Gustatory dysfunction in relation to circumvallate papilla's taste buds structure upon unilateral maxillary molar extraction in Wistar rats: an in vivo study

Abstract

Background: The interaction between taste sensation and dentoalveolar innervation is still under research. teeth loss can alter taste thresholds in humans, but the underlying mechanisms are still obscure. This study investigated the effect of unilateral maxillary molars extraction on the structure of circumvallate papilla in rats. Methods: Thirty-two male Wister rats, aged 3-4 months were randomly distributed into four groups (one control and 3 experimental ) each including 8 animals. The rats were euthanized 3, 6 or 9 weeks following the procedure. The changes in trough length and the taste buds structure and number of both sides of CVP were investigated using routine histological examination followed by statistical analysis. Results: the trough toward the extraction side was obviously shorter with a noticeable decrease of taste buds' number than the non-extraction side. Taste buds were reduced in size and most of them showed signs of degeneration which was more evident in group II followed by group III, less deformity detected in group IV in comparison to the preceding 2 experimental groups. the non-extraction side of all experimental groups showed normal trough length and generally normal histology of taste buds. Conclusions: Maxillary molars extraction has a degenerative effect on the structure of taste buds and gustatory epithelium which were more marked at the extraction side and showed improvement upon elongation of follow up period.

Keywords: Molars extraction; circumvallate papilla; taste buds; taste sensation.

Figure 1.. Photomicrograph demonstrating the method of taste buds counting.

Figure 2.. Photomicrograph showing method of trough length measurement.

The trough opening was determined by a solid line drawn between the 2 troughs, the trough depth was marked by two lines, from top to bottom.

Figure 3.

( A) Photomicrograph of control group (І) showing normal circumvallate papilla surrounded by a deep narrow trough of nearly equal length on both sides and gustatory epithelium with normal taste buds (H&E, orig. Mag.X100). ( B) Higher magnification showing mature barrel shaped taste buds with taste pores, different taste cells types with prominent nuclei including supporting cells, gustatory receptor cells and basal cells (H&E, orig. Mag.X1000). H&E - haematoxylin and eosin, Mag - magnification.

Figure 4.

( A) Photomicrograph of group (ІI) showing deformity of the papilla general outline with shorter troughs toward the extraction side with fewer taste buds, and normal trough length toward the non-extraction side containing increased taste buds number (H&E, orig. Mag.X100). ( B) Higher magnification showing immature taste buds toward the extraction side arranged at different levels and decreased in size with signs of degeneration (H&E, orig. Mag.X1000). H&E - haematoxylin and eosin, Mag - magnification.

Figure 5.

( A) Photomicrograph of group (ІII) showing shorter trough length toward the extraction side with decreased number of taste buds, focal area of inflammatory cells infiltration beneath the shorter trough and normal taste buds number in the other trough (H&E, orig. Mag.X100). ( B) Higher magnification showing extraction side with decreased taste bud number with darkly stained nuclei (H&E, orig. Mag.X1000). H&E - haematoxylin and eosin, Mag - magnification.

Figure 6.

( A) Photomicrograph of group (ІV) showing trough toward the extraction side was nearly the same length as the other side, with increased number of taste buds in comparison to previous experimental groups (H&E, orig. Mag.X100). ( B): Higher magnification of extraction side showing small size-buds with a few darkly stained nuclei (H&E, orig. Mag.X1000). H&E - haematoxylin and eosin, Mag - magnification.

Figure 7.

Taste buds of the non-extraction side in all experimental groups ( A) group (II), ( B) group (III) and ( C) group (IV) showing generally normal histology except for slight enlargement (in groups II & III) and a few darkly stained nuclei (H&E, orig. Mag.X1000). H&E - haematoxylin and eosin, Mag - magnification.

Figure 8.. Bar chart showing mean number of taste buds for both sides of troughs in different groups.

(blue columns for the extraction side and green columns for non-extraction side).

Figure 9.. Bar chart showing mean trough length (µm) in the both sides in different groups.

(blue columns for the extraction side and green columns for non-extraction side).