2023 Volume 65 Issue 4 Pages 257-260
Purpose: To assess the prevalence and distribution of pulp stones in a Saudi population.
Methods: A cone beam computed tomography (CBCT) analysis of 150 upper and 150 lower dental arches was performed. The relationships between pulp stones and age, sex, tooth type, dental arch, orthodontic treatment, caries, and restoration were statistically examined (P < 0.05).
Results: A total of 295 dental arches (98.3%) had at least one pulp stone, and the prevalence was higher in the maxillary teeth (56.2%) than in the mandibular teeth (48.1%) (P = 0.0003). Men were more likely to have pulp stones than women (P = 0.011 for the maxilla, P < 0.0001 for the mandible). Furthermore, age and orthodontic treatment had no significant effects on the incidence of pulp stones (P > 0.05). A higher occurrence of pulp stones was observed in the first molars (>91%), and in carious and restored teeth when compared to intact teeth (P < 0.05).
Conclusion: Pulp stones were more prevalent in the upper dental arches, first molars, and carious and restored teeth, as well as in the male population, and were not associated with age or orthodontic treatment.
A pulp stone or denticle is a discrete calcified mass that can form within the pulpal cavity of a permanent or primary tooth. It can affect healthy, infected, impacted, or unerupted teeth [1]. Pulp stones are more frequently found in the pulp chamber and occasionally in the radicular pulp [2]. There is no definitive explanation for the etiology of dental pulp calcification; however, potential factors include periodontal disease [3], pulp degeneration [2], orthodontic tooth movement [4], and dental caries [5].
Pulp stones are broadly classified as singular or multiple; free, attached, or dentin-embedded; and true or false. True stones (dentin-like) have tubules surrounded by predentin and odontoblasts, whereas false stones are nontubular and composed of mineralized, degenerating cells [6]. The presence of higher cellular content in the coronal pulp and more fibrous tissue in the radicular pulp determines the nodular and diffuse mineralization patterns in these regions, respectively [7].
The presence of pulp stones is clinically important. Calcification can impede access during root canal treatment, and various studies have discussed the clinical management of such cases [8,9]. However, pulpal calcification is not an indication for endodontic therapy in the absence of other signs or symptoms [6]. In addition, pulp calcification has been proposed as a predictor of systemic conditions such as cardiovascular disorders [10,11].
Evidence indicates that pulp stone prevalence varies according to ethnicity, sex, age, and the presence of systemic conditions [11,12,13]. In general, pulp stone detection relies on periapical, bitewing, and panoramic radiographs. However, these two-dimensional techniques are only useful for identifying pulp stones larger than 200 μm in diameter; therefore, the actual prevalence is underestimated [14]. Three-dimensional cone beam computed tomography (CBCT) is widely used in complex dental procedures. Furthermore, CBCT provides additional information and holistic images in all three orthogonal planes (axial, coronal, and sagittal) for a more accurate diagnosis and treatment planning [15]. In addition, CBCT imaging is advantageous for better visualization of pulp stones compared to conventional radiography [16].
Some previous studies have reported the prevalence of pulp stones in the Saudi Arabian population; however, only a few have used CBCT [11,17]. This study aimed to assess the prevalence and distribution of dental pulp stones in the Saudi population using CBCT. Furthermore, correlations between pulp stones and age, sex, tooth type, dental arch, orthodontic treatment, caries, and restorations were also examined.
Prior to the study, ethical approval was obtained from the Institutional Review Board of the Research Ethics Committee of King Saud University (IRB No. E-22-6854), and the study was registered at the College of Dentistry Research Center (CDRC No. FR0644). This retrospective study used patient records from the King Saud University Dental Hospital database, with no risk to human participants. The requirement for informed consent was waived owing to the retrospective nature of the study.
The study retrieved 852 CBCT images of the maxillary and mandibular arches, obtained between June 1, 2019, and May 31, 2022, for diagnostic and treatment requirements. A total of 300 combined CBCT images (150 maxillary and 150 mandibular arches) that fulfilled the inclusion criteria (Table 1) were used to investigate the presence of dental pulp stones. Definite single or multiple radiopaque structures observed in the entire pulp space were diagnosed as pulp stones. Two trained investigators confirmed the presence or absence of pulp stones in each tooth. Based on the kappa analysis of consistency between the examiners, the inter- and intra-examiner reliability values were determined as 0.88 and 0.9, respectively. Patients’ age, sex and history of orthodontic treatment were recorded.
Patient CBCT scans included in the study were obtained with a ProMax 3D Max machine (Planmeca, Helsinki, Finland) using the following settings: tube current, 12 mA; tube voltage, 90 kV; imagine time, 12 s; and isotropic voxel size, 0.2-0.16 mm. The field of views were fixed at 13 cm × 9 cm for maxillary arches, and 10 cm × 9 cm for mandibular arches. Individual CBCT images were displayed on a 34-inch LED screen in a dark room and screened using the Romexis software (Planmeca, Helsinki, Finland). The images of the teeth were analyzed in all planes (axial, sagittal, and coronal) (Fig. 1).
Descriptive statistics, frequencies, percentages, means, and standard deviations are presented. For statistical inference, a proportional t-test was used to evaluate the differences between two categorical variables. Independent t-tests and one-way analyses of variance were used to compare two or more groups based on their averages, respectively. Statistical analysis of the normality and homoscedasticity of variance tests were conducted. Kolmogorov and Shapiro-Wilk tests, as well as the central limit theorem, indicated normality within each age group. Based on the Levene statistical test, homoscedasticity of variance was satisfied for the different age groups being compared (P > 0.05). The level of significance was set at 0.05; any test with a P-value less than 0.05 was considered significant. The collected data were analyzed using SPSS version 25 (IBM, Armonk, NY, USA).
| Inclusion criteria | Exclusion criteria |
|---|---|
| Saudi patients aged ≥18 years | Patients <18 years |
| Clear CBCT images of maxilla or mandible | CBCT images with poor quality Missing teeth Third molars Teeth with: dental prostheses pulp treatment pulp pathology immature roots fracture |
Axial (A), sagittal (B and C), and coronal (D) CBCT views showing pulp stones (white arrows) in the root canals of different teeth
This study analyzed CBCT images of 150 maxillary and 150 mandibular dental arches, with a total of 3,858 teeth being assessed for the presence of pulp stones. Among these teeth, 1,905 (49.4%) were maxillary and 1,953 (50.6%) were mandibular, while 342 teeth were excluded (Table 1). The demographic data are presented in Table 2.
Out of the 300 dental arches examined, 295 (98.3%) had at least one pulp stone (P < 0.0001). The prevalence rates of pulp stones were 98.7% and 98% in the maxilla and mandible, respectively (Table 3).
Table 4 shows that 1,070 (56.2%) and 939 (48.1%) maxillary and mandibular teeth, respectively, were found to have pulp stones. Furthermore, the prevalence of pulp stones was significantly higher in the maxillary teeth than that in the mandibular teeth, as determined by a proportional t-test (P = 0.0003).
Table 5 shows the average number of pulp stones in the maxillary and mandibular teeth across different age groups, sex, and orthodontic treatment. The analysis indicated a significant difference in the number of teeth with pulp stones in men versus women (P = 0.011 for the maxilla, P < 0.0001 for the mandible), while age groups and orthodontic treatment showed no significant effect on the number of teeth with pulp stones (P > 0.05).
The distribution of pulp stones in each tooth type was also investigated. In both maxillary and mandibular teeth, the highest to lowest proportion of pulp stones were found in the molars, central incisors, canines, lateral incisors, and premolars. The percentage of pulp stones in each tooth type is presented in Table 6 and Fig. 2. The first molars showed the highest percentage of pulp stones in both arches (>91%), while premolars were the least affected (<31%).
The study also evaluated the relationship between pulp stones, and dental caries and/or fillings (Table 7). The proportional t-test demonstrated that the prevalence of pulp stones was significantly higher in carious teeth than in intact teeth (P = 0.001 for maxilla, P < 0.0001 for mandible). In addition, more than 65% of upper and lower teeth with dental fillings had pulp stones (P < 0.05). Pulp stones were more common when the teeth had a combination of dental caries and restorations (P < 0.0001).
| Variable | Number of dental arches examined (%) | |
|---|---|---|
| Dental arches examined (n = 300) | maxilla | |
| mandible | ||
| Teeth examined (n = 3858) | maxillary teeth (n = 1,905, 49.4%) | 150 (50) |
| mandibular teeth (n = 1,953, 50.6%) | 150 (50) | |
| Sex | men | 122 (40.7) |
| women | 178 (59.3) | |
| Age group (years) | 18-30 | 215 (71.6) |
| 31-40 | 59 (19.7) | |
| ≥41 | 26 (8.7) | |
| Orthodontic treatment | yes | 129 (43) |
| no | 171 (57) | |
| Dental arch | Pulp stones | P | |
|---|---|---|---|
| yes n (%) |
no n (%) |
||
| Maxilla (n = 150) | 148 (98.7) | 2 (1.3) | <0.0001 |
| Mandible (n = 150) | 147 (98) | 3 (2) | <0.0001 |
| Total (n = 300) | 295 (98.3) | 5 (1.7) | <0.0001 |
Proportional t-test
| Dental arch | Teeth examined | Pulp stones | |
|---|---|---|---|
| yes n (%) |
no n (%) |
||
| Maxilla | 1,905 | 1,070 (56.2) | 835 (43.8) |
| Mandible | 1,953 | 939 (48.1) | 1,014 (51.9) |
| Total | 3,858 | 2,009 (52.1) | 1,849 (47.9) |
Proportional t-test comparing maxillary and mandibular teeth (P = 0.0003)
| Variable | Maxilla (n = 150) | P | Mandible (n = 150) | P | ||
|---|---|---|---|---|---|---|
| examined n (%) |
teeth with stones mean ±SD |
examined n (%) |
teeth with stones mean ± SD |
|||
| Sex | 0.011 | <0.0001 | ||||
| men | 62 (41.3) | 7.87 ± 2.64 | 60 (40) | 7.55 ± 2.77 | ||
| women | 88 (58.7) | 6.65 ± 2.97 | 90 (60) | 5.38 ± 3.07 | ||
| Age group (years) | 0.921 | 0.362 | ||||
| 18-30 | 112 (74.7) | 7.10 ± 2.77 | 103 (71.7) | 6.49 ± 3.20 | ||
| 31-40 | 27 (18) | 7.00 ± 2.79 | 32 (21.3) | 5.63 ± 2.95 | ||
| ≥41 | 11 (7.3) | 7.40 ± 2.73 | 15 (10) | 5.93 ± 2.73 | ||
| Orthodontic treatment | 0.123 | 0.685 | ||||
| yes | 67 (44.7) | 7.54 ± 2.86 | 62 (41.3) | 6.37 ± 3.39 | ||
| no | 83 (55.3) | 6.84 ± 2.65 | 88 (58.7) | 6.16 ± 2.96 | ||
Independent t-test for gender and orthodontic treatment; one-way analysis of variance for age group. SD, standard deviation
| Side | Tooth type (number) | Teeth examined (n) | With pulp stone n (%) |
|---|---|---|---|
| Maxillary teeth | |||
| Right | second molar (17) | 144 | 115 (79.9) |
| first molar (16) | 124 | 114 (91.9) | |
| second premolar (15) | 119 | 29 (24.4) | |
| first premolar (14) | 140 | 23 (16.4) | |
| canine (13) | 140 | 76 (54.3) | |
| lateral incisor (12) | 138 | 66 (47.8) | |
| central incisor (11) | 144 | 105 (72.9) | |
| Left | central incisor (21) | 143 | 104 (72.7) |
| lateral incisor (22) | 142 | 66 (46.5) | |
| canine (23) | 142 | 76 (53.5) | |
| first premolar (24) | 135 | 29 (21.5) | |
| second premolar (25) | 118 | 28 (23.7) | |
| first molar (26) | 133 | 122 (91.7) | |
| second molar (27) | 143 | 117 (81.8) | |
| Mandibular teeth | |||
| Left | second molar (37) | 134 | 111 (82.8) |
| first molar (36) | 118 | 110 (93.2) | |
| second premolar (35) | 132 | 38 (28.8) | |
| first premolar (34) | 145 | 44 (30.3) | |
| canine (33) | 148 | 56 (37.8) | |
| lateral incisor (32) | 148 | 51 (34.5) | |
| central incisor (31) | 149 | 62 (41.6) | |
| Right | central incisor (41) | 149 | 65 (43.6) |
| lateral incisor (42) | 149 | 51 (34.2) | |
| canine (43) | 148 | 57 (38.5) | |
| first premolar (44) | 145 | 41 (28.3) | |
| second premolar (45) | 129 | 33 (25.6) | |
| first molar (46) | 117 | 108 (92.3) | |
| second molar (47) | 142 | 112 (78.9) | |
Pulp stone distribution according to the tooth number in the (a) maxillary and (b) mandibular teeth
| Examined n |
Maxillary teeth with stone n (%) |
P | Examined n |
Mandibular teeth with stone n (%) |
P | |
|---|---|---|---|---|---|---|
| Caries | 712 | 411 (57.7) | 0.001 | 595 | 299 (50.3) | <0.0001 |
| Filling | 61 | 40 (65.6) | 0.016 | 44 | 30 (68.2) | 0.042 |
| Caries and filling | 310 | 211 (68.1) | <0.0001 | 305 | 224 (73.4) | <0.0001 |
| Intact teeth | 822 | 408 (49.6) | - | 1009 | 386 (38.3) | - |
| Total | 1905 | 1070 | 1953 | 939 |
Proportional t-test; variables compared to intact teeth
This retrospective study aimed to assess the prevalence and distribution of dental pulp stones in a Saudi population using CBCT images of the maxillary and mandibular arches. Additionally, this study examined the correlation between pulp stones and various factors such as age, sex, dental arch, tooth type, orthodontic treatment status, caries, and fillings. Although conventional radiography has been used in numerous pulp stone studies [4,13,18,19], it has several limitations. The method only detects calcified structures >200 µm in diameter, implying that the true prevalence of pulp stones is likely higher [20]. Although histological surveys have shown an increased prevalence of pulp stones, this invasive technique requires tooth extraction and is limited to a small number of sections, resulting in underestimation [6,21].
Recently, it has become common practice to perform complex dental procedures using CBCT, which provides greater specificity, accuracy, and resolution than the conventional imaging techniques. In addition to offering improved visualization of pulp stones over conventional radiographs, CBCT imaging is less invasive than histological examination [12,16].
Several studies have examined the prevalence of pulp stones in permanent teeth, with results ranging from 8% to 95% [18]. In contrast, the current study showed that pulp stones were present in 98.3% of the dental arches (Table 3) and in 52.1% of the teeth (Table 4). Several factors may have contributed to the higher prevalence in this study as compared to the previous investigations. For example, this study examined the entire pulp space, including the pulp chamber and root canal space, whereas other studies only examined the pulp chamber [22,23]. Furthermore, most previous studies used two-dimensional radiographs, which provide less accurate and less detailed information as compared to CBCT imaging modalities [13,24,25]. A recent study on a Taiwanese population using CBCT revealed a high prevalence of pulp stones (83.3% of subjects and 31.3% of the total number of teeth) [12], but it remained lower than that for the present study, which may be owing to differences in ethnicity and methodology. Also, in contrast to the Taiwanese study that estimated the prevalence of pulp stones in both dental arches using a larger field of view (FOVs) for both dental arches [12], the present study examined CBCT images using smaller FOVs for single dental arches. According to Elshenawy et al. (2019), smaller FOVs may be associated with higher CBCT accuracy than larger FOVs [26]. In a previous Saudi study that excluded teeth with dental caries and restorations, a lower prevalence of pulp stones in both patients and teeth was reported [11]. However, the present study included teeth with caries and fillings, which accounted for a substantial proportion of the total number of teeth examined (Table 7).
The findings of the current study are in line with those of several previous studies, indicating that pulp stones are more common in the maxilla than in the mandible [11,12,27]. However, other studies have reported conflicting results, with some reporting a similar prevalence of pulp stones in both dental arches [21], while others have found a higher prevalence in the mandibular teeth [24]. Therefore, larger-scale studies are required to further investigate these discrepancies.
Researchers investigating the prevalence of pulp stones in men and women have produced inconsistent results. In the present study, the results demonstrated a higher prevalence of pulp stones in men in both the upper and lower dental arches, which may be attributed to the increased prevalence of pulpal inflammation in men [28]. However, other studies have reported contradictory findings, indicating that women are more likely to develop pulp stones due to factors such as increased bruxism [19] and hormonal changes [13]. Furthermore, one study found no significant sex differences in the occurrence of pulp stones [16].
Age did not significantly affect the frequency of occurrence of pulp stones, which is in agreement with a previous study [12], but conflicts with others [13,17,19]. According to a previous study, aging alone is not a primary factor for pulp calcification [24]. It is possible that the discrepancy in results is due to age-related factors, such as continuous dentinogenesis, which may reduce the number of pulp stones by completely integrating pulp stones into the dentinal mass. On the contrary, continuous irritation of dental pulp (e.g. caries) [6] and chronic diseases (e.g. diabetes) [11] that are more prevalent with increasing age pose a higher risk for the development of pulp stones.
In contrast to the findings of a retrospective clinical follow-up study [4], no link was observed between orthodontic treatment and the formation of pulp stones. This discrepancy may be attributed to differences in age, sample size, types of teeth examined, and the timing and type of orthodontic treatment performed.
In terms of tooth type, a similar trend of pulp stone prevalence was observed as in a previous study, with the highest incidence observed in molars, followed by central incisors, canines, lateral incisors, and premolars [12]. Within the maxillary and mandibular arches, the first molars had the highest incidence of pulp stones, possibly owing to the larger pulp space and tissue volume, as well as ample blood supply, which contributed to a higher risk of calcification [11,12].
Consistent with other research, pulp stones were more prevalent in carious and restored teeth than in intact teeth [16,19,27]. In addition, this prevalence was higher when the teeth had a combination of irritants (caries and restorations). Evidence suggests that pulp stones may develop as a defense mechanism in response to chronic irritants such as dental caries and restorations [27].
Finally, the present study has several noteworthy limitations. First, the design of the study did not allow for the evaluation of pulp stones in both the maxillary and mandibular dental arches of the same patients due to limited availability of CBCT images for both arches. However, this drawback may have contributed to the enhanced accuracy of CBCT images, as discussed earlier. Second, the study was conducted using a limited sample size from a single dental hospital. As different populations may have varying prevalence of pulp stones, this limitation should be noted. Accordingly, it is highly recommended to perform a multicenter investigation across various geographical regions in the country, using a larger sample size, to further explore the prevalence of pulp stones and associated risk factors.
In conclusion, using CBCT, the prevalence of pulp stones was 98.3% in the dental arch and 52.1% in teeth. Pulp stones were more commonly found in the maxillary teeth than in the mandibular teeth, in men, and in carious and restored teeth, with first molars being the most commonly affected. However, no association was found between the presence of pulp stones and age or orthodontic treatment. Furthermore, CBCT provides a valuable tool to accurately detect pulp stones with three-dimensional anatomical details. Finally, dentists should be aware of the prevalence of pulp stones and their associated predisposing factors.
The authors have no conflicts of interest to declare, and there is no financial interest to report.
The authors wish to thank the College of Dentistry Research Centre and the Deanship of Scientific Research at King Saud University, Riyadh, Saudi Arabia, for funding this research project.
