker-skinned patients. Oral antiviral agents are given preoperatively and continued until re-epithelialization. No other pretreatment regimen is necessary. Anesthesia may be limited to local, regional nerve blocks, or tumescent and/or be supplemented by intravenous sedation and general anesthesia. Eye shields should be used. Occlusive dressings should be placed postoperatively. Closed dressings promote faster re-epithelialization, greatly minimize pain, eliminate patient participation in wound care, help patients to cope psychologically, and minimize contact dermatitis. Antiviral agents, antibiotics, and steroids are routinely prescribed postoperatively. Postoperative skin care after reepithelialization includes the use of a moisturizer, cleanser, and sunscreens. Complications include erethema, hyperpigmentation, acne, and milia.-R.H. HAUG Reprint bourne,

requests Victoria,

to Dr Weinstein: Australia.

174 Victoria

Parade,

East Mel-

Segmental Mandibular Reconstruction by Distraction Osteogenesis Under Skin Flaps. Oda T, Sawaki Y, Fukuta K, et al. Int J Oral Maxillofac Surg 27:9, 1998 After cancer treatment, reconstruction of the mandible, often in combination with radiotherapy and/or chemotherapy, is aesthetically and functionally important. Many methods have been advanced to accomplish this, and each has advantages and disadvantages. Distraction osteogenesis produces new bone without the need for grafting, and may be useful to bridge mandibular defects. Several studies have raised the possibility that this technique could be used for reconstruction of surgical defects after segmental cancer ablation. This study was intended to evaluate whether a skin flap used for intraoral lining would preclude reconstruction of a mandibular defect using distraction osteogenesis. A dog model was chosen because of its frequent use in previous mandibular distraction studies. In five adult dogs, molars and premolars were extracted and skin flaps from the neck were prepared for delayed transplantation. Two weeks later, a 25 mm segment of the mandible was excised with surrounding

periosteum and gingivae. The mandible was stabilized with a reconstruction plate and the intraoral defect repaired with a pedicled skin flap. A proximal transport segment was created and an external distraction device was applied. After 1 week, distraction began at a rate of 1 mm/d for an average of 25 days. As the distance between the distal and transport segments shortened, the soft tissue pedicle bulged outward. After completion, the appliances were left for 12 weeks, and the dogs were killed. Radiological and histological examinations showed new bone at the distraction sites. Previous studies have shown the necessity of removing intervening soft tissue between the transport segment and distal stump to achieve bony union. This was not done in this study, and as a result nonunion of the transport segments to the distal stumps occurred in all animals. The results, nevertheless, showed that it is feasible to bridge a mandibular defect that is covered with a skin flap using distraction osteogenesis. The skin flap would need to be trimmed as distraction progresses, and eventually removed to avoid nonunion.ROGER

E. ALEXANDER

Reprint requests to Dr Oda: Department of Oral Surgery, University School of Medicine, 65 Tsuruma-cho, Showa-ku, 466, Japan

Nagoya Nagoya

Histologic Study of Oral Mucosa Wound Healing: A Comparison of a 6.0 to 6.8 mm Pulsed Laser and a Carbon Dioxide Laser. Bryant GL, Davidson JM, Ossoff RH, et al. Laryngoscope 108:13,1998 The carbon dioxide (C02) laser is a commonly used laser for tissue ablation and incision for surgery in the head and neck. Its use is not without complications attributable to thermal energy penetrating unintended tissues. This study is a histological examination of wound healing in the canine model comparing wound healing from a scalpel, a continuous COa laser and a pulsed Vanderbilt free electron laser. Eight mongrel dogs had a 2.5 cm wound created in the buccal mucosa to a depth of 1 mm. Two dogs were killed at time 0, 3 days, 7 days, and 14 days. Each wound was compared histologically and scored based on collagen deposition. Findings were that a significant delay in wound healing was observed when incisions were made with the CO2 laser in continuous mode. When using the short-pulsed, free electron laser a smaller delay was found compared with the scalpel wound healing. Conclusions drawn by the authors were that continuous mode COa lasers can cause excess thermal damage to tissue that impairs wound healing and that a pulsed mode laser improves wound healing as compared with scalpel wounds.-J. BROKLOFF. Reprint requests to Dr Reinisch: Department Vanderbilt University Medical Center, Nashville,

of Otolaryngology, TN 37232.

Experimental Study on the Tooth Bud in Area of Distraction Osteogenesis. Sawaki Y, Hagino H, Oda T, et al, J Jpn Stomatol Sot 47:39, 1998 The effects of distraction osteogenesis of the mandible on the tooth germ were studied in five healthy male mongrel dogs of approximately 3 months of age with deciduous dentition. After the location and the degree of root formation of the permanent mandibular first molar were confirmed by radiographs, the lower border of the mandible was exposed via a submandibular approach and a corticotomy was performed all around the area with care not to