# Root Dilaceration and Dentigerous Cyst--A Cause-Effect Relationship?--\"Case-Series Study\"
## 4 Discussion
Accordingly, all the patients included in the study underwent panoramic X-rays and CBCTs. In accordance with other studies, in the present case series study, DL had no sex prediclection, occurred anywhere along the length of the root, and affected any teeth [36]. A recent study showed that root DLs in incisors, canines, and premolars are most common in the apical third of the roots. DL within the middle third of the root is more frequent in molars, whereas DL within the coronal third of the root is most commonly seen in third molars [16]. Crown DLs are less common than root DLs, and they usually occur in maxillary permanent incisors because of their proximity to primary incisors [23; 24]. Our findings have shown that in cases where the DL occurred in the cyst-associated tooth, the middle or coronal third of the root is affected (cases 3 and 5). In one of five cases, bilateral DL occurs in mandibular first molars. Without a consensus among researchers, the etiology of DL is not fully understood, thus many etiologic factors are considered, such as trauma, scar formation, a developmental anomaly of the primary tooth germ, facial clefting, advanced root canal infections, ectopic development of the tooth germ, lack of space, and the effect of anatomic structures (cortical bone of the maxillary sinus, mandibular canal, or nasal fossa), which might deflect the epithelial diaphragm, presence of an adjacent cyst, tumor, or odontogenic hamartoma, mechanical interference with the eruption from an ankylosed primary tooth that does not resorb, tooth transplantation, extraction of primary teeth, and genetic factors [7; 12; 15; 16; 17; 18; 58; 59; 60; 61; 62; 63; 64; 65; 66; 67]. The involvement of the genetic factor can also be enhanced by the fact that the identification of the master genes, from the gene regulatory system, responsible for induction and tooth regeneration should be taken into consideration to obtain an appropriate architectural design of a bioengineered tooth [68]. There is also another hypothesis regarding DL etiology affecting the middle and apical part of the root-tooth root dilacerations due to the bone gradients of plasticity present in alveolar bone, which could be affected by the rate of eruption, jaw rotation, length of the root, length of the eruption path, delayed eruption, transverse uprighting of molar teeth during eruption, and root resorption [45; 55]. The present study aimed to find if the presence of DC, mentioned in the literature as an etiologic factor, could be the single cause of tooth DL. The results show that in all five cases, the presence of a DC is associated with root DLs either in the adjacent teeth or in the cyst-associated tooth. Consequently, DC could be considered the cause of DL. In all of these clinical situations, there was a lack of space in the affected area caused by another etiologic factor, such as a supernumerary tooth, impaction of an adjacent tooth, or a delayed eruption. Bone density should also be taken into consideration as another etiologic factor (cases 3 and 4), together with jaw rotation (5), closed proximity of different anatomical structures (sinus-case 1; nasal cavity-case2,5) and length of the eruption path (case 1). At least one of the following dental anomalies was noted in every case: supernumerary tooth, transposition, impaction, congenitally missing tooth, delayed eruption, and in cases 1, 3 and 4, root DLs also affected other teeth away from the area of the DC-associated tooth. Thus, another etiologic factor could be the genetic origin of DL. While considering the limitations of the present case series study, it could be stated that except for trauma, the etiology of DC is multifactorial, and associated with dental anomaly patterns of a genetic origin. DC could cause tooth DL in association with other local or genetic factors. As a dental anomaly pattern, early treatment for DLs is important to reduce the complexity of the treatment and save the teeth. Sometimes classic DC coexists with other serious conditions, such as keratocyst or ameloblastoma.