Short-term tissue response to potential root-end filling materials in infected root canals.

The short-term tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol), were compared with that to amalgam using a previously devised experimental model. In 24 premolar teeth of beagle dogs (47 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periradicular lesions. On each root, an apicoectomy was performed and root-end cavities prepared to receive fillings of each material. The teeth and surrounding jaw were removed after 2 weeks (23 roots) and 1 week (24 roots); they were then prepared for histological examination. The tissue response to amalgam fillings after 2 weeks and 1 week was marked by moderate or severe inflammation on all roots, and extended to < or = 0.5 mm or > 0.5 mm in 15 out of 16 roots. In contrast, after 2 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation, while the tissue response to Vitrebond was the best of the three materials, and was also the least extensive. After 1 week, the overall best tissue response was with Vitrebond, followed by Kalzinol. The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were not statistically significant (P < 0.02). However, the differences between materials for both time periods with no inflammation or inflammation extending < 0.2 mm when compared with that with inflammation extending > 0.2 mm (< or = 0.5 mm or > 0.5 mm) were statistically significant (P < 0.01). Apart from amalgam, in which healing was marked by the persistence of a localized focus of inflammation adjacent to the root-end filling, even though there were intersample variations, there was little overall difference in the temporal and qualitative healing response to Vitrebond and Kalzinol. Both Vitrebond and Kalzinol have potential as root-end filling materials, as the tissue response was considerably more favourable than that to amalgam even in the short-term.

Effect of palatal injections on pulpal blood flow in premolars.

The effect of palatal infiltration injections using 2% lignocaine hydrochloride with 1:80,000 adrenaline was evaluated for sound maxillary first premolar teeth. The influence of the injections on pulpal blood flow and local anaesthesia was investigated. Ten human volunteers were given the following injections on different days: 1 ml palatal infiltration; 1 ml buccal infiltration; 1 ml palatal and 1 ml buccal infiltration; and 2 ml buccal infiltration. The blood flow was observed with a laser Doppler flowmeter with the probes held against the buccal surfaces of the teeth by a splint. Blood flow was recorded digitally on a computer in machine units. Pulpal anaesthesia was assessed using a monopolar electric pulp tester. All injections significantly reduced blood flow from baseline levels (p<0.05). The 1-ml palatal injection produced a significantly longer period of reduced blood flow (mean 40 min) compared with the other injections (p<0.05). The duration of blood flow reduction was shorter than the duration of pulpal anaesthesia for every injection. Only seven out of 10 palatal injections achieved pulpal anaesthesia. The 2-ml buccal injection and the combined buccal and palatal injections produced significantly longer anaesthesia than the 1-ml buccal injection (p<0.05).

A radiographic study of the effect of various retrograde fillings on periapical healing after replantation.

An effective retrograde sealing procedure places great demands upon both technique and materials. Prevention of micro-leakage, biocompatibility and stability of the material in the apical tissues are very important. To evaluate potential retrograde filling materials, a replantation model has been developed in which extracted permanent molars were replanted in monkeys after apicectomy of each root, preparation of a 2-mm deep retrograde cavity and its sealing with various dental materials. Prior to retro-filling the remaining pulp was exposed to saliva. Apicected molars which were infected and did not receive retrograde fillings served as positive controls. Periapical healing was evaluated radiographically after 8 weeks based on planimetric measurements of the size of the periapical radiolucency. The following dental materials were tested: amalgam, glass ionomer cement, calcium-hydroxide lining cement, AH 26 root canal sealer, various zinc oxide-eugenol cements, Cavit, and gutta-percha with various sealers. The materials which were associated with better apical healing than the infected controls were glass ionomer cement, Cavit, and the zinc oxide-eugenol cements. When plain zinc oxide-eugenol or IRM were combined with a gutta-percha core, healing was best and not statistically different from normal apices. It was concluded that radiographic assessment at 8 weeks of molar teeth retrograde filled prior to replantation could be a valuable method for discrimination of potentially useful materials in vivo.

Adrenaline in local anaesthesia: the effect of concentration on dental pulpal circulation and anaesthesia.

This study investigated the effects of inferior alveolar nerve block anaesthesia using 2% lignocaine with 1:100,000 or 1:80,000 adrenaline on pulpal blood flow in mandibular molar and canine teeth in 10 human subjects by laser Doppler flowmetry. The duration of pulpal anaesthesia in the teeth using electric pulp testing was also investigated. The injection of 2 ml of 2% lignocaine with 1:100,000 adrenaline caused a decrease in pulpal blood flow in both teeth in every subject. The mean pulpal blood flow in the canine tooth at 15 min was 58% of the baseline value whilst that in the molar was 76%. These values were not significantly different from the reduction in pulpal blood flow produced by 2% lignocaine with 1:80,000 adrenaline. Both solutions produced a reduction in blood flow that was of shorter duration than pulpal and soft tissue anaesthesia, and of shorter duration in the molar tooth compared with the canine. When 2% lignocaine with 1:100,000 adrenaline was injected, the mean reduction of blood flow was of shorter duration (canine, 60 min; molar, 42 min) than following 2% lignocaine with 1:80,000 adrenaline (canine, 93 min; molar, 72 min); these differences in reductions were statistically significant (P < 0.05). Using 2% lignocaine with 1:100,000 adrenaline, the mean duration of pulpal anaesthesia was 76 min in the canine tooth compared with 58 min in the molar tooth. Full soft tissue anaesthesia lasted for 117 min. These values were reduced significantly when compared with the lignocaine solution containing 1:80,000 adrenaline (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytotoxicity of potential retrograde root-filling materials.

The cytotoxicity of potential retrograde root-filling materials was assessed using the Millipore filter method. A light-cured glass ionomer cement, Vitrebond (VB), and three reinforced zinc oxide-eugenol cements, Kalzinol, IRM and ethoxybenzoic acid (EBA) cement, were compared with amalgam. Twenty standardized pellets of each material, 10 fresh and 10 aged by storage in sterile distilled water for 72 h were produced. Ten filters were included as controls: five filters with a cell monolayer, but without test specimens, and another five without cells but with test specimens. Fresh IRM exhibited the most pronounced cytotoxic effect and the difference was statistically significant compared with all the other materials. There was no statistically significant difference between fresh VB, Kalzinol, EBA cement and amalgam. When aged, Kalzinol was the most cytotoxic and the difference was statistically significant compared with the other materials. Aged IRM was the second most cytotoxic material and this too was statistically different. The cytotoxicity of VB, EBA, and amalgam did not differ significantly from one another.

Action of adrenaline on the effect of dental local anaesthetic solutions.

This study investigated the effects of dental local anaesthetic solutions containing either 2% plain lignocaine or 2% lignocaine with 1:80,000 adrenaline. The duration of anaesthesia and the occurrence of a reduction in blood flow together with its duration were examined in the dental pulps of maxillary central incisor teeth in 10 human subjects. The local anaesthetic solution was injected into the soft tissues adjacent to the apex of the sound maxillary incisor tooth. The blood flow in the dental pulp was assessed by a laser Doppler flowmeter, and the effectiveness of pulpal anaesthesia was determined by an electric pulp tester, both at timed intervals. The injection of 1-2 ml of 2% plain lignocaine had no significant effect on blood flow in the pulp of the incisor tooth in eight of 10 subjects. In the other two, there was a small but significant increase. The duration of pulpal anaesthesia was 25.1 min (SD 6.23). Following injection of 1 ml of 2% lignocaine with 1:80,000 adrenaline, there was a significant reduction (31%) of pulpal blood flow in every subject (p < 0.05). The duration of reduced blood flow was 68.5 min (SD 9.73). The duration of pulpal anaesthesia was 100 min (SD 15.09), four times the duration of anaesthesia induced by plain lignocaine. The anaesthetic solution with vasoconstrictor produced far longer anaesthesia more consistently at a lower dose than the plain solution.