Abrasion and dental pulp morphological changes in occlusal dysfunction

Abstract

Aim: The authors set out to assess if the presence and the degree of severity of the abrasion, as a consequence of the occlusal dysfunction, determine further morphological changes in the dental pulp.

Materials and methods: Study group included teeth dental pulp from 45 cases with occlusal dysfunction, subsequently divided into two subgroups: 24 cases with abrasion (AB) and 21 cases without abrasion (NONAB). The set of morphological parameters of dental pulp were thicknesses of the outer layer, inner layer and entire peripheral pulp zone, the presence of pulpal calcifications and their extent within the dental pulp, the presence of interstitial fibrosis and its extent within the dental pulp and the vascular density (VD) of pulpal capillary network. Tissue samples were fixed in 10% buffered formalin, embedded in paraffin, and sectioned off at 4 μm. Serial slides were stained with Hematoxylin-Eosin (HE), Masson's trichrome (MT) and anti-cluster of differentiation 34 (CD34) antibodies labeled with 3,3'-Diaminobenzidine (DAB) and transformed into virtual slides on which the above-mentioned parameters were studied comparatively with the help of a dedicated in-house software, realized in MATLAB (MathWorks, USA). The numerical values of the assessed parameters were also stratified in classes, thus obtaining score scales for each parameter. Statistical tools used were Lilliefors test, t-test (two-sample assuming equal variances), Mann-Whitney test, Pearson's correlation test, one-way analysis of variance (ANOVA) test and χ² (chi-squared) test.

Results and discussions: Both peripheral zone (PZ) and its layers individually tended to be thicker in the teeth with abrasion than in those without abrasion. Also, teeth with abrasion tended to develop larger amounts of calcium deposits in their dental pulp than teeth without abrasion. On the other hand, fibrotic tissue in dental pulp had no relationship with the presence or absence of abrasion. PZ as a whole and its layers evolved together in the same way, with a stronger correlation in the group of teeth without abrasion. Deposits of calcium evolved in the opposite direction to both the amount of fibrous tissue and the capillaries density of the dental pulp. Consequently, the amount of fibrous tissue and VD evolved together in the same way, more pronounced in the teeth without abrasion.

Conclusions: Our preliminary study pointed out that different components of the dental pulp showed slight to moderate changes depending on the degree of abrasion in teeth with occlusal dysfunction.

Figure 1

Windows of the software used: (a) Aperio ImageScope [v12.3.2.8013]; (b) analySIS Pro 5.0; (c and d) Software designed in the MATLAB (MathWorks) program

Figure 2

Teeth distribution in the two groups. AB: Abrasion; C: Canine; IC: Incisive; M: Molar; NONAB: Non-abrasion; PM: Premolar

Figure 3

Relationship abrasion–dental arches. A: Abrasion degree; MB: Mandible; MX: Maxillary

Figure 4

Relationship abrasion–sagittal plane. The outer layer of peripheral zone. A: Abrasion degree; L: Left; R: Right.

Figure 5

Comparative statistical data between the two groups of outer layers of peripheral zone thicknesses – WZ_Th. AB: Abrasion; AV: Mean value; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; STDEV: Standard deviation; WZ: Free zone of Weil

Figure 6

Comparative statistical data between the two groups of inner layers of peripheral zone thicknesses – CZ_Th. AB: Abrasion; AV: Mean value; CZ: Cellular zone; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; STDEV: Standard deviation

Figure 7

Comparative statistical data between the two groups of entire peripheral zone thicknesses – PZ_Th. AB: Abrasion; AV: Mean value; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; PZ: Peripheral zone; STDEV: Standard deviation

Figure 8

Comparative statistical data between the two groups of calcifications amounts – C. AB: Abrasion; AV: Mean value; C: Calcification; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; STDEV: Standard deviation

Figure 9

Comparative statistical data between the two groups of fibrosis amounts – F. AB: Abrasion; AV: Mean value; F: Fibrosis; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; STDEV: Standard deviation

Figure 10

Comparative statistical data between the two groups of vascular densities – VD. AB: Abrasion; AV: Mean value; MAX: Maximum; MIN: Minimum; NONAB: Non-abrasion; STDEV: Standard deviation; VD: Vascular density

Figure 11

Relationship between PZ and its layers depending on abrasion presence: (a and b) WZ–CZ; (c and d) WZ–PZ; (e and f) CZ–PZ; (a, c and e) Abrasion group; (b, d and f) Non-abrasion group. CZ: Cellular zone; PZ: Peripheral zone; WZ: Free zone of Weil.

Figure 12

Relationship between fibrosis, calcifications and VD depending on abrasion presence: (a and b) Fibrosis–calcifications; (c and d) Fibrosis–VD; (c and f) Calcifications–VD; (a, c and e) Abrasion group; (b, d and f) Non-abrasion group. VD: Vascular density

Figure 13

Relationship between pulpal changes and abrasion degree: (a) Abrasion–WZ thickness; (b) Abrasion–calcification amount; (c) Abrasion–CZ thickness; (d) Abrasion–fibrosis amount; (e) Abrasion–PZ thickness; (f) Abrasion–vascular density. C: Calcification; CZ: Cellular zone; F: Fibrosis; PZ: Peripheral zone; VD: Vascular density; WZ: Weil zone