Risto Lehtinen

The analgesic action of dexmedetomidine — a novel α2-adrenoceptor agonist — in healthy volunteers

&NA; The analgesic efficacy of dexmedetomidine (DEX) — a novel &agr;2‐adrenoceptor agonist — was studied in man. Single intravenous doses of fentanyl (FEN; 2 &mgr;g/kg), DEX (0.25, 0.50 and 1.0&mgr;g/kg) and placebo were administered to 5 healthy male volunteers in a double‐blind, crossover study in randomized order. The analgesic effect of the different treatments was measured by determining the time course of pain threshold with dental dolorimetry and by quantitating subjective pain induced by a standard ischemic pain stimulus on the upper arm using a visual analogue scale (VAS). The drugs were generally well tolerated. FEN and DEX both had analgesic effects on ischemic pain, which was seen as a statistically significant decrease in subjective VAS ratings. FEN appeared to be more effective than DEX; the difference was not, however, statistically significant. Neither of the drugs affected the pain threshold measurements.

An orthopantomography study of prevalence of impacted teeth

Abstract Orthopantomograms of a total of 4,063 individuals were included in the study and were taken from patients of the Institute of Dentistry, University of Turku. Impacted teeth were found in 14.1% of the patients. The teeth most frequently impacted were the third molars, 76.1%, and of these, no difference between the maxilla and mandible was observed. No difference in sex in the prevalence of third molars was observed. The prevalence of impacted maxillary cuspids was higher in females than in males. When the prevalence of the third molars in different age-groups was studied, a decrease was found with an increase in age. The prevalence of impacted cuspids was approximately the same in different age-groups.

The mylohyoid nerve and mandibular anesthesia

Voluntary dental students received 1 injection of 1,8 ml 3% Prilocain-fenylpressin. The injection was directed beneath the mylohyoid muscle immediately behind the distal root of the first molar in order to achieve anesthesia of the mylohyoid nerve. A partial anesthesia was achieved in 21% of the subjects. In those cases, the mylohyoid nerve is, in addition to its motor innervation, also sensory to first mandibular molar.

Penetration of 27- and 30-gauge dental needles

Two types of disposable injection needles were tested clinically for pain of insertion, and penetration resistance. The 30-gauge needle required significantly less force (69 mN) than the 27-gauge needle (139 mN). The difference in pain perception was less remarkable. The author advises that a 30-gauge needle be used in any infiltration injection.

An open clinical trial of a new mouth-PUVA variant in the treatment of oral lichenoid lesions

OBJECTIVE To investigate the feasibility of topical psoralen PUVA (sensitization in photosensitizing psoralen drug + UVA radiation) treatment of oral lichenoid lesions (OLL). STUDY DESIGN A total of 16 patients with OLL were treated using a 0.01% trioxsalen ointment and UVA doses in the 0.09 to 1.80 J/cm2 range. The average number of sessions was 8.7 and a mean cumulative irradiation dose was 4.25 J/cm2. RESULTS A marked-to-complete healing occurred in 3 to 16 (19%) patients immediately after therapy, in 4 of 14 (29%) after 3 months, and in 5 of 14 (38%) after 14 months, respectively. Of the 16 subjects with OLL, five were diagnosed as oral lichen planus (OLP) and 11 were classified as oral lichenoid reaction (OLR). Post-PUVA amelioration rate in patients with genuine OLP (4 of 5, 80%) was superior to that in patients with OLR (1 of 9, 11%). CONCLUSION Topical trioxsalen photosensitization can be used in mouth-PUVA treatment, and lichen planus is a main indication for this therapy.

Bone response to hydroxyapatite particles of different shapes in rabbit tibia

Four holes drilled in rabbit tibia were filled with different commercial hydroxyapatite products. All particles caused a mild inflammatory reaction, which disappeared in 2 months. The line between the new and original bone was visible even after 6 months. No differences in healing pattern were discovered for the various products. When bone cavities are filled with hydroxyapatite particles, the shape of the particles does not seem to affect the healing process.

Rocking and twisting moments in extraction of teeth in the upper jaw

The purpose of this study was to investigate with the strain gauge method the rocking moments needed during the extraction of upper jaw teeth. In addition to the buccal and palatinal rocking moments, the twisting moment was also measured. The highest mean value of both the average and highest buccal and palatinal movements was measured during the extraction of canines. The mean value of the average buccal moments for the first and second molars was significantly higher than for premolars, but the mean value of the average palatinal moments was significantly lower for the first and second molars than for incisors and almost significantly lower than for premolars. The longest extraction times were used during the extraction of molars and canines. There was no difference in the magnitude of the moments for the upper and lower jaw canines. The extraction of the upper jaw incisors required significantly more rocking moment than the extraction of the lower jaw incisors. There was no difference between the upper and lower jaws in the mean values of the total rocking moments for premolars. The mean values of the total and highest rocking moments for molars in the lower jaw were significantly higher than the corresponding values in the upper jaw. The difference was due to the different bone structures of the upper and lower jaw and to different roots of molars in the upper and lower jaw. The extraction times for the canines and molars were significantly higher in the upper jaw than in the lower jaw.

Aspiration in local anesthesia Comparison between disposable self-aspirating and usual syringes

The positive aspirations obtained with a self-aspirating syringe (Astra, Sweden) were compared with those obtained when aspiration was performed manually (Uniject syringe, Hoechst, West Germany). The subjects were 1186 army recruits, to whom 2348 injections of local anesthetic were given in connection with dental treatment. When aspiration was performed manually, the results were positive in 4.7% of the cases; with the self-aspirating syringe, they were positive in 1.1% of the cases. The total frequency of positive aspirations was significantly higher (P less than 0.001) with the manual aspiration technique than with the self-aspirating syringe was due to the fact that the value did not include aspiration occurring when the injection needle ruptured small blood vessels.

Penetration of disposable needles

Six types of disposable injection needles were tested clinically for the intensity of pain caused, and their penetration capacity measured. The force nedded differed greatly with different needle types (120-250 mN). The design of the needle point was observed to have the greatest effect on the pentration capacity and the intensity of pain. To penetrate the tissue well, the needle point should have secondary bevels at the tip of the bevelled surface. The majority of the needles fulfilled this requirement.

Aspiration using prefilled dental anesthetic cartridges

The purpose of this study was to make clear if aspiration was possible by the non-aspirating technique using non-aspirating cartridges. Four prefilled anesthetic cartridges used in Scandinavia generally were selected for study. The pressure required for aspiration varied between 130--320 mm Hg. In the majority of cases, aspiration did not occur in the pressure of 320 mm Hg. Thus, if the patient has normal blood pressure- the aspiration occurs very seldom by using non-aspirating cartridges.