Journal of Indian Academy of Oral Medicine and Radiology

: 2016  |  Volume : 28  |  Issue : 1  |  Page : 57--60

Protostylid: As never reported before! A unique case with variation

Vela D Desai1, Harsha Sadnani1, Sunil MV Kumar2, Prerna Pratik3,  
1 Department of Oral Medicine and Radiology, Jaipur Dental College, Jaipur, Rajasthan, India
2 Department of Prosthodontics, Jaipur Dental College, Jaipur, Rajasthan, India
3 Private Practice, Patna, Bihar, India

Correspondence Address:
Vela D Desai
B: 406, Trimurthy Apartments, Opposite BSNL Telecom Colony, Malviya Nagar, Jaipur - 302 017, Rajasthan


Human jaw and teeth display a high degree of morphological individuality as they represent personal, familial, and population characteristics and one among them are cuspal variations. A protostylid is a supernumerary or accessory cusp located on the mesiobuccal surface of the mandibular molars that seldom pose problems. A forensic odontologist may find significant interest in its classification and identification among victims of mass causalties and bite marks on living and nonliving objects. The authors here are reporting a case of protostylid with a unique presentation which, to best of our knowledge is not reported so far.

How to cite this article:
Desai VD, Sadnani H, Kumar SM, Pratik P. Protostylid: As never reported before! A unique case with variation.J Indian Acad Oral Med Radiol 2016;28:57-60

How to cite this URL:
Desai VD, Sadnani H, Kumar SM, Pratik P. Protostylid: As never reported before! A unique case with variation. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2020 Jul 12 ];28:57-60
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Teeth of human dentition show wide variation and present with differences in their morphological features in both deciduous as well as permanent dentition. Such changes may be found on the crown either in the form of anomalous cusps or an increase in a number of roots.[1] “Paramolar Tubercle” is the term used for any stylar anomalous cusp, supernumerary inclusion, or eminence occurring on the buccal surface of both upper and lower premolar and molars.[2] In 1945, Dahlberg introduced a specific paleontological nomenclature referring to this structure as parastyle when present in the upper molars and as protostylid when present in the lower molars.[3] De Jonge-Cohen termed them as “Mesiobuccal edge prominencies.”[4] The authors present here, a case of varied presentation of protostylid along with extra cusp bilaterally on the third molars confirmed with cone-beam computed tomography (CBCT) imaging which is not reported in literature till date.

 Case Report

A 21-year-old male patient reported to the dental OPD of the Department of Oral Medicine and Radiology, with a chief complaint of dirty teeth and bleeding gums for the last 7 months. Medical and family history were noncontributory. There was no history of consanguineous marriage in the family. General physical examination was normal. On thorough intraoral examination, a unique combination of six cusped 48 with a premolar-shaped extra cusp was evident. The tooth-like structure was attached to the mesiobuccal cusp of 48 measuring approximately 4 mm mesiodistally and 5 mm buccolingually. It had distinct two cusps resembling a small premolar [Figure 1]. The cusp attached to the buccal surface of the molar was larger and at the level of the occlusal plane, and the one towards the buccal mucosa appeared to be smaller and approximately 3 mm below the occlusal plane. There were rudimentary extra cusps, visible on the disto-occlusal surface, in 48 [Figure 2]. Continuous trauma from this tooth resulted in frictional keratosis on the retromolar trigone area. On the opposite side of the arch also, triangular-shaped extra cusp was noticed on the distal aspect of 38, resulting in friction on the left retromolar trigone [Figure 3] and [Figure 4]. As the patient was young and educated, he maintained a good oral hygiene. There were no features of periodontal breakdown, catch, or discoloration of the tooth. A provisional diagnosis of protostylid and accessory cusp with respect to 48 and 38 along with frictional keratosis on the right and left retromolar region was made. A differential diagnosis of the supernumerary tooth was also considered. Oral hygiene was fair with only minimal amount of calculus and stains leading to chronic generalized gingivitis. After the patient's informed written consent, clinical photographs and study model were indicated. Radiovisiography revealed an inverted dense “U” shaped radiopacity without distinct root [Figure 5]. CBCT was indicated to delineate the structure, roots, and extension of the cusp. CBCT images revealed that the protostylid was attached only to the mesiobuccal aspect of the tooth and not extending beyond the cervico-enamel junction [Figure 6],[Figure 7],[Figure 8],[Figure 9]. Oral prophylaxis and topical fluoride application were performed. Education regarding meticulous oral hygiene maintenance was advised, and genetic counseling was done. Coronoplasty was advocated for lower third molars and was periodically recalled.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}{Figure 7}{Figure 8}{Figure 9}


Elevations or a mold on the crown portion of the tooth which make up a divisional part of the occlusal surface is denoted as a cusp. Supernumerary or accessory cusps are the extra number of cusps that occur on the surface of the tooth.[1] Accessory cusps can occur both as dental anomalies (dens evaginatus) or as normal anatomical variations (protostylid, parastyle, and so on). These morphological variants manifest in low frequencies in the human populations and represent racial and regional variations [2],[5],[6] too. Many theories have been proposed to explain the origin of multicusp mammalian teeth: Concrescence theory, differentiation theory, and tritubercular theory.[7] The etiology of extra cusp formation or abnormal shape is multifactorial. However, it is said that these features are probably a result of overactivity of the dental lamina, but presently, it is believed that PAX and MSX genes are responsible for the abnormal shape of the teeth.[8],[9]

Paramolar tubercles provide insight into dental evolution and development. Hanihara [10] in 1961 proposed the classification for the same. Since then various studies and case reports are published in literature pertaining to the prevalence, clinical presentation, regional, and racial variations. To the best of our knowledge, the cases presented in English literature have only single cone-shaped cusp. The triangular prominences have their base below the gingival margin with their apex below the occlusal plane. In this article, the protostylid had two distinct cusps resembling a small premolar (microdont, supernumerary) which is seldom-documented.

As this is a common site for supernumerary tooth, which also can vary in size and shape and mostly present with a root either short or fully formed, a diagnostic dilemma arose. Extra tooth was ruled out by the absence of roots on a radiovisiography image and confirmed by CBCT. Axial scan images of CBCT (cervical, middle, and apical third) of the roots of the tooth with protostylid demonstrated the absence of root. This case needs documentation as a variant of protostylid and if so, classification needs to be revised.

Another presentation of this case was extra cusp in both the lower third molars. However, with the fact that the third molar is in a phase of evolution, its presence, absence, shape, and size cannot be standardized. Noteworthy, in this case, was the presence of frictional keratosis bilaterally in the retromolar region which could be added as one of the clinical implications. These morphological variations can lead to various clinical implications:[11]

Difficulty in placement of stainless steel crownsPossibility of failure of pulpectomy due to missed canal in primary teeth [8]Interferance with cementation of brackets, banding, and proper alignment of wires during orthodontic treatmentIncreased chances of food lodgment leading to plaque accumulation causing localized gingivitis, periodontitis, and cariesDifficulty in root canal treatment and possibility of failure• Sharp extra cusps may result in frictional keratosis (as in this case report).

In this case study, the patient maintained a relatively good oral hygiene in spite of the extra cusp. However, he was educated and advised regular monitoring of the embracer areas for early detection.


The authors present here a unique morphological variation rarely seen in mandibular third molars. Patients with additional tooth projections should be subjected to routine and periodic dental evaluation which includes monitoring of the degree of attrition, periodontal status, and tooth vitality. Early diagnosis and management are important if complications are to be avoided. The dental polymorphisms described in this paper are some of the rarest and unique paleontological forms of the human dentition.

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Conflicts of interest

There are no conflicts of interest.


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