Clinicopathological Correlation of Pulp Stones and Its Association with Hypertension and Hyperlipidemia: An Hospital-based Prevalence Study.

INTRODUCTION: Pulp stones are the discrete calcification, located in pulp tissue or attached to or embedded in dentin. It occurs in physiological and pathological conditions. The exact etiopathogenesis of various types of pulp calcifications is unknown and the prevalence varies from 8% to 90%. The histopathological identification of pulp stones is higher than the radiological identification.
OBJECTIVE: The aim of the study is to evaluate and correlate the clinical parameters and histopathological analysis of pulp stone with systemic hypertension and hyperlipidemia.
MATERIALS AND METHODS: Seventy patients were selected for the study and a detailed case history was recorded. The radiological investigations were noted down and extirpated pulp tissues were sent for processing. The results were analyzed statistically using Chi-square test.
RESULTS: Out of 70 patients studied, pulp stones were observed radiologically in 14 patients and histopathologically in 30 patients. The presence of irregular and nonlaminated type of pulp stones histopathologically was significantly correlated with hypertension and hyperlipidemia.
CONCLUSION: The patients with the histopathological presence of nonlaminated and irregular-shaped pulp should be evaluated for lipid profile and hypertension. Copyright:

INTRODUCTION

The dental pulp is a highly fibrovascular tissue that resides in a rigid chamber comprising dentine, enamel, and cementum, which gives strong mechanical support and protection from the microorganism-rich oral environment.[1] Pulp stones are discrete or embedded calcified mass that occurs in both coronal and root portions of the pulp organ of any teeth in either maxilla or mandible, even in deciduous, permanent, erupted, and unerupted teeth.[23] They are the accidental finding in the routine radiograph and do not cause any symptoms until they impinge on a nerve.[4] They are classified based on their structure as true pulp stones (formed by dentin i.e., odontoblast) and false pulp stones (formed by the degenerated cells of the pulp) and based on location as free (fully surrounded by the pulp tissue), adherent (fused partially to the dentin), and embedded pulp stones (surrounded by dentin).[5] Although the exact cause of the pulp stones is unknown, it is caused by long-standing local irritants, trauma, caries, orthodontic tooth movement, systemic diseases, increasing age, hypervitaminosis, fibrosis, alteration in the pulpal circulation, wasting diseases, periodontal diseases, remnants of epithelial rests, genetic predisposition, and idiopathic factors, etc.[6] This un-mineralized pulpal tissue upon irritation results in inflammation and if unattended may eventually result in pulpal necrosis and calcification.[7]

Appleton and Williams recorded the histopathological patterns of pulp stones into those with distinct concentric laminations and without.[89]

Ashley and Liewehr (2006) histologically recognized two varieties of pulp stones that are spherical or ovoid, with smooth surfaces and concentrical laminations and others with no specific form, lack laminations, and rough surfaces.[1011]

Several studies suggest the correlation between the presence of pulp stones identified in radiographs and cardiovascular disease [Table 1].

Table 1

Pulp stones and systemic disease[12131415161718]

Author details	Method of analysis	Interpretation
Garima Yeluri et al., 2015	Digital panoramic radiography and ultrasonography	Presence of pulp stones and positive correlation with cardiovascular disease and renal disease
Bains et al., 2014	Intraoral periapical radiographs	Patients with pulp stones have a high propensity to develop cardiovascular or cholelithiasis
Horsley et al., 2009	Digital panoramic radiography	Both pulp and carotid calcifications were more prevalent in older individuals
Edds et al., 2005	Radiographs	The association between pulp stones and cardiovascular disease is of significance
Khojastepour et al., 2013	Digital panoramic radiographs	Patients with CVD show an increased incidence of pulp calcification compared with healthy patients
Panwar, et al., 2019	Bitewing radiographs	Posterior teeth had an increased amount of calcification and are related to coronary artery disease
Nayak et al., 2010	RVG	Positive correlation was found between systemic disorder and pulp stones. Cardiovascular patients had maximum number of pulp stones
Fatemeh Ezoddini-Ardakani et al., 2015	Digital panoramic radiographs	The ratio of teeth with pulp stone a good tool for early detection of CVD

Hypercholesterolemia is one of the major modifiable risk factors for cardiovascular disease. Lipids play a role in the initiation of hydroxyapatite formation and may influence the development of arterial calcification, hypertension, and cardiovascular disease.[1920] However, the presence of pulp stones and their significance with hypertension and hyperlipidemia is still inconclusive in literature. Therefore, we have aimed primarily to study the histopathological presence of pulp stones in patients undergoing endodontic treatment and to evaluate hypertension and total serum cholesterol being the secondary aim.

Aim

The purpose of this study is to evaluate the various parameters such as age, gender, tooth involved, dental caries, trauma with radiological, and histological features of pulp stones. The secondary objective is to study the correlation of histological findings of pulp stones with systemic hypertension and hyperlipidemia.

MATERIALS AND METHODS

After obtaining ethical clearance from Institutional Review Board, Institutional Ethical Committee, and the informed consent from patients, the study was conducted at the Department of Oral Pathology CSI College of Dental Sciences and Research, Madurai. The analytical study was carried out with a sample size of 70 patients who were selected through a random sampling method, whose age range was 9–65 years, and patients who were undergoing root canal treatment.

Inclusion criteria

Patients who are undergoing root canal treatment

Permanent dentition.

Exclusion criteria

Tooth with developmental anomalies

Periodontally weak tooth.

A detailed case history with parameters such as age, gender, dental caries, history of trauma, and the presence of systemic disease like hypertension (American Heart Association Guidelines, 2017) was recorded. Blood samples were collected from the patients who had Stage II hypertension to evaluate the total serum cholesterol. The patients who measured with values above 190 mg/dl (American College of Cardiology guidelines 2018) were considered as hyperlipidemia. The intraoral periapical radiographs were analyzed to study the presence or absence of pulp stones. The pulp tissues extirpated from the patients who were undergoing root canal treatment were collected and fixed in 10% formalin. The tissues were processed and 4-μ sections were made through the semi-automatic microtome. The sections were stained with hematoxylin and eosin and examined under Olympus Trinocular Research Microscope model BX 53.

Statistical analysis

The information collected regarding all the selected cases was recorded in a Master Chart using an Excel sheet. Data analysis was done with the help of a computer by using SPSS 16 software. Using this software, percentages, means, standard deviations, and values were calculated through Student t-test for raw data and Chi-square test for consolidated data to test the significance of difference between variables, a value <0.05 is taken to denote significant relationship.

RESULTS

Out of 70 patients, the mean age was 34.14 years standard deviation ± 11.4. Seventy samples comprised 50 (71%) cases in maxillary teeth and 20 (29%) cases in mandibular teeth, and the presence of caries was observed in 46 cases (65%) and history of trauma in 24 cases (35%) [Table 2].

Table 2

Case distribution of the pulp stones

Clinical parameters (n=70)	Results, n (%)
Age
Minimum: 35–<40	34 (48.5)
Maximum: 65–≥40	36 (51.4)
Gender
Male	38/70 (54)
Female	32/70 (46)
Pulp stones
Present	30/70 (43)
Absent	40/70 (57)
Site
Maxilla	50/70 (71)
Present	20/50 (40)
Absent	30/50 (60)
Mandible	20/70 (29)
Present	10/20 (50)
Absent	10/20 (50)
Dental caries	46 (65)
Present	14/46 (30)
Absent	32/46 (70)
Dental trauma	24 (35)
Present	16/24 (67)
Absent	8/24 (33)
Histological presence of pulp stone	30 (43)
Histological presence of Inflammation	14 (20)
Radiographical presence of pulp stone	14 (20)

Pulp stones were seen histologically in 30 patients (43%), whereas in the radiographic examination the occurrence of pulp stones was seen in 14 (20%). The presence of pulp stones was observed in 14 (30%) teeth with caries and 16 (67%) cases had trauma [Table 3].

Table 3

Clinical parameters and its correlation with the pulp stones

Clinical parameters	Total number of cases (n=70)	Presence of pulp stones	Absence of pulp stones	χ 2	P
Age
<40	34	2	32	5.002	0.08
≥40	36	28	8
Gender
Male	36	16	20	0.038	0.845
Female	34	14	20
Site
Maxilla	50	20	30	0.292	0.589
Mandible	20	10	10
Location
Anterior	50	20	30	0.292	0.589
Posterior	20	10	10
Clinical factors
Caries	46	13	33	6.23	0.044
Trauma	24	17	7
Radiographic interpretation
Present	14	14/30	0	1.680	0.195
Absent	56	16/30	40
Root canal treatment
Intentional		2/30	28/30	0.044	0.833
Routine endodontic therapy		28/30	2/30
Inflammatory cells
Present		14/30	16/30	35.000	0.000
Absent		16/30	14/30
Hypertension	22	18	04	35.000	0.000
Number of pulp stones
Single		18/30	12/30	35.000	0.000
Multiple		12/30	18/30
Shape of pulp stones
Spherical/ovoid		14/30	16/30	35.000	0.000
Irregular		16/30	14/30
Pattern of pulp stones
Laminated		08/30	22/30	35.000	0.000
Nonlaminated		22/30	08/30

Histological analysis revealed a chronic inflammatory response in 18 (80%) cases. Based on the number of pulp stones observed, single pulp stones were seen in 18 (26%) cases and multiple pulp stones in 12 (17%) [Figure 1a and d] cases. Based on the shape of the pulp stone, spherical shape was seen in 14 (20%) cases and irregular shape [Figure 1b and e] was seen in 16 (23%) of cases. Based on the pattern, laminated pulp stone was observed in 6 (9%) cases and nonlaminated pulp stone was observed in 24 (34%) [Figure 1c and f] cases [Table 4 and Figure 2a and b].

Figure 1

(a-f) Pulp stones and its histological pattern

Table 4

Histological analysis of pulp stone and its comparison with hypertension

Histopathological analysis	Types	Number of pulp stones, n (%)	Hypertension, n (%)
Based on the number	Single	18/30 (60)	8/18 (44)
	Multiple	12/30 (40)	10/18 (54)
Based on the shape	Spherical	14/30 (47)	7/18 (38)
	Irregular	16/30 (53)	11/18 (62)
Based on the pattern	Laminated	06/30 (20)	4/18 (22)
	Nonlaminated	24/30 (80)	14/18 (78)

Figure 2

(a and b) Radiographic presence of pulp stones

The presence of pulp stones was observed in 18 cases (25%) who had hypertension and 16 cases (22%) who had increased serum cholesterol levels.

On statistical analysis, there is a significant association between age (P = 0.001), trauma, and caries with the presence of pulp stones (P = 0.003). Similarly, a significance of 0.001 was found when comparing hypertension, hyperlipidemia, and the presence of pulp stones. There is a significant correlation (correlation coefficient r = 1.00) between nonlaminated pattern of pulp stones with hypertension and hyperlipidemia. However, there is also a significant correlation (correlation coefficient r = 1.00) between the irregular shape of the pulp stones with hypertension and hyperlipidemia.

Pearson's Chi-square test of significance showed that there is a highly significant association between the incidence of pulp stones with the clinical parameters such as caries and trauma. Therefore, the role of perplexing factors such as genetics, food, environment, and water plays an important role in the etiology of pulp chamber narrowing. Histopathologic examination of the extracted teeth has also been used for evaluating the presence of pulp stone. There was a significant correlation between the inflammatory cells (P = 0.04) and the presence of pulp stones.

On histopathological evaluation of the pulp stones, there is a significant correlation with the number, shape, and pattern (P = 0.000). Focusing on the histology of pulp stones, the data analysis revealed that among all the patients, there was a significantly higher association between the presence of pulp stones and hypertension [Table 4 and Figure 1 and Graph 1]. Similarly, regarding the distribution of pulp stones, there was an increase in association between nonlaminated, multiple, and irregular patterns of pulp stones with that of hypertension.

Graph 1

Distribution of histopathological pattern among hypertensive patients

DISCUSSION

Several authors have described the pulp stones based on the number, size, and shape, but there was no apparent study available regarding the histological pattern. In this present study, we have classified histologically the pulp stones, based on the number, shape, and presence of laminations into single, multiple, regular, irregular, laminated, and nonlaminated patterns [Table 4].

In this present study, increasing age and history of trauma had a significant association with the detection of pulp calcification, and this is in accordance with earlier findings.[21] Furthermore, we have observed that the trauma having a significant association with pulpal calcifications could be attributed that pulpal response to trauma is more adverse than compared to dental caries.[2223] Therefore, in light of this present finding, continuous monitoring of traumatized teeth for any signs of pulpal inflammation is very crucial.[24]

The present study observed that pulp stone was significantly detected in histological examination than compared to radiograph observation.[25] This is similar to previous reports on pulp stones or calcification detection using radiographs.[26] The role of histological presence of pulp calcification in hindering the cleaning and shaping of root canal system needs to be explored in future studies.

Moss-Salentijn and Klyvert studied the pulp stones using radiographic criteria.[2728] Further, Goga R described that the histological presence of pulp stones is slightly at a higher rate[12] because pulp stones with a diameter smaller than 200 μm cannot be seen on radiographs.

The studies that were done by various authors to find the significance of hypertension and cardiovascular disease along with the presence of pulp stones and their method of analysis are tabulated in Table 1.

Relevant literature search did not yield any information regarding the presence of pulpal calcification and its association with hypertension or hyperlipidemia. To the best of the author's knowledge, this is the first time a significant association between histological pattern of pulp calcification and hypertension and hyperlipidemia is reported. In the contemporary observation, we additionally did an evaluation to discover the correlation among the histopathological sample with hypertension and hyperlipidemia. There was a strong fine correlation (coefficient of correlation r = 1.00) among the nonlaminated sample and irregularly shaped pulp stones.

Arterial stiffening, which is related to hypertension, can play the main role in the calcification of vessels.[29] In hypertension, there are modifications in elastin fragments generation, elevated protease activity, and activation of transforming growth factor-β signals along with the deposition of collagen and proteoglycans which creates a perfect platform for vascular calcification irrespective of the age. Therefore, we assume that these calcifications can occur in any part of the body including the pulp leading to the formation of pulp stones.[30]

In addition, the association between hyperlipidemia and the presence of pulp stone is documented in the current study whose P = 0.001 that is consistent with Jose George et al. Lipids are recognized to play a role in both bone formation and bone resorption and it is involved in early bone mineralization at the level of nidus formation. The preliminary step in hydroxyapatite crystal formation in bone includes the generation of matrix vesicles, which act as nucleation sites. Matrix vesicles incorporate phospholipids, phosphoproteins, and alkaline phosphatase, which are thought to take part withinside the initiation of hydroxyapatite mineral formation.[3132] Modified lipoproteins stimulate calcification through improving osteogenic differentiation. Modified lipoproteins act via the scavenger receptor SRA 1 to inhibit vascular smooth muscle cell phagocytosis of apoptotic bodies, consequently producing extra nidi for calcification.[33] Apoptotic bodies had been proven to build up calcium and calcify, suggesting that they may act as sites for calcium crystal nucleation. The accepted fact is the lipids that play a role in the initiation of hydroxyapatite formation, and statins modify bone remodeling, thus lipid metabolism may impact the development of arterial calcification; hence, we assume that the increased serum cholesterol may be the reason for pulpal calcifications.[34]

There is a strong correlation between irregular and nonlaminated pulpal calcifications with hypertension and hyperlipidemia. Further studies on massive samples have to be compelled to understand the pathologic process associated with it.

CONCLUSION

Clinicians often ignore the pulp stones that are unique lesions having importance in the long-term prognosis of the tooth as well as the systemic disease. In our study, there is a strong correlation between hypertension, hyperlipidemia, and presence of nonlaminated pattern of pulp stones; therefore, we insist that every extirpated pulp tissue should be subjected to histopathological examination to identify the pattern of pulp stones. The presence of nonlaminated pattern of pulp stones may be a predictor of hypertension and hyperlipidemia that should be confirmed in future by studying on a large scale.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.