Maxillary unilateral parastyle: An Orthodontist’s Conundrum

The developmental anomalies can be in the form of mild alteration in shape of crown or root such as development of an extra supernumerary cusp in both primary and permanent dentition. Such developmental disturbances are rare in permanent dentition. Parastyle is one common form of accessory cusp of permanent mandibular molar. Though its presence is not an alarming condition, it is of great importance in medicolegal cases. We herein report a case of parastyle on permanent maxillary second molar, its development, classi ﬁ cation, histopathological appearance and its clinical implications.


Introduction
Development of dentition is a cascade of events that take place due to the interaction of ectodermally derived oral epithelium and neural crest derived mesenchyme. Interference in any one of these events in tooth development leads to a developmental disturbance. The developmental anomalies can be in the form of mild alteration in shape of crown or root such as development of an extra supernumerary cusp in both primary and permanent dentition. The dental trait that are rarely encountered includes parastyle, protostylid, entoconulid and metaconulid which are anatomical variations [1].
Parastyle is a morphological anomaly and presents with a supernumerary cusp, usually found in association with buccal surface of maxillary molars on their mesial aspect. Parastyle is also known as paramolar tubercle or Bolk's cusp in literature [2]. The presence of parastyle may not always be alarming but can also cause complications such as dental caries, sensitivity in the cusp with pulp extension due to attrition and can also cause devitalisation due to fracture. These morphological alterations are of great signifi cance in medicolegal cases [3].
The purpose of this case report is to focus on uncommon dental trait, parastyle in permanent dentition and its management.

Discussion
Accessory or supernumerary cusp is an extra cusp associated with the tooth that is occasionally seen clinically.
Among primates, certain accessory cusp has peculiar and limited distribution. One among the peculiar and rare anomaly is the parastyle, derived from the anterior portion of buccal cingulum of the molars [4].
First description on Parastyle was given by Dahlberg who reported an extra cusp on primary maxillary molar on Eskimo skull in 1950 [5]. Parastyle was then termed as "upper paramolar complex" by Kustaloghi [6]. Paramolar tubercle/ parastyle vary with shape and size ranging from a small eminence on the outer surface to a well-developed lobulated cusp. Pulp may or may not always be present in the tubercle.
Study has reported that the presence of parastyle is more common in Indian population [7].   so that it will avoid possibility of pulpal exposure and helps in reparative dentine formation. Patient will be advised to use desensitizing tooth paste during this time period. Stepwise or gradual reduction of accessory cusp should be followed as it preserves the pulp vitality and averts the risk of pulp exposure and discomfort associated with deep dentinal preparation.

Classifi cation
The grinding of the cusp should be carried out along the side of the cusp and not the tip of the cusp so as not to damage the odontoblasts. The special care during reduction of cusp is taken because most of the odontoblasts lie along the length of the cusp. These odontoblasts promote deposition of reparative dentin over a period of few weeks [15].
1. Fissure sealants or glass-ionomer cement to seal associated grooves as prophylactic measure.
2. Complete reduction of cusp followed by calcium hydroxide pulpotomy for an immature tooth if pulpal exposure is encountered.
3. Once the cusp is fl attened completely, it should be followed by root canal treatment to avoid non vitality of pulp in the future.

Conclusion
Parastyle, though very rare to be presented, needs proper diagnosis and treatment if the orthodontic treatment is planned to be carried out. The thickness of the paramolar tubercle will jeoparadise the alignment of the that particular tooth within the arch because of the tip, torque and in-out variations inbuilt in the preadjusted edgewise appliance of present generation.