Home About us Editorial board Ahead of print Current issue Archives Submit article Instructions Subscribe Search Contacts Login 
  • Users Online: 617
  • Home
  • Print this page
  • Email this page

 Table of Contents  
Year : 2016  |  Volume : 28  |  Issue : 3  |  Page : 281-284

Dual cusped protostylid: Case report and clinical significance

1 Department of Oral Medicine and Radiology, Sarjug Dental College, Darbhanga, Bihar, India
2 Department of Oral Medicine and Radiology, Haldia Institute of Dental Sciences and Research, Haldia, West Bengal, India

Date of Submission26-Mar-2016
Date of Acceptance06-Dec-2016
Date of Web Publication13-Dec-2016

Correspondence Address:
Dr. Preeti Bhattacharya
2/3B, Basant Bahar, 947 - Jhilpar Road, Mahamayatala, Garia, Kolkata - 700 103, West Bengal
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-1363.195670

Rights and Permissions

Protostylids are superstructures on maxillary or mandibular molars, which have rarely been reported in literature, and the significance of their presence has also been underestimated. The dental practitioners may easily misdiagnose a tooth, with such conical tubercles as malformed tooth. Interestingly, this is neither a malformation nor an anomaly but rather an important morphological trait of an individual. Once in a while, one may come across such a distinct morphological trait without being able to diagnose. To the authors' best knowledge, only one similar case has been reported previously, and the second such case internationally. Bearing all such facts in mind, the authors attempt to educate the readers towards the existence of such a trait so that it can be identified and studied in larger numbers. Hence, it is the authors' endeavor to report an unusual case of dual cusped maxillary protostylid along with its clinical significance.

Keywords: Amelogenesis, molars, protostylid

How to cite this article:
Bhattacharya P, Sinha R. Dual cusped protostylid: Case report and clinical significance. J Indian Acad Oral Med Radiol 2016;28:281-4

How to cite this URL:
Bhattacharya P, Sinha R. Dual cusped protostylid: Case report and clinical significance. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2023 Feb 2];28:281-4. Available from: http://www.jiaomr.in/text.asp?2016/28/3/281/195670

   Introduction Top

Teeth develop as discrete organs in the oral cavity due to epithelial and mesenchymal tissue interactions and have been divided into the regions of incisor, canine, premolar, and molar tooth types from anterior to the posterior for the sake of simplification. The shape of molar teeth shows significant variations. The exact etiology of shape deviations is largely unknown, but still various studies suggest overactivity of the dental lamina. It is now believed that PAX and MSX genes are responsible for the abnormal shape of the teeth.[1] The existence of protostylid was first introduced by Late Prof. Bolk in the year 1916, and in 1945 Dahlberg referred to this structure as “parastyle” when evident on maxillary molars and “protostylid” when present in mandibular molars.[2] Protostylid may be encountered on the buccal surface of the mesiobuccal cusp of deciduous and permanent maxillary molars and rarely on the distobuccal cusp of the maxillary molars. Moreover, dual cusps existence is particularly uncommon.[3] We report here an extremely interesting and rare case of the presence of dual cusped protostylid on the maxillary molar with emphasis on clinical implications and their significance.

   Case Report Top

A 21-year-old male patient reported to our department for routine dental checkup. His medical, dental, and family history was noncontributory. On intraoral clinical examination, two well-developed lobulated tubercles were found on the buccal surface of tooth 17 [Figure 1] and [Figure 2]. These conical projections were asymmetrical in shape and the distal tubercle was slightly larger than the mesial one and both of them were more or less expressed on the mesiobuccal cusp. The distal and mesial tubercles measured roughly 8 × 5 mm and 6 × 4 mm, respectively [Figure 3]. The surface of the tubercles appeared smooth without any evidence of dental caries. Extrinsic staining of the tubercles and grooves was noted. Gingival recession was observed on the buccal surface, which was particularly more evident with respect to the distal tubercle.
Figure 1: Occlusal aspect of 17 showing dual cusped protostylid

Click here to view
Figure 2: Buccal aspect of 17 showing dual cusped protostylid

Click here to view
Figure 3: Mesial and distal conical projections arising from the mesiobuccal cusp of 17

Click here to view

A provisional diagnosis of dual cusped protostylid was made and an intraoral periapical radiograph (IOPAR) was taken. Though IOPAR has limited advantage in this case, it was taken to rule out any periapical changes secondary to an undiagnosed incipient caries. The radiograph showed slightly increased radiopacity in the region of protostylid without any evidence of bone loss or periapical changes [Figure 4]. The final diagnosis of dual cusped protostylid was confirmed and the patient was referred for oral prophylaxis without any further delay.
Figure 4: IOPAR of 16,17, and 18 showing increased radiopacity with respect to crown of 17

Click here to view

   Discussion Top

Bolk described protostylid as any stylar anomalous cusp, supernumerary eminence, or inclusion on the buccal surfaces of maxillary and mandibular posterior teeth. Very few case reports in literature describe the occurrence of protostylid in human dentition. The existence of protostylid in maxillary second molars is extremely rare ranging from 0.4% to 2.8% in various populations.[3] These structures are reported to be sporadic among Africans and Europeans, whereas more common in native Americans. The formation of cuspal structure was not noted among Negroes, Filipinos, and Hawaiians, whereas a higher occurrence in both deciduous and permanent molars of southwestern Indians has been reported.[4] The presence or absence of these structures can provide important clues to the ethnic or racial background of the individuals, and they should not be classified as anomalous structure because they are normal morphological features of the dentition.[5] Various molecular studies have suggested that the formation of occlusal table of the posterior teeth is controlled by primary enamel knot, whereas the cusps formation is regulated by secondary enamel knots during amelogenesis.[6]

The presence of protostylid on teeth can vary from a groove of variable size to well-formed tubercle. The groove type protostylid or surface irregularity is more common than the other type. The floor of such a groove shows one or more pits of various sizes, which lie between a large protoconid and a nearly negligible protostylid consisting of dentine core only. This can be regarded as the initial stage of cusp formation due to presence of amelodentinal junction beneath it. The presence of calcoglobules at the base of these pits suggests morphological and histological similarity with occlusal fissures.[6] The mineralized component in pits walls shows presence of aprismatic enamel and stunted prisms and thus indicate a severe disturbance in the function of ameloblasts.[7]

Clinical implications

The presence of protostylid can be germane as various clinical problems can arise and might influence the course and outcome of treatment modalities.

  • If there is presence of an additional root canal within the protostylid then endodontic therapy should be performed with special care. The orientation of pulp of tubercle with the pulp chamber of the tooth should be determined before commencing any treatment and then both should be treated at the same time [8]
  • These additional structures are potent sites for plaque retention as maintenance of oral hygiene in these areas is difficult and can lead to dental caries, gingivitis, and localized periodontitis. Gingival recession was evident in our case also
  • Vertical bone loss may result if the grooves separating the tubercles from the teeth extend onto the root surfaces, which provide potent pathway to periodontal microbes
  • During orthodontic treatment, protostylid can interfere with adaptation of the molar bands. Often it is necessary to remove the projecting structure by ameloplasty, but the authors would suggest that all efforts should be made to retain the unique characteristic of the dentition
  • The presence of tubercles with pulpal tissue can be problematic during tooth preparation for prosthetic crown, and thus may necessitate endodontic treatment prior to any other procedure
  • From the oral medicine specialist viewpoint, utmost care should be implied to not to misdiagnose protostylid pits as enamel hypoplasia. The two can be discriminated by the nature of the underlying amelodentinal junction microscopically. The elevation to form a cusp, presence of surface aprismatic enamel, and stunted enamel prisms indicate protostylid.[9] Moreover, buccally projected protostylid may be a predisposing factor for traumatic cheek bites
  • These superstructures are either extremely rare or underreported, however, they can be valuable clues to racial orientation and add unique identification to an individual's dentition. Thus, the reporting and preservation of these structures can be important from the perspective of forensic odontology.

   Conclusion Top

Human teeth may show large variations in their morphology, which may vary from absence of cusp/s to presence of supernumerary cusp/s or roots. A protostylid is a similar supernumerary cusp, which is most commonly located on the mesiobuccal surface of the molars. Because the dental faculty is not exposed to the presence and significance of protostylid, the diagnosis of such a trait can easily be missed or misdiagnosed. This sporadic unique morphological feature may be useful in person identification in mass disasters or post crime scenes. Hence, utmost care should be employed to preserve the unique identification of an individual's dentition.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Butler PM. Ontogenetic aspects of dental evolution. Int J Dev Biol 1995;39:2.  Back to cited text no. 1
Ramachandra JA, Vora MS, Nihal NK, Thimmegowda U. Bilateral paramolar tubercles on the distobuccal surfaces of mandibular primary first molars: A rare occurrence. J Clin Diagn Res 2015;9:ZJ05.  Back to cited text no. 2
Kustaloglu OA. Paramolar structures of the upper dentition. J Dent Res 1962;41:75-83.  Back to cited text no. 3
Dahlberg AA. The evolutionary significance of the protostylid. Am J Phys Anthropol 1950;8:15-26.  Back to cited text no. 4
Nirmala SVSG, Gaddam KR, Vimaladevi P, Nuvvula S. Protostylid: A case series. Contemp Clin Dent 2013;4:349-52.  Back to cited text no. 5
[PUBMED]  Medknow Journal  
Thesleff I. Developmental biology and building a tooth. Quintessence Int 2003;34:613-20.  Back to cited text no. 6
Gaspersic D. Morphology of the most common form of protostylid on human lower molars. J Anat 1993;182:429-31.  Back to cited text no. 7
Nayak G, Shetty S, Singh I. Paramolar tubercle: A diversity in canal configuration identified with the aid of spiral computed tomography. Eur J Dent 2013;7:139-44.  Back to cited text no. 8
Tummers M, Thesleff I. The importance of signal pathway modulation in all aspects of tooth development. J Exp Zool B Mol Dev Evol 2009;312B: 309-19.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

   Abstract Introduction Case Report Discussion Conclusion Article Figures
  In this article

 Article Access Statistics
    PDF Downloaded226    
    Comments [Add]    

Recommend this journal