Idiopathic dental pulp calcifications in a tertiary care setting in South India.

BACKGROUND: Dental pulp calcifications are unique and represent the dental pulp regenerative process. Dental pulp calcifications are sometimes routine findings in oral radiographs and may later serve as an important diagnostic criterion for a hidden aspect of systemic illness.
OBJECTIVE: The purpose of this study was to assess the patterns and prevalence of idiopathic dental pulp calcifications in a tertiary care setting in South India.
MATERIALS AND METHODS: A total of 227 patients were included in the study fulfilling the inclusion criteria. Age range of the study population was from 15 to 70 years. Teeth were examined under digital panoramic radiograph. The presence or absence of pulp stones was recorded. The presence of pulp stone were categorized according to the types classified as Type I, Type IA, Type II, Type IIA, Type II B, and Type III. The frequency of occurrence of pulp stones with sex, tooth type, dental arches, and types were compared with the types of calcification.
RESULTS: Total no. of patients with pulpal calcification were 227 [females 133 (58.59%) and males 94 (41.40%)]. The most common type between both sexes was Type I (48%). Total no. of teeth with calcification was 697; maxilla (48%), mandible (52%). The prevalence of pulp stone was found to be higher in the molars in both the arches. Most no. of pulp stones are reported at the third and fourth decade of life.
CONCLUSION: Idiopathic dental pulp calcifications are incidental radiographic findings of the pulp tissue and also may be an indicator of underlying disease.

INTRODUCTION

Dental pulp calcification occurs in all age groups with an increase in frequency in older age groups and in those teeth where there is an insult to pulp. Etiological factors for pulp stone formation are not well understood, although some factors that have been implicated in stone formation include pulp degeneration, inductive interactions between epithelium and pulp tissue, age, circulatory disturbances in pulp, orthodontic tooth movement, idiopathic factors, and genetic predisposition. The dental pulp calcification presents as masses of calcified tissue present on the level of the pulp chamber and roots of the teeth[1-5].

The formation of pulp stones has also been associated with long-standing irritants such as caries, deep fillings, and chronic inflammation. Despite a number of microscopic and histochemical studies, the exact cause of such pulp calcifications remains largely unknown.[6] A recent study focus the relationship of dental pulp calcification and nanoparticle and nanobacteria, but it is insufficient to tell about the exact etiology.[7] A few studies have shown the link between dental pulp stone and prevalence of kidney stone, and some others in relation to carotid calcification.[89] Here, in our study, we have tried to collect the data from the calcification in subjects where the causes were seldom found. We named the calcification as idiopathic dental pulp calcification, where the etiologic factors likes caries, restoration, filling, orthodontic tooth movement, and any history of trauma was excluded.

MATERIALS AND METHODS

Study subjects were those seeking panoramic radiographs and IOPAR (intra-oral periapical radiograph) at the department of Dento-maxillo-facial radiology. Study period was September 2011-February 2012. It was a prospective study; subjects included were those who were having pulp calcification in their routine intra-oral radiographs and in the panoramic radiographs. Ethical clearance was obtained for this study (IEC/22/2012). Informed consent from each patient has been obtained, especially regarding the radiation exposure. When the IOPAR alone was advised for various dental treatment in patients where idiopathic dental pulp calcification was found, panoramic radiographs were advised to rule out the presence of dental pulp calcification in other teeth. Subjects with crowns, bridges, caries, orthodontic treatment, bruxism, attrition, and traumatic teeth were not included in the study sample. Considering that teeth with deep fillings and caries lesions are more prone to have pulp stones, only teeth which were non-carious and unrestored were included. Children below the age of 10 years were excluded from the study. The radiographs were interpreted by two examiners using a standard viewing box with ambient light. Those taken at the wrong angulations, inappropriate exposure, and processing faults were excluded. Definite radiopaque bodies observed inside the pulp chambers and root canals of the all the teeth were identified as pulp stones and were scored according to the types classified [Figure 2, Table 1]. Attempts were made to determine the details of the pulp stones, such as types as specified and location in the pulp chamber root canal. To ensure of the accuracy of the diagnosis, only the teeth that were confirmed by our two examiners to have pulp stones were scored as present. Those teeth about which both our examiners were unsure were re-examined by our senior dental radiologist and scored according to his diagnosis. SPSS 13 was used, and descriptive statistics were determined, including the patient's age and gender, and the location, types, and arch of the pulp stones. Study subjects were asked about the status of any drug intake, any systemic disease, and previous treatment for any disease. Chi-square test was used to correlate the relationship between the types of pulp stones and cardiovascular disorders, diabetes mellitus, and other systemic disease.

Figure 2

Types of dental pulp calcification

Table 1

Classification of dental pulp calcification

RESULTS

Types of calcification in maxilla and mandible

Total number of teeth presented with calcification in maxilla and mandible was 697 [Figure 1]. In maxilla alone, the number of teeth presented with calcification was 334 (49%), the number calcification in the study was slightly more in the mandible (52%) than in maxilla (49%). In the maxilla, most commonly occurring type was Type I with a frequency of 214 (64.7%). Other types of pulp stones i.e., Type IA, Type II B were also seen, with the frequency of 32, 22 (9.58%, 6.58%), respectively. Both Type II and Type III occurred with a frequency of 26 (7.78%). Least commonly seen type was Type IIA, with frequency of 14 (4.19%).

Figure 1

Types of calcification in maxilla and mandible

In mandibular arch, the total no. teeth presented with calcification were 363 (52%); here also, the most commonly occurring type was found to be Type I with frequency of 168 (46.28%). The second most common type was Type IA with 76 (20%) cases. Other types like Type IIB, Type III, and Type II were seen with frequency 50 (13%), 39 (10%), and 27 (7%), respectively, and least common was Type IIA where only 3 cases were reported.

The occurrence of pulp stones was higher in mandible than in maxilla, and the commonest type observed in both the arches was Type I. In maxilla, the number of calcification with Type I is more than in the mandible with a frequency of 214 (64.7%). The frequency of Type I in both arches was 382 (54%), making the most common type of calcification in the study. The second most common type of calcification in the study was Type IA with a frequency of 108 (15%), with a least type of calcification of Type IIA in both the arches 17 (2.4%). The types II, IIB, and III occurred with a frequency of 53 (7.6%), 77 (11%), and 65 (9.3%).

Patterns of different types of calcifications according to age groups

The age range of the subjects included in this study was 15-70. Most number of pulp stones reported was at the third decade of life. 130 (44.98%) cases were reported in the age range of 21-25. 65 cases were Type I, 23 cases were Type IA, 19 cases were Type II, 9 cases were Type IIB, 10 cases were Type III. Type I was found to be most prevalent of all types and Type IIA being the least prevalent one, only 5 cases were found. About 45 (15.57%) cases were reported under the age group 26-30; here also, increased incidence of Type I was observed, and the least common was Type IIA. Type IIB has an equal predilection for the 21-25 age groups and 26-30 age groups. Most of the patients showed more than one type of pulp stone. In the present study, younger age groups showed increased prevalence of pulp stone. The majority of the patients included in this study were in the third decades of life, and we had only few patients older than 50 who have satisfied the inclusion criteria [Figure 3].

Figure 3

Patterns of different types of calcifications according to age groups

Gender and types of calcification

Total no. of patients with pulpal calcification was 227 [females 133 (58.59%) and males 94 (41.40%)] [Figure 4]. Between both sexes, females showed increased incidence of pulp stone. When multiple types of pulp stone was encountered in same individual, it was counted separate. The most common type between both sexes was type I (48%), in which a total of 82 (28%) females and 57 (19%) males were identified. Types like Type IA, Type IIB, and Type III were also found with increased frequency of pulp stones among the female patients. Among male patients, the frequency of Type IA, Type IIB, and Type III was 17, 9, and 7, respectively. While in female patients with the same types of pulp stones reported with increased frequency 38, 19, and 19. Least common type was Type IIA, with the frequency of 1 and 4 in males and females, respectively.

Figure 4

Patterns of different types of calcifications according to age groups

Number of teeth that presented with calcifications in the mandibular arch and maxillary arch according to the types of calcification

In mandibular arch, pulp stone was found to be higher in the first molars and second molars, and same type of pulp stone is seen bilaterally [Figure 5]. Among the 363 teeth examined, about 176 (48%) first molars, 118 (32%) second molars were involved. The least commonly involved were incisors with a frequency of 8 (2%). Type I variety was the most commonly involved [Figures 6, 7, 8], and the least prevalent was Type IIA.

Figure 5

(a) Histopathological section of dental pulp in Mallory stain showing dental pulp calcification (Photo courtesy Dr Jubin and Dr Mayeesh, department of oral pathology) (b) Specimens of dental pulp calcification, (c) Panoramic radiograph showing idiopathic dental pulp calcification in all the teeth including the impacted teeth. (d) Panoramic radiograph showing idiopathic dental pulp calcification in molar teeth

Figure 6

A -Type III dental pulp classification. B -Type I A dental pulp classification

Figure 7

A -Type I A dental pulp classification, B -Type I dental pulp classification

Figure 8

A -Type II dental pulp classification, B -Type I A dental pulp classification. C -Type II B dental pulp classification

In maxillary arch, the most commonly involved tooth was second molars and first molars. Bilateral presentation of the same types of pulp stones was also noted. Among 334 cases, 130 (38%) cases were found in the maxillary second molars and 114 (34%) cases were found in the first molars, respectively. Type I variety was the most commonly involved.

The association of idiopathic dental pulp calcification with systemic disease

Subjective assessment of the systemic disease in patients who were affected with idiopathic dental pulp calcification was also done. There were 23 patients who at some point of time had undergone treatment for kidney stones; 30 patients who were taking treatment for diabetes, 4 hypertensive patients, and 3 cardiac patients [Table 2].

Table 2a

Patients who have at some point of time had undergone treatment for kidney stones. There was a statistical significant among the patients who have undergone treatment for kidney stones and the type of calcification, P=0.001

DISCUSSION

The study was undertaken to assess the pattern and prevalence of idiopathic dental pulp calcification in a tertiary care setting. In the study, we tried to collect the data from the dental pulp calcification in subjects where the causes like caries, orthodontic treatment, bruxism, attrition, and traumatic teeth are seldom found. We named such calcifications as idiopathic dental pulp calcifications.

While correlating with other studies, our study has included a classification and typing of pulp stone. We evaluated the pulp stone with digital panoramic radiograph so that teeth involved with calcification in both maxilla and mandible can be ruled out. Review of the literatures reveals a wide discrepancy in the prevalence of pulp stones in different populations. This difference resulted from the variation in sample and sample size in previous studies. Furthermore, the presentations of prevalence were also different in the literature. Some investigations presented the prevalence based on person and teeth numbers, and the others reported only the prevalence based on teeth number.[10-12] The results of the present study in south Indian population showed a total no. of patients with pulpal calcification was 227 [females 133 (58.59%) and males 94 (41.40%)]. Between the both sexes, females showed increased incidence of pulp stone. The most common type between both sexes was type I (48%); a total of 82 (28%) females and 57 (19%) males were identified. However, some investigators have reported that pulp stones were more common in males than in females, and pulp stones occurred more frequently in the males than in females, whereas there are also studies showing no significant differences between both sexes.[11-13] These contradictory findings may be explained by marked differences in the sample size and in the methods used.

The age range of the subjects included in this study was 15-70. Most no. of pulp stones reported comes under the age group between 21 and 25. This indicates that the incidence of pulp stone was more in the younger age group, and shows that the aging and reactive changes alone is not the contributing factor for the pulp calcification. One of the studies has shown the importance of carotid calcification and pulp stone, and the study subjects were more in the third and fourth decade of life; our study contradicts the findings of the other studies when age alone is considered.[8] And our finding is similar to recent reports on a Iraq teenagers and Turkish population.[1314]

Total no. of teeth presented with calcification in maxilla and mandible was 697. In maxilla alone, the number of teeth presented with calcification was 334 (49%). In this study, the number of calcifications was slightly more in the mandible (52%) than in maxilla (49%). Also, there was equal distribution and presentation in both the sides of the arch in mandible and maxilla irrespective of the type of calcification. However, previous studies could not highlight right or left side occurrence.[1213]

Although many studies have been carried out to explore the prevalence of pulp stones, they have differed methodology, and many prevalence studies have identified pulp stones using radiographic criteria. The true prevalence is likely to be higher than Figures from these studies, because pulp stones with a diameter smaller than 200 μm cannot be seen on radiographs.[1516] In the present study, in maxillary arch, the most common involved teeth were second molars and first molars, and in the mandibular arch also, it was the first molars and second molars. The reason for this is unclear, but Ranjitkar et al. alluded that molars, being the largest in the arch, may have a better blood supply to the pulp tissues, which may not be conducive for precipitation of more calcifications-forming factors.[10-12]

The older clinical view is that pulp stones have no significance other than possibly causing difficulties during endodontic therapy, such as hindering canal location and negotiation,[17] Here, in our study, one patient has reported with intermittent pain on the tooth affected with calcification, and in 4 patients, there were discoloration.

Recently, it was reported that the importance of calcified nanoparticle and dental pulp calcification is one of the reason for the cause; the study says from the view of the particles located in the cytolysosome; the calcified nanoparticles could invade human dental pulp through a receptor-mediated endocytosis.[1819] The formation of pulp stones is still something of an enigma. Studies show that a high frequency of cell islands, considered to be of epithelial origin, were observed together with pulp stone formation in teeth that had been subjected to experimental intrusion.[2021] Yang et al. detected vacuoli containing mineralization crystals, which indicated the cell's tendency for crystal deposits. He inferred that the existence of calcified nanoparticles might promote the calcification as crystallization of the nuclei, which leads to the formation of biogenic apatite structures or mineralization degeneration of the cells.[19]

Patients were screened for the presence of any systemic disease; less than 10% of patients had taken treatment for kidney stone at some point of time, and also, these cases were in the third and fourth decade of life. In literature, the incidences of kidney stones are reported more at the third and fourth decade of life.[22] Again, the importance of the pulp stones, which are also reported at the third and fourth decade of life, serves as there any correlation with them.[22] May be the presence of pulp stone can be a predictive marker for kidney stone.[8] Yang et al. has suggested the importance of calcified nanoparticles and dental pulp calcification. Chen et al. has shown the relation of nanoparticle/nanobacteriae in nephrolithiasis.[23] And, there can be possible correlation between calcified nanoparticle and nephrolithiasis and idiopathic dental calcification. The limitations of the study were the small sample size, size of the calcification is not mentioned, and the calcification could vary from a very smaller size to larger one.

CONCLUSION

Though these incidental findings are seen in routine radiographs, they may serve as a potential premonition in prognosis of some systemic disease. The possible correlation with kidney stone and nanoparticles has to be studied. Larger population studies are needed to ascertain the significance of these idiopathic dental pulp calcifications.

Table 2b

Patient's food habit (Vegetarians and non-vegetarians) was correlated with the types of calcification, there was statistical significant, P=0.023

Table 2c

Systemic disease (Diabetes, hypertension, cardiac disease) and the types of calcification was correlated, there was no statistical significant, P=0.627