Osteotomy with 80-?s CO2 laser pulses ? histological results

Abstract

Haemostatic and aseptic effects and intricate cut geometry are beneficial aspects of non-contact laser osteotomy. Collateral thermal damage, however, has severely limited the use of conventional lasers. The purpose of this study was to test the side effects on bone after cutting it with short CO2 laser pulses and simultaneous application of a fine air-water spray. The 10.6 microm CO2 laser emitted 80 micros pulses of 46 mJ energy, f=100 Hz, focused to a spot diameter of 130 ìm. Scan rate amounted to 40 mm/s. To approximate live conditions 10 samples of cortical bone and 10 rib segments were prepared immediately after sacrificing of pigs. A reference cut with a bandsaw and three laser cuts with an increasing number of beam passes (4, 16, 64) were performed on each sample. Half of the samples were decalcified in EDTA. The others were embedded in plastic to cut non-decalcified sections. The laser incisions were not accompanied by carbonisation. The incisions with slightly convergent walls were 150 ìm wide. The depths of the cavities increased with the number of the beam passes from approximately 0.5 mm (4 passes) to 3 mm (64 passes). At the border of the incisions two narrow zones of damage were noted: an amorphous intensively stained zone of 1-3 microm width and a wider, also sharply demarcated but faintly stained zone of 7-10 microm. A broader zone of about 50 microm was characterised by empty lacunae and osteocyte damage. These effects were not predictable; intact osteocytes were also observed near to the cut surface. Polarised light microscopy showed no alterations in the inorganic structure of the bone at the cut borders. The histological results indicated only minimal damage to bone ablated at the specified parameters. The described laser procedure might have advantages over mechanical instruments.

Influence of effective number of pulses on the morphological structure of teeth and bovine femur after femtosecond laser ablation

“…23,24 A Er: YAG laser (wavelength 2.94 μm) with a strong water absorption became popular in the past years for applications in orthopaedical, maxilofacial, and dental surgeries and for possible use in periodontal surgery. 23,25,26 Carbonizations were also observed using Nd:YAG lasers, 12,26,27 unlike what happened in our study using a femtosecond laser.…”

Er:YAG laser osteotomy for removal of impacted teeth: Clinical comparison of two techniques

“…For the impacted canines in the upper jaw, a similar procedure was used (Figs. [2][3][4][5]. In the case of the non-contact Er:YAG handpiece, special care was necessary to guide the handpiece, because there is no mechanical support between the handpiece and the bone surface.…”

“…In fact, when compared to traditional bone saw or dental bur procedures, the time required to produce comparable intrabony incisions is reasonable and the zone of thermal damage is minimal [2][3][4]. The free electron laser, for example, when tuned to wavelengths of 3.0, 6.1, or 6.45 m is strongly absorbed by protein and water and thus efficiently cuts bone with minimal evidence of a char layer [5].…”

Effects of femtosecond laser irradiation on osseous tissues

“…Carbon dioxide lasers (10.6 mm), targeting the mineral component of bone have shown some success in bone removal, but severe tissue charring can occur [11,12]. ER:YAG (2.94 mm), which has a strong water absorption, has been gaining popularity over the past few years for possible use in orthopedics, dental and maxillofacial surgery [3,13], as well as periodontal surgery applications [14].…”