Modified technique for the exposure of the inferior alveolar nerve in rats.

The inferior alveolar nerve (IAN), a branch of the mandibular division of the trigeminal nerve, is a major component of the neurovascular bundle along with the inferior alveolar artery and vein. In rats, when exposed using an external oral approach while remaining intact, it can serve as an important tool to study the different effects of neuromediators and assess the role of different groups of nerve fibers. This paper describes a new technique to expose this nerve giving some experimental results to support its usefulness.

Comparison of CT scanograms and cephalometric radiographs in craniofacial imaging.

OBJECTIVE: To compare measurements from human skulls and their images from cephalometric radiographs (CR) and computed tomography (CT) scanograms, in order to gauge the potential clinical use of the latter. DESIGN: Based on specific inclusion criteria, including stable centric occlusion, 13 adult skulls were selected from a larger collection. The mandible was taped to the maxilla after securing the occlusion of teeth and condylar seating in the glenoid fossa. Lateral and posteroanterior cephalographs and CT 'scout views' were taken of each skull by standardized methods. Landmarks were identified on skulls and images. OUTCOME MEASURES: Linear measurements were made on all three records; angular measurements only on CR and CT images. Intraclass correlation coefficients (r) were calculated to assess similarity among records. Paired t-tests were used to compare differences between mean measurements. RESULTS: No statistically significant differences were noted between mean angular values on CR and CT views (P > 0.05). The highest correlations were observed for several vertical midline distances between CT and direct skull measures: 0.82 < r < 0.995-greatest for nasion-menton. For sagittal distances, the highest correlation was between the direct measure of condylion-pogonion and its CR image (r= 0.73). Correlations between CR and skull transverse measures were higher (0.46 < r < 0.80) than the corresponding skull vs. CT measures (0.06 < r < 0.38). CT and CR images are 2D slices and projections, respectively, of 3D structures. Vertical CT and skull measures correspond because the CT projection reflects a 1:1 ratio in the midsagittal plane; CT projected lateral images are smaller than the skull measures. The CR image reflects a distortion (approximately 8%) that brings Co-Pg closer to its anatomic distance, inadvertently contributing to better clinical planning, particularly in orthognathic surgery. The pattern of distortion of PA images was in opposite directions for CR and CT views. CONCLUSIONS: Cephalograms and CT scanograms are close in depicting angular relations of structures, but they differ in the accuracy of imaging linear measurements, because the location and size of an object within the imaged 3D structure varies with both records. Logistic and economic considerations favor the use of cephalographs.

Gagging prevention using nitrous oxide or table salt: a comparative pilot study.

PURPOSE: The objective of this study was to compare two methods for reducing gagging induced by stimulation of the soft palate: table salt and nitrous oxide inhalation sedation. MATERIALS AND METHODS: Fifteen healthy volunteers, eight men and seven women with a mean age of 20.6 years, were subjected to a gagging event three times using a large tablespoon to stimulate the soft palate: event 1 = spoon alone, event 2 = spoon and table salt on the tip of the tongue with a 30-minute break between events 1 and 2, and event 3 = spoon and nitrous oxide sedation on another day. Time in seconds was measured from the moment the spoon touched the soft palate until gagging was felt using a chronometer held by the subject. RESULTS: The mean time for eliciting the gagging reaction was 7.7 seconds for the spoon alone, 8.9 seconds for the spoon and table salt, and 24.0 seconds for the nitrous oxide sedation. Nitrous oxide inhalation sedation significantly (P < .001) reduced the gagging/retching reaction, whereas there was no significant time difference in gagging reaction between stimulation with the spoon alone or when table salt was added. CONCLUSION: Within the limits of this study, table salt did not seem to reduce the time to triggering the gag reflex, whereas nitrous oxide had a substantial effect.

A perfusion technique for the determination of pro-inflammatory mediators induced by intradental application of irritants.

INTRODUCTION: Several morphological and functional features contribute to the consideration of the tooth as a separate compartment having special type of innervation and special immune mechanisms. This study describes a new method allowing the intradental perfusion of rat incisors for the in vivo assessment of pulpal reaction to inflammatory agents. METHODS: Under deep anesthesia, the distal 2-3 mm of each of the rat lower incisors was cut and wrapped in a polyethylene tubing connected to a perfusion chamber made of tigone tubing (ID 1/8 in., volume 100-150 microl). Several groups of rats (n=5 each) were used for intradental application of either saline, capsaicin (100 microg in 100 microl), or endotoxin (ET, 20 microg in 100 microl) for a period of 40 min followed by filling the tooth chamber with saline and collecting the perfusate every 40 min for a period of 8 h. The collected perfusates were stored at -70 degrees C for subsequent determination of the concentration of prostaglandin E(2) (PGE(2)) and nerve growth factor (NGF) by enzyme-linked immunosorbent assay (ELISA). RESULTS: Dentinal injury produced a moderate increase in the levels of NGF and PGE(2) in incisors perfused with saline. Application of ET or capsaicin, however, produced a highly significant increase in the levels of both mediators. These effects peaked at 1.5-3 h for PGE(2) and at 5 h for NGF. Capsaicin showed the most significant effects. DISCUSSION: The reported results cannot be attributed to any factor other than the inflammation of the incisor's pulp, because the described chamber does not allow any spread or leak of the applied irritants. Further studies using other reagents can allow the determination of the variation of the levels of the various pro-inflammatory mediators and their modulation by treatment with anti-inflammatory drugs.