Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
Indian Journal of Dental Research   Login   |  Users online:

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         


Table of Contents   
Year : 2020  |  Volume : 31  |  Issue : 4  |  Page : 656-661
Palatoradicular groove: The hidden predator and etiological factor – Advanced proposed classification and literature review

Department of Dental Surgery, M L N Medical College, Prayagraj, Uttar Pradesh, India

Click here for correspondence address and email

Date of Submission23-Nov-2017
Date of Acceptance27-May-2019
Date of Web Publication16-Oct-2020


Palatoradicular grooves are usually found on the palatal or lateral roots of maxillary central and lateral incisors. Since clinical identification of these grooves are inaccessible and arduous in routine oral hygiene practices and are susceptible alcoves for microorganism habituation and plaque accumulation, it may result in acute to severe periodontitis and, if untreated, periapical pathosis also. This paper discusses about a female patient who reported pus discharge in left upper lateral incisor. Based on history, clinical examination and IOPA (intra-oral periapical radiograph), a deep pocket of about 10–14 mm was noticed in the left upper lateral incisor. A timely investigation was made and was treated surgically with advanced modified procedures which include odontoplasty and restoration of the defect with Platelet Rich Fibrin. After follow up of 6 months, the patient reported no signs of disease progression, had good oral hygiene and the tooth remained to be vital.

Keywords: Calcium silicate cement, lateral incisor, palatoradicular groove, periodontitis, platelet rich fibrin

How to cite this article:
Yadav N, Kumar A. Palatoradicular groove: The hidden predator and etiological factor – Advanced proposed classification and literature review. Indian J Dent Res 2020;31:656-61

How to cite this URL:
Yadav N, Kumar A. Palatoradicular groove: The hidden predator and etiological factor – Advanced proposed classification and literature review. Indian J Dent Res [serial online] 2020 [cited 2022 Aug 19];31:656-61. Available from:

   Introduction Top

Palatoradicular or Palatogingival groove was initially given by Black in the year 1908 described it as a developmental anomaly. Maxillary central incisors are most frequently involved teeth amongst all other teeth usually begins near central fossa crosses the cingulum and extends towards apical direction to reach the tooth apex. In most cases, the location and anatomy of these malformations are such that they promote adherence of plaque and render relatively easy involvement of the dental pulp contributing significantly towards the development of endodontic - periodontal lesions.[1]

   Case Report Top

A 31-year-old female patient reported to the Department with the chief complaint of purulent discharge on labial alveolar mucosa, accumulation of plaque and calculus, occasional mild sensitivity and swelling on palate and gums in the upper left front tooth (22) for the last two months. The clinical examination revealed localised swelling and an intraoral draining sinus pointing on the labial gingiva between the upper left lateral incisors. There was no history of trauma, caries, and discoloration of the tooth. Periodontal examination revealed a periodontal pocket of more than 12 mm deep on the palatal aspect and bleeding on probing present on the upper lateral incisor (22) along the groove with grade 2 mobility [Figure 1]. Intra-oral examination revealed the presence of plaque in relation to maxillary right lateral incisor that showed bleeding on probing. Based on radiographic interpretation and clinical examination, the presence of palatoradicular groove was diagnosed in the midpalatal region of 22 [Figure 2] and [Figure 3].
Figure 1: Pocket probing depth of 13 mm

Click here to view
Figure 2: The palatoradicular groove (PRG) was detected in relation to 12

Click here to view
Figure 3: IOPA showing horizontal bone loss on both mesial and distal aspect 12

Click here to view

   Treatment Top

The tooth showed immediate response upon vitality test and was therefore considered to be vital. The patient received a session of oral prophylaxis, including scaling and root planning, and proper oral hygiene instructions. On re-evaluation after a month of phase I therapy, the pocket was still persistent in 22 along with grade 2 mobility. Splinting was done from maxillary left central incisor to canine 21 to 23 and phase II therapy was planned for the patient, which included localised flap surgery and restoration of the PRG [Figure 4]. The surgical area was made aseptic with betadine and under local anaesthesia sulcular incisions and interdental incisions were made around 21, 22 and 23 and a full-thickness mucoperiosteal flap was elevated in relation to the buccal and palatal aspects of 21, 22 and 23 [Figure 5].
Figure 4: Splinting was done in relation to 11 to 13

Click here to view
Figure 5: Full thickness flap was elevated in relation to the buccal and palatal aspect of 11, 12 and 13

Click here to view

Upon surgical curettage of granulation tissue and irritants, the palatoradicular groove was visualised and was found extending till one third of the root length [Figure 6]. After instrumentation of root surface and adequate moisture control, it was decided to seal the PRG. Odontoplasty was done in the coronal aspect and the radicular portion of the groove was sealed with calcium silicate cement due to superior handling characteristic and excellent biocompatible [Figure 7] and the osseous defect was filled with PRF [Figure 8]. Then, the flap was positioned back and stabilised with simple interrupted sutures of 3-0 black silk [Figure 9]. After the surgery, the patient was prescribed amoxicillin 500 mg thrice daily for 5 days, paracetamol 500 mg thrice daily for 3 days and 0.2% CHX gluconate rinse mouthwash 2 times a day for 4 weeks. The suture was removed after a week and healing of the wound was uneventful [Figure 10]. Postoperative six months follow up showed considerable healing with reduction in probing depth to 6 mm, resolved facial sinus tract and revealed satisfactory gingival adaptation to the sealed groove as well as maintenance of periodontal health and vitality of the tooth [Figure 11] and [Figure 12]. Postoperative periapical radiograph was taken for follow up which reveals no evidence of periapical pathology in 22 and excellent bone filling of osseous defect [Figure 13]. No orthodontic treatment was required.
Figure 6: Palatoradicular groove was visualised and found extending till one third of root length

Click here to view
Figure 7: Odontoplasty was done and radicular portion of the groove was sealed with GIC

Click here to view
Figure 8: The osseous defect was filled with PRF

Click here to view
Figure 9: The flap was positioned back stabilised with simple interrupted sutures of 3-0 black silk

Click here to view
Figure 10: Suture removal was done after a week. Healing of the wound was uneventful

Click here to view
Figure 11: Postoperative six months follow up showing reduction in probing depth to 6mm and revealed

Click here to view
Figure 12: Six months postoperative follow up showed satisfactory gingival adaptation to the sealed groove

Click here to view
Figure 13: Post-op IOPA after 6 months

Click here to view

   Discussion Top

Kovacs (1971)[1] called this anomaly 'syndesmocorono -radicular tooth'. In a morphological analysis of these grooves, Ennes and Lara[2] suggested that the palatal groove could be the result of an alteration of genetic mechanisms, rather than an enamel organ folding.[3],[4] The groove made its first identity in dental anatomy text in 1917 and was later described by Zeisz Nuckolin (1949).[4] The first classification of invaginated teeth was published by 'Hallet' in year 1953[5] but the most commonly used classification is given by Oehlers in 1957[6] and he also describes the radicular form of invagination in year 1958 in an upper lateral incisor in a Chinese female.[6] In 1965, Prichard[7] explained this as a defect predisposed to the formation of periodontal pockets.[6] Later, Lee et al.[8] formulated the term 'groove' which was not used in dental literature until then, while presenting a case report concerning palatal grooves in maxillary laterals.[7],[8]

These hidden periodontal grooves and accumulation of supra and subgingival plaques can predispose to infect the pulp in a retrograde manner and result in necrosis of pulp and establishment of communication between pulp chamber (endodontics) and periodontium (periodontal) lesions through accessory canals.[9],[10] The challenges in treating the palatoradicular grooves make its diagnosis complex for oral health practitioners. This complexity can result in ineffective endoperio treatment attempts, because this groove can be exclusively periodontal or, if not, the treatment can be of little use without the removal of predisposing factors and treatment of the resulting endodontic or periodontal pathosis.[11],[12]

The radicular groove has been classified into three groups based on severity[11]

  • Type 1: Groove is limited to coronal third of root.
  • Type 2: Groove is extended beyond the coronal third of root but is shallow and pulp is not exposed.
  • Type 3: Groove is long, deep and extends beyond the coronal third of root and involves the root canal system involved.

After an examination of 3,168 extracted incisors, Kogon[12] reported the prevalence of the palatogingival groove to be 3.4% in central incisors and 5.6% in lateral incisors.[11] In the present case, it was present starting from the cingulum till the apical third of the root.

Dental anomalies are the problems, dysfunctions of oral tissues and developmental defects or deformities which are often unnoticed in diagnosis. The developmental anomalies that represent an infolding of the enamel organ and the epithelial sheath of Hertwig are known by various names such as the palatogingival grooves, radicular lingual grooves, palatal radicular grooves, radicular palatal grooves, distolingual grooves or radicular gingival grooves.[13],[14]

The maxillary lateral incisors are usually affected because of their embryological hazard of having its tooth germs or displacement of cemento-enamel junction between central incisor and canine. Diagnosis of the radicular lingual groove as the initiator of pathology is essential especially in the cases where a patient may present with pulpal involvement in teeth that have no relevant history or clinical finding or history of trauma 12, similar to the one present in the present case. Lee[8] reported a positive association between palatogingival groove and localised periodontitis. Clinically, grooved teeth have demonstrated significantly higher plaque, gingival and periodontal disease index scores than non-grooved incisors. Accessory canals of maxillary lateral incisors connecting to the pulp chamber in the depth of the grooves which may lead to bacterial ingress to the pulp space have been reported in literatures.[12]

The exact aetiology of this defect is not fully understood. Some clinicians believe that the radicular groove represents the mildest form of dens invaginatus and, therefore, the pathogenic mechanism is relatively common. This means that there is minimal in folding of the enamel organ and epithelial sheath of Hertwig during odontogenesis.[13],[14]

Aetiology is yet to be proved but few past literatures suggest as follows[15],[16]

  • Analogous to pathogenesis of dens invaginatus
  • Slight folding of enamel organ and HERS during odontogenesis
  • Appropriate depth for accumulation of plaque and habitat of microorganism.

Maxillary lateral incisors are among the few tooth of all 32 teeth in dentition which exhibit anatomic abnormalities and diverse morphologies such as[17],[18]

  • Peg Shaped
  • Gemination
  • Dens Invaginatus
  • Eagel's Talon
  • Fusion
  • Accessory root
  • Palatogingival Groove.

Various modalities have been implicated for the treatment of the palatogingival groove ranging from odontoplasty and saucerisation to filling the groove with restorative materials such as glass ionomer cement, composite and amalgam (Brunsvold 1985,[17] Friedman and Goultschin 1988).[18] Glass ionomer cement has been used in this case as it has an antibacterial effect, chemical adhesion to the tooth structure and good sealing ability (Maldonado et al. 1978,[19] Vermeersch et al. 2005[20]). Clinical and histological studies have shown that there is an epithelial and connective tissue adherence to the glass ionomer cement during the healing process.[16] The intra-osseous defect, if present, can be grafted with bone fillers. Since there was an advanced circumferential bony defect, platelet-rich fibrin was placed to promote bone regeneration. In the present case, clinical success might be attributed to elimination of the local factor for supragingival and subgingival plaque accumulation by filling the groove with a restorative material and treating the osseous defect with PRF.[21],[22],[23]

Treatment advanced modified modalities proposed for such hidden predators are as follows-

To treat such type of radicular grooves, numerous steps required. Therefore, we have combined all the steps under one advanced modalities plan:

  • Under Periodontal Treatment
  • Under Endodontic Treatment
  • Surgical Technique
  • Orthodontic Treatment

  1. Steps in Periodontal Surgery-

    • Scaling and root planning
    • Surgical curettage of periodontal tissue (granulation tissue and irritants) closed flap
    • ” OR”
    • In open flap technique, gingivectomy and surgical exposure of flap (apically positioned)

  2. Steps in Endodontic Treatment Plan

    • Odontoplasty if required
    • Restore or seal the radicular groove with biocompatible material
    • Saucerisation of groove with or without root canal treatment (if endodontic lesion is present)

  3. Step in Surgical Technique

    • In surgical technique, flattening of groove with or without application of GTR (guided tissue regeneration) technique

  4. Orthodontic Treatment

    • Orthodontic extrusion of teeth if required

In a case report by Zahra Alizadeh Tabari et al.[24] in the year 2016, due to the presence of deep periodontal pocket and severe attachment loss, the surgical procedure was performed. After flattering and odontoplasty of the groove, the anatomy of the root was favourable. Hence, restorative materials were not used to restore the groove. They also reported a case of developmental groove and supernumerary teeth in which no restorative material was used after completion of the procedure.[25],[26]

The presence of radicular lingual grooves does not always indicate the development of pathology. In most cases, the epithelial attachment remains intact across the groove. Once the attachment is breached, a self-containing pocket forms along the length of the groove or by gingival irritation secondary to microbial plaque retention.[27],[28],[29],[30]

   Conclusion Top

The palatoradicular groove is a rare but potentially problematic area, which should be evaluated and treated accordingly. The groove can lead to focal loss of periodontal attachment which may extend to root apex and result in hopeless prognosis of tooth retention, which are difficult to deal with and, therefore, attention has been brought to its presence and clinical significance. Endodontic or periodontic lesions can be preliminary in the combined lesion, which is difficult to differentiate in clinical practice. Therefore, most combined lesions may successfully be treated with an interdisciplinary approach.

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

Kovacs J. A systematic description of dental roots. Dahlberg AA. Dental morphology and Evolution. Chicago, University of Chicago Press; 1971. p. 211-56.  Back to cited text no. 1
Ennes JP, Lara VS. Comparative morphological analysis of the root developmental groove with the palato-gingival groove. Oral Dis 2004;10:378-82.  Back to cited text no. 2
Attam K, Tiwary R, Talwar S, Lamba AK. Palatogingival groove: Endodontic-periodontal management--case report. J Endod 2010;36:1717-20.  Back to cited text no. 3
Zeisz RC, Nuckolin J. Dental Anatomy. St. Louis, CV Mosby Co.; 1949. p. 65.  Back to cited text no. 4
Nalawade TM, Pateel D, Mallikarjuna R, Gunjal S. Dens invaginatus type II associated with an impacted mesiodens: A 3-year follow-up. BMJ Case Rep 2013;2013:bcr2013200211.  Back to cited text no. 5
Oehlers FA. Dens invaginatus (dilated composite odontome). I. Variations of the invagination process and associated anterior crown forms. Oral Surg Oral Med Oral Pathol 1957;2013:1204-18.  Back to cited text no. 6
Prichard JS. Advanced Periodontal Therapy. Philadelphia, WB Saunders Co.; 1965.  Back to cited text no. 7
Lee KW, Lee EC, Poon KY. Palato-gingival grooves in maxillary incisors. A possible predisposing factor to localised periodontal disease. Br Dent J 1968;124:14-8.  Back to cited text no. 8
Ballal NV, Jothi V, Bhat KS, Bhat KM. Salvaging a tooth with a deep palatogingival groove: An endo-perio treatment a case report. Int Endo J 2007;40:808-17.  Back to cited text no. 9
Kishan KV, Hegde V, Ponnappa KC, Girish TN, Ponappa MC. Management of palato radicular groove in a maxillary lateral incisor. J Nat Sci Biol Med 2014;5:178-81.  Back to cited text no. 10
Schafer E, Cankay R, Ott K. Malformations in maxillary incisors: Case report of radicular palatal groove. Endod Dent Traumatol 2000;16:132-7.  Back to cited text no. 11
Kogon SL. The prevalence, location and conformation of palato-radicular grooves in maxillary incisors. J Periodontol 1986;57:231-4.  Back to cited text no. 12
Arun A, Bhandi S, Subhash TS. Palato- gingival groove (PGG)-An enigma. Int J Contemp Dent 2010;1:4-8.  Back to cited text no. 13
Gu Y-C. A micro-computed tomographic analysis of maxillary lateral incisors with radicular grooves. J Endod 2011;37:789-92.  Back to cited text no. 14
Bhatsange A, Japatti S, Attur K. Palatogingival groove: Management of an innocuous culprit of a Perio-endo Lesion. Peoples J Sci Res 2012;5:43-6.  Back to cited text no. 15
Lara VS, Consolaro A, Bruce RS. Macroscopic and microscopic analysis of the palato-gingival groove. J Endod 2000;26:345-50.  Back to cited text no. 16
Brunsvold MA. Amalgam restoration of palatogingival groove. Gen Dent 1985;33:244-6.  Back to cited text no. 17
Friedman S, Goultschin J. The radicular palatal groove- a therapeutic modality. Endod Dent Traumatol 1988;4:282-6.  Back to cited text no. 18
Maldonado A, Swartz ML, Phillips RW. An in vitro study of certain properties of glass-ionomer cement. J Am Dent Assoc 1978;96:785-91.  Back to cited text no. 19
Vermeersch G, Leloup G, Delmee M. Antibacterial activity of glass-ionomer cement, compomers and resin composites: A relationship between acidity and material setting phase. J Oral Rehabil 2005;32:368-74.  Back to cited text no. 20
Withers JA, Brunsvold MA, Killoy WJ, Rahe AJ. The relationship of palato-gingival grooves to localized periodontal disease. J Periodontol 1981;52:41-4.  Back to cited text no. 21
August DS. The radicular lingual groove: An overlooked differential diagnosis. J Am Dent Assoc 1978;96:1037-9.  Back to cited text no. 22
Tabari ZA, Homayouni H, Pourseyediyan T, Arvin A, Eiland D, Majd NM. Treatment of a developmental groove and supernumerary root using guided tissue regeneration technique. Case Rep Dent 2016;2016:2738569.  Back to cited text no. 23
Gao ZH, Shi J, Wang Y, Gu F. Scanning electron microscope investigation of maxillary lateral incisor with a radicular lingual groove. Oral Surg Oral Med Oral Pathol 1989;68:462-6.  Back to cited text no. 24
Johns DA, Shivashankar VY, Shobha K, Johns M. An innovative approach in the management of palatogingival groove using Biodentine™ and platelet-rich fibrin membrane. J Conserv Dent 2014;17:75-9.  Back to cited text no. 25
[PUBMED]  [Full text]  
Pawar AM, Kokate SR, Shah RA. Management of a large periapical lesion using Biodentine(™) as retrograde restoration with eighteen months evident follow up. J Conserv Dent 2013;16:573-5.  Back to cited text no. 26
[PUBMED]  [Full text]  
Dragoo MR. Resin ionomer and hybrid ionomer cements: Part II. Human clinical and histologic wound healing responses in specific periodontal lesions. Int J Periodontics Rest Dent1997;17:75-87.  Back to cited text no. 27
Kerezoudis NP, Siskos GJ, Tsatsas V. Bilateral buccal radicular groove in maxillary incisors: Case report. Int Endod J 2003;36:898-906.  Back to cited text no. 28
Zucchelli G, Mele M, Checchi L. The papilla amplification flap for the treatment of a localized periodontal defect associated with a palatal groove. J Periodontol 2006;77:1788-96.  Back to cited text no. 29
Kim H-J, Choi Y, Yu M-K, Lee K-W, Min K-S. Recognition and management of palatogingival groove for tooth survival: A literature review. Restor Dent Endod 2017;42:77-86.  Back to cited text no. 30

Correspondence Address:
Dr. Nirma Yadav
Department of Dental Surgery, Moti Lal Nehru Medical College, Prayagraj, Uttar Pradesh
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_679_17

Rights and Permissions


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13]


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

   Case Report
    Article Figures

 Article Access Statistics
    PDF Downloaded75    
    Comments [Add]    

Recommend this journal