[An epidemiologic survey of caries frequency and periodontal status in children 6 to 15 years of age in 11 provincial regions in central France, Bourgogne and the Ile de France]. / Enquête épidémiologique sur la fréquence carieuse et l'état parodontal chez les enfants âgés de 6 à 15 ans dans 11 départements français des régions Centre, Bourgogne et Ile de France.

An epidemiological survey of dental caries and periodontal conditions was conducted on 2,022 children in eleven french "departments" of Center of France and part of Bourgogne and lle de France. It showed a dft of 3.03 and dfs of 4.83 at the age of 6 years, as well as an increasing DMFT from 0.65 at the age of 6 to 7.26 at the age of 15. The DMFS increased from 0.91 at 6 years to 12.31 at the age of 15. The calculus index increased steadily from 0.14 at the age of 6 to 0.64 at the age of 15. The gingival index increased from 0.27 in the 6 year old, to 0.55 in the 15 year old.

[Proposal of a new analgesia test based on the observation of nociceptive behavior induced by electric stimulation of dental pulp in the rat]. / Proposition d'un nouveau test algésimétrique fondé sur l'observation des comportements nociceptifs induits par la stimulation électrique de la pulpe dentaire chez le rat.

Dental pulp was electrically stimulated in the awake rat. When the stimulus intensity was progressively increased the following four nociceptive reactions successively appeared: jaw opening reflex, scratching, head rotation, vocalization. The threshold of these four reactions was observed before and after administration of three antalgic drugs. No action of the three drugs was observed for the jaw opening reflex. However each drug showed different actions on the other three reactions.

Is electrical stimulation of the rat incisor an appropriate experimental nociceptive stimulus?

The purpose of this study was to determine whether or not tooth pulp stimulation in the rat can selectively activate the pulp nerve fibers without excitation of the periodontium and to decide if the nerve fibers situated in the pulp of the rat's incisor are involved in the nociceptive reactions caused by an intrapulpal stimulation. The experiments were carried out on 20 awake and freely moving Sprague-Dawley rats. Bipolar stimulating electrodes were inserted into the pulp of the left lower incisor and in the right incisor after removal of the pulp. Special cares were taken to avoid, on the right side, direct stimulation of the stump of the apical nerve. The jaw opening reflexes were recorded from the digastric muscles ipsilaterally to the stimulated teeth and the thresholds were compared. Using the same animals, four typical and reproducible nociceptive behavioral reactions caused by a long tooth pulp stimulation were also observed (shock of 0.5 ms at 50 Hz during 1 s). The stimulus intensity was progressively increased, and the threshold of each reaction was recorded. For each of the 20 rats tested, the jaw opening reflex and the nociceptive reactions did not disappear after removal of the pulp, but the threshold of the responses to the stimulation of the nonvital tooth were significantly above the threshold of the responses to the stimulation of the vital incisor. The conclusion was tooth pulp stimulation activates the periodontal nerve fibers in the rat, and stimulation of the incisor pulp is significant in pain study in the rat because the thresholds of the jaw opening reflex and the nociceptive reactions were increased after the tooth pulp tissue was removed.

Effects, in the rat, of various stressing procedures on the jaw-opening reflex induced by tooth-pulp stimulation.

Jaw-opening reflex (JOR) induced by a repetitive tooth-pulp stimulation delivered at 1 Hz was observed in awake, freely-moving rats. Modifications of the reflex responses of the digastric muscle were produced by foot-shock stimulation, by an oesophageal administration of placebo and a subcutaneous injection of saline. Subcutaneous injection of saline evoked a total disappearance of the reflex which returned within 30 s. Foot shock delivered for 10 s and repeated twice a minute for 30 min of intensity, just below the vocalization threshold, evoked a marked decrease of the reflex to 60 +/- 6 per cent of the control value (n = 10). Administration of arabic gum by oesophageal tube gave either: the same transient disappearance as for the subcutaneous injection in 6 rats; a progressive 28 min +/- 11 (n = 6) return to the initial value; a progressive return to a subcontrol value of 52 +/- 4 per cent (n = 7). The application of two successive stimuli resulted in a more pronounced JOR decrease. The response to electrical foot shock can be explained by a central analgesia induced by stress.

Variations of the jaw opening reflex observed in awake, freely moving rats.

Long term variations of the jaw opening reflex (J.O.R.) induced by tooth pulp stimulation (T.P.S.) have been investigated in the awake, freely moving rat. This study was specially centered on variations which could occur during the utilization of the J.O.R. as a test for analgesic drugs. Bipolar electrodes were implanted in the inferior incisor tooth pulp for stimulation and in digastric muscle for recording. J.O.R. recordings were subsequently integrated. Long term variations of J.O.R. were then observed during uninterrupted T.P.S. (1 Hz) alone or during subcutaneous (s.c.) injection, gavage or foot shock in addition to T.P.S.: --8 out of a total of 24 rats, observed during long uninterrupted T.P.S., showed a decrease of the J.O.R. The mean of reflex values, 15 min later, was 74 +/- 6% (n = 8) of the prestimulation level; --s.c. injection of saline, light handling, experimentator's brisk irruption, or sudden noise evoked a total disappearance of the reflex which completely returned within 30 sec; --gavage of arabic gum syrup gave either: . the same transient disappearance as for the s.c. injection in 6 rats; . a progressive, 28 min +/- 11 (n = 6), return to the initial value; . a progressive return to a subcontrol value of 52 +/- 4% (n = 7); --a 30 min foot shock delivered for 10 sec twice a minute at the infra-vocalization threshold evoked a marked decrease of the reflex reaching to 68 +/- 6% (n = 10) of the control (prestimulation level).