Introduction
The dental pulp is a soft tissue; the survival of which depends on the blood flow it receives and any change in this flow affects the health of the dental pulp.[ 1 ] In response to chemical or surgical stimuli, it may produce several types of calcifications to maintain homeostasis.
There are two chief morphological forms of pulp calcification - discrete (pulp stones) and diffuse calcifications. Pulp stones are calcified masses which are presented freely within the pulp or attached and embedded in coronal and radicular dentin.[ 2 ] Pulp stones are radiographically variable; they may occur as a single dense mass or as several small opacities within the pulp chamber or root canal.[ 3 , 4 ]
The etiological aspect of dental pulp stones and calcifications is vastly unknown, although several factors have been considered. There is a myriad of stimuli such as degenerative lesions, inductive interactions between epithelium and pulp, aging, other dystrophic soft-tissue calcifications, genetic predisposition, deranged blood circulation, and long-term irritation due to deep caries, restorations, and orthodontic tooth movements.[ 5 , 6 ]
These calcifications represent a phenomenon with the varied occurrence, presenting a topic of constant interest as they have a therapeutic aspect too. Although currently pulp stones are considered to have no clinical significance, the therapeutic aspect is of greater importance because during endodontic therapy, they can pose difficulties in accessing dental roots or sometimes make it completely impossible because the calcification may deflect or engage the tip of exploring instruments, preventing their easy passage down the canal.[ 7 ]
During orthodontic tooth movement, a series of complex tissue reactions take place which has an effect on dental pulp, alveolar bone, and supporting structures. Literature reveals that the force applied during orthodontic treatment may affect pulp in form of obliteration of pulpal tissue due to the formation of secondary dentin, internal root resorption, pulpal necrosis, as well as pulpal calcifications.[ 8 ]
Various studies have reported the incidence of pulp calcification in different types of teeth across several races and populations of society. The present retrospective study was planned and undertaken to study the prevalence of pulp calcification in known orthodontic patients using pre- and posttreatment panoramic radiographs . It also studied their correlation with age, gender, tooth type, dental arches, or location of occurrence. If any correlation is found to exist, it shall provide information to assist endodontists during root canal treatment of patients who have undergone orthodontic treatment in the past to avoid hindrances encountered during the treatment.
Materials and Methods
For the current retrospective study, a sample of 150 patients who had undergone orthodontic treatment in the Department of Orthodontics at Bhojia Dental College and Hospital, India, were selected.
Data acquisition
Panoramic radiographs were acquired from the patient records who had been treated between the years 2015 and 2021. The sample comprised 39.3% of males (59) and 60.7% of females, (91) age range 14–25 years at the beginning of the treatment [Figure 1 ].
Figure 1: Distribution of studied subjects as per gender
Panoramic radiographs of all the patients were obtained as a part of the diagnostic records required for orthodontic treatment ; therefore, patients were not subjected to unnecessary radiation. Informed consent was taken as part of the orthodontic treatment record. The average orthodontic treatment duration was 26 months (range 17–36 months).
Inclusion and exclusion criteria
We included pre and posttreatment panoramic radiographs for the study [Figure 2 ]. Panoramic radiographs of adequate quality, namely, density and contrast were only included. Panoramic radiographs of poor quality and teeth with caries, fillings, and crowns that prevented the evaluation of the crown were excluded. Patients who had previously undergone orthodontic treatment or had a positive medical history for any systemic diseases were excluded to avoid the impact of these factors on pulp calcification.
Figure 2: Pre- and posttreatment radiographs analyzed for observation of pulpal calcification. OPG: Orthopantomogram
Evaluation of radiographs and data recording
Posttreatment variables including gender, age (start of treatment), treatment duration, and pulp calcification were recorded. All fully erupted maxillary and mandibular molars were examined. Each tooth was analyzed on the collected panoramic radiograph for the presence of calcification coronally in the pulp chamber or in the root canal. Radiopaque, discrete ovoid calcifications in the pulp chamber and radiopaque, obliterated root canals were counted as a positive finding. The data were tabulated in MS-EXCEL followed by statistical analysis of the same.
Statistical analysis
SPSS package (SPSS for Windows, Version 19.0, manufactured by IBM, Chicago) was used to perform the analysis of the presented data. The frequency distribution of teeth with pulp calcifications was noted along with the change in the number of patients who presented with pulp calcification before and after the orthodontic treatment . The relation of pulp calcification with age, gender, tooth type, and dental arches was analyzed using Pearson’s Chi-square test. The presence of radicular and coronal calcification was also studied and presented in graphical form. The level of significance was P < 0.05 for all statistical analyses.
Results
Pretreatment panoramic radiographs indicated that 35.30% of patients had pulp calcification, whereas 50% of the patients had pulp calcification after orthodontic treatment [Figure 3 ]. Hence, statistical analysis showed that newly formed pulp calcification increased remarkably (14.7%) on the posttreatment radiographs (P < 0.05) following orthodontic treatment [Graph 1 ].
Figure 3: Presence of pulp calcification on posttreatment OPG wrt 37. OPG: Orthopantomogram
Graph 1: Frequency distribution of pre- and posttreatment calcification
There was an increase in pulp calcifications in 76 female and 50 male patients after the treatment, but there was no statistically significant difference between the genders in terms of pulp calcification enhancement (P > 0.05). The distribution of patients with pulp calcification during orthodontic treatment according to age was also studied. At the age of 17–19 years, 57 patients were detected with new pulp calcifications, and the highest value was observed in this age group. At the age of 20–22 years, the increase of pulp calcification was seen in 10 patients only and the least value was examined in this group. There was no statistically significant difference between the age groups (P > 0.05).
The pulp calcifications were found both in the coronal and radicular areas of the root canal system. Twenty-four percent of patients presented with radicular, dystrophic calcifications, 16% showed coronal calcifications in the form of pulp stones, whereas another 44% of patients presented with both radicular and coronal pulp calcifications [Graph 2 ].
Graph 2: Frequency distribution of radicular and coronal calcification
There were statistically significant differences between the incidence of calcifications among the mandible (109) and maxilla (70) (P < 0.05). Mandibular first molars exhibited pulp calcifications most frequently, followed by the mandibular second molars and maxillary first molars. The distribution of pulp calcification was higher in the first molars than second molars in both the arches and the relation of pulp calcification with tooth type was statistically significant (P < 0.05).
Treatment time was found to be related to posttreatment calcifications significantly. Among the groups of time taken for treatment completion (months), 29–32 months group showed maximum posttreatment pulp calcification, whereas the group of shortest time span, 17–20 months showed the least amount of pulp calcifications after orthodontic treatment [Table 1 ].
Table 1: Relation of treatment time with posttreatment calcification
Furthermore, there was no statistically significant difference between the right and the left sides or unilateral and bilateral occurrence of calcifications in the maxillary and mandibular arches on pre- and posttreatment panoramic radiographs .
Discussion
Over the due course of time, several reports have presented that orthodontic forces can be considered controlled trauma which induces various molecular and cellular changes in pulp-dentin complex, periodontal ligament, and alveolar bone.[ 9 ] In spite of detailed investigations to study this correlation, the physiology of tissue interactions still remains unclear.
Literature indicates varied data on the etiology of pulp calcifications which comprises pulp degeneration, age, idiopathic factors, genetic predisposition, circulatory disturbances in the pulp, orthodontic forces, healing, and repair.[ 10 ] Their formation may also be correlated to long-standing irritants such as caries, deep restorations, and chronic pulpal inflammation.[ 11 ]
There is conflicting literature regarding the association between the presence of pulp calcification and systemic disturbances. Edds et al . and Hoshyari et al ., in their studies, found that they were significantly related to systemic diseases such as coronary artery sclerosis and osteitis deformans.[ 5 , 12 ] Other diseases found to be associated with pulp calcification included type I diabetes, kidney disorders, Marfan sydrome, and familial expansile osteolysis.[ 13 ] On the other hand, Gulsahi et al . did not show any such correlation.[ 14 ] Therefore, the present study excluded patients with a positive medical history to prevent any bias due to systemic disorders.
Histological studies, as done by Javed et al ., have shown that major changes happen in the pulp after orthodontic treatment including impaired respiration, vacuolization, circulatory disturbances, hemorrhage, and even necrosis.[ 15 ] Contrary to these findings, literature can also be found which report changes in the pulp are not long-term after orthodontic forces are applied.[ 1 , 16 ] Orthodontic treatment involves the usage of varied fixed orthodontic appliances and the potential association between type of force/tooth movement and pulp calcification is still undetermined. While Stenvik and Mjör showed that orthodontic forces can cause pulp calcification, Ramazanzadeh et al . reported that there was no relation between pulp calcification and orthodontic forces.[ 17 , 18 ]
Pulp calcifications are not a predicted finding and are usually seen by coincidence on dental radiographs and can complicate endodontic treatment.[ 19 ] Histologic and radiographic examination can be done to check for their presence. The calcification must have reached a certain size (>200 micrometers) and mineralization to be detected during radiographic assessment.[ 14 , 20 ] To achieve a better three-dimensional picture, cone-beam computed tomography can also be used. However, it is a procedure which cannot be performed easily for every patient undergoing orthodontic treatment due to high radiation dosage and expenses. Hence, we evaluated the occurrence of pulp calcifications using digital orthopantomogram as they capture large data in a single image with low radiation dose.[ 21 ]
The occurrence of pulp calcifications has been reported to increase as a subject gets older in various studies.[ 12 ] To exclude such an effect of aging on pulp calcification, patients between the ages of 16 and 25 years were only included in this study.
In the mentioned sample, there were no significant differences between the two genders. This was found to be concordant with previous studies conducted by Ranjitkar et al . and Gulsahi et al .[ 14 , 20 ] However, several studies have also reported that pulp calcifications are more prevalent in females which could be due to women being more sensitive to higher stress levels and, consequently, the higher prevalence of bruxism.[ 22 ]
A more homogenous group of patients were selected regarding treatment time in this study. Patients who had undergone reasonably shorter (<17 months) or longer treatment (>36 months) than usual were not included. Further studies considering the effect of treatment duration on pulp stone formation should be designed.
Overall, molars are usually seen to have more pulp calcification. This has been attributed to the fact that molars are provided a better blood supply, which may cause calcification.[ 20 ] It has been shown that the incidence of pulp calcification can differ according to the dental arch and tooth type involved. Mostly, studies in the past have concluded that maxillary molars present with more pulpal calcifications.[ 14 , 18 ] However, according to the analysis of this study, a significantly high number of mandibular molars presented with pulp calcifications. Among the mandibular molars, the first molars were involved more than the second molars followed by the maxillary first and second molars.
The aspect of the location of pulp calcification was included in this study which has not been mentioned frequently in the literature. It was noted that maximum calcified teeth posttreatment presented with either radicular calcification alone or both radicular and coronal. The incidence of coronal calcification alone was found to be low which can be attributed to the fact that calcification almost always begins apically and extends coronally.
The limitation of this study was the absence of a control group to compare the difference between the orthodontically treated and untreated populations. Although an increase was observed in pulp calcification post orthodontic treatment in this study, further studies including a control group are required to determine a clearer relationship between pulp calcification and orthodontic treatment .
Conclusion
The results presented show that pulp calcification increased after orthodontic treatment in all tooth groups irrespective of subject’s age and gender. The maximum increment was detected in mandibular molars. It can be concluded that orthodontic treatment might affect the metabolism of the pulp and orthodontic forces may in turn increase pulp calcification. Therefore, the clinician must be aware of this pulp calcification increment in patients with a positive history of orthodontic treatment and perform a detailed radiographic examination before any endodontic treatment is undertaken.
Ethical statement
The study was approved by ethical committee at Bhojia Dental College, Baddi, Himachal Pradesh, India.
Authorship contribution statement
Shefali – Original draft writing, investigation. Shabnam Negi – Conception and design of the study. Sameer Makkar – Final Draft supervision. Sanjay Mittal – Provision of material. Ishan Garg – Procurement of data.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Acknowledgment
The authors would like to thank Dr. Ravneet Kaur (MDS, Public Health Dentistry) and Dr. Mohit Bansal (MDS, Public health Dentistry) for their assistance in statistical analysis and Dr. Akshun S. Gupta (MDS, Conservative Dentistry and Endodontics) for proofreading the article.
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