Combined UV and IR laser ablation of dentine

Tissue ablation-rate measurements with a long-pulsed, fibre-deliverable 308�nm excimer laser

This ablation rate study has been carried out with a fibre-deliverable, 308 nm, XeCl laser, producing long pulses of 200 ns as opposed to the usual 10-20 ns. This in-depth study aimed to evaluate the ablation rates for this longer pulse length. The effects on the ablation depth of dentine, enamel, soft tissue and bone were investigated ex vivo. Radiant exposure, number of pulses, pulse repetition rate and spot size were independently varied. For all tissues, ablation depth per pulse was found to increase, initially, linearly with radiant exposure. For both dentine and soft tissue a saturation radiant exposure was determined; thereafter the ablation rate decreased. The depth per pulse increased linearly with repetition rate but decreased logarithmically with both number of pulses and spot size. The ablation depth due to a 200 ns pulse is comparable to that caused by a 10-20 ns pulse but has the advantage of fibre delivery.

Interstitial laser coagulation in benign prostatic hyperplasia: A critical evaluation after 2 years of follow-Up

Since 1993 we have prospectively followed a cumulative cohort of males with benign prostatic hyperplasia and symptomatic bladder outlet obstruction who underwent interstitial laser coagulation (ILC) of the prostate. We evaluated the safety and efficacy of ILC with respect to relief of symptoms and bladder outlet obstruction. In addition to the critical evaluation of our clinical results, the perineal and transurethral approaches were investigated as they may make a substantial impact on the overall success rate, including prostate size, number of sticks per prostate volume and type of application. A total of 59 patients were treated with the Nd-YAG laser (mediLas fibertom) between April 1993 and December 1996. At the time of reevaluation, 47 patients had completed a follow-up of up to 24 months. A perineal approach was used in 34%, transurethral in 23%, and a combined approach in 43% of the patients, depending on the preoperative volume of the prostate. 75% were high-risk patients in accordance with the ASA score (ASA III). The efficacy of treatment was assessed 6, 12, 24 and 52 weeks postoperatively in accordance with the International Prostate Symptom Score (IPS/quality of life), cystomanometric studies, peak urinary flow rate, residual volume and volume reduction of the prostate. Reduction of prostatic volume and sticks used per prostate volume were correlated to the overall success rate. A significant improvement in all voiding parameters (flow rate, residual volume), including the symptom score, was observed. P(det) decreased from an average of 90 cm H(2)O preoperatively to 42 cm H(2)O postoperatively after 24 weeks and the mean reduction in prostate volume was 14 cm(3). Interestingly, it was noted that the overall success rate was not size-related. A distinct positive correlation was found in the number of sticks performed and the improvement in objective and subjective parameters. In view of the low morbidity outcome, especially in high-risk patients, we proclaim Nd-YAG interstitial laser coagulation of the prostate to be an effective and safe alternative method of treatment for symptomatic benign prostatic hyperplasia.