| Abstract|| |
Maxillary incisors are very susceptible to developmental anomalies that can lead to periodontal and/or endodontic problems. One such developmental anomaly is the palatal groove which is often associated with incorrect diagnosis, and subsequent treatment failure. This case report describes the use of spiral CT (Computed Tomography) scan to not only to accurately diagnose the groove on the maxillary right lateral incisor but also to confirm the depth and the relation of the groove to the pulp cavity. The management included a combination of endodontic therapy and periodontal regenerative techniques. Root canal therapy was performed followed by flap reflection, removal of granulation tissue and odontoplasty of the groove. Bone graft was placed followed by a resorbable barrier for guided tissue regeneration. Use of bone graft and a resorbable barrier in the treatment of palatal groove showed an improvement in clinical attachment, reduced probing depth and deposition of bone in the osseous defect.
Keywords: Palatal groove, Spiral-CT, Bone graft, Guided Tissue Regeneration.
|How to cite this article:|
Rachana D, Nadig P, Nadig G. The palatal groove: Application of computed tomography in its detection - a case report. J Conserv Dent 2007;10:83-8
|How to cite this URL:|
Rachana D, Nadig P, Nadig G. The palatal groove: Application of computed tomography in its detection - a case report. J Conserv Dent [serial online] 2007 [cited 2019 Jul 23];10:83-8. Available from: http://www.jcd.org.in/text.asp?2007/10/3/83/42266
| Introduction|| |
Morphological defects in the dental structure such as palatal groove can be predisposing factors for the onset of inflammatory processes in the periodontal and/or pulp tissues. These defects predominantly affect the maxillary incisors  .
In 1965, Prichard described this anomaly as a groove located on the lingual surface of the maxillary lateral incisors. In 1968, Lee, Lee and Poon named this anomaly, the palato-gingival groove. The anomaly has a variety of names radicular lingual groove,  palato-radicular groove , , radicular groove  . Occasionally, grooves can also be found on the facial aspect of the root which is termed as the facial-radicular groove , . This anomaly may be unilateral or bilateral, in which two grooves can occur on a single tooth, one on the facial surface and the other on the palatal surface  .
Various studies have reported that the palatal groove is seen in 2.8 % to 8.5 % of the cases, the most prevalent being in the maxillary lateral incisors  .
The palatal groove has a funnel-like shape and typically begins at the level of the cingulum extending to various lengths along the root , .
They are quite variable not only in their depth, but also the distance and direction traversed down the root. Mild ones terminate at the cemento-enamel junction, whereas the moderate grooves continue apically along the root surface. The most complex forms are deeply invaginated defects that separate an accessory root from the main root trunk  .
Lee and colleagues speculated that the palatal groove represents an infolding of the enamel organ and Hertwig's epithelial root sheath. According to some authors, the palatal groove is embryologically related to dens invaginatus, except that the infolding of the enamel epithelium is less extensive and creates an external defect adjacent to the gingival crevice.
Atkinson reported that the predominance of the palatal groove in the maxillary lateral incisors is explained by the reason that mineralization of the crown of the maxillary lateral incisor starts later, compared with others, making this germ highly susceptible to folding.
Ennes and Lara suggested that the palatal groove could be the result of an alteration of genetic mechanisms, rather than a dental germ folding.
As a result of the cervical location of this anomaly, the palatal groove has the potential to harbor bacteria and debris leading to a local inflammatory reaction. Once a breach occurs in the periodontal attachment and the groove is involved, a selfsustaining localized periodontal pocket can develop along the length of the groove  .
Palatal groove on maxillary lateral incisors often present a diagnostic and treatment planning challenge due to the combined endodontic-periodontic lesion. Use of accurate diagnostic aids is essential to arrive at a correct diagnosis as early as possible. Periapical radiographs provides only a two dimensional image and hence they are not sufficient to provide information on the actual size of the lesions  . In 1972, Godfrey Hounsfield introduced the Computed Tomography.
In recent days, three dimensional reconstructed images by CT (spiral-CT) are routinely used in the field of endodontics to define the individual aspects of complex anatomy, plan interventions and follow results. They may have advantages over conventional techniques for the amount of detailed information they can provide on specific cases.
This paper illustrates a case of endo-perio lesion involving a maxillary right lateral incisor caused due to the presence of a deep palatal groove. A combined treatment approach was planned involving endodontic therapy and periodontal surgical management using spiral-CT as a diagnostic aid.
| Case study|| |
A 20 year old male reported to the Department of Conservative dentistry and Endodontics, The Oxford Dental College, Hospital and Research Center, Bangalore, with a chief complaint of pain and associated pus discharge from the palatal gingiva in the region of the maxillary right lateral incisor since 4 months. There was no history of trauma to the maxillary anterior region and the medical history was non-contributory.
Clinical examination revealed a facial parulis on the labial gingival surface associated with the maxillary right lateral incisor [Figure 1]. On periodontal probing, a palatal groove was detected associated with a pocket of 10mm in depth. At all other points around the tooth, the sulcus depth was normal. The tooth had no significant mobility. Thermal and electric pulp vitality tests gave negative response.
Periapical radiographs revealed an extensive periradicular radiolucency involving the apical two-thirds of the root with angular bone loss on the distal aspect of the maxillary right lateral incisor [Figure 2]. An attempt was made to trace the palatal groove through the palatal gingiva with a gutta percha cone [Figure 3].
The periapical radiograph revealed only the extent of the groove. Neither the depth of the groove nor the presence/ absence of any communication between the groove and the root canal could be detected. In order to confirm these findings, a Spiral CT scan (Syngo, Siemens, Berlin) was planned[Figure 4].
Spiral-CT scan revealed that the groove extended upto the middle third of the root and the depth of the groove deepened as it continued apically. There was a communication between the groove and the canal in the middle third of the root [Figure 5]. The scan also revealed the presence of similar grooves on the maxillary central incisors and left maxillary lateral incisor as well, but these grooves were shallow and did not communicate with the root canal.
Based on the clinical and radiographic findings, a diagnosis of pulp necrosis, suppurative apical periodontitis and moderate localized periodontitis secondary to the palatal groove was established. Treatment plan consisted of root canal therapy and surgical curettage of the periodontal defect.
Access opening was performed on the maxillary right lateral incisor and the root canal was explored with a no. 15 K file to establish the glide path. A pulp stone around 4mm in length, was encountered in the coronal third of the canal which was removed using a no. 15 H file[Figure 6]. Working length was determined following which the canal was cleaned and shaped using Hybrid instrumentation with gates glidden drills and NiTi hand files (Dentsply Maillefer, Switzerland). Copious irrigation with 3 % sodium hypochlorite was done at every step of instrumentation. 17% EDTA was used to remove the smear layer. Canal was dried using paper points following which calcium hydroxide paste was placed as an intracanal medicament and the access opening was sealed with IRM [Figure 7].
At the next visit, one week later signs and symptoms of the acute phase were absent. Obturation was completed with cold lateral compaction using guttapercha and AH-plus sealer (Dentsply Maillefer, Switzerland). The access cavity was restored with light cure composite resin (3M ESPE, USA). [Figure 8]
Patient was recalled after 1 month. At the follow-up visit, the facial sinus tract was still present and there was pus discharge from the palatal gingiva adjacent to the groove. After consultation with the periodontist, an exploratory surgery was planned.
2% Lidocaine hydrochloride with 1:200,000 epinephrine (Astra Zeneca Pharma, India) was administered followed by reflection of a labial and palatal full thickness flap that revealed fenestration of the cortical plate on both the sides and palatal groove on the palatal side [Figure 9].
The bony defect and granulation tissue was debrided. Odontoplasty was performed on the root surface to eliminate the groove.
The bony crypt was filled [Figure 10] with a biphasic hydroxyapatite-beta tricalcium phosphate bone graft (Ossifi TM , Holland) following which a bioresorbable collagen membrane (Healiguide TM , India) was placed over the graft [Figure 11] and the flaps were reapproximated and sutured.
Patient was prescribed antibiotics and analgesics and a mouthwash containing 0.2% of chlorhexidine gluconate. Tooth was splinted with a fiber reinforced bond (Ribbond, USA) for a period of 3 weeks. At the recall visit, post-surgical healing was satisfactory and the sinus tract had healed.
At 8 month follow-up, a 2mm non bleeding sulcus was present adjacent to the palatal groove. Periapical radiograph revealed a significant decrease in periapical radiolucency and initiation of deposition of bone in the osseous defect [Figure 12].
| Discussion|| |
The treatment of a palatal groove presents a clinical challenge to the operator. The variability in size and shape of this anomaly coupled with bacterial invasion may affect both the periodontium and the pulp. Hence, conventional endodontic treatment alone will not be effective because the bacterial etiology is residing extra-radicularly as a selfsustaining lesion  .
The reported long term prognosis of therapy appears to be related to the apical extension of the groove. Shallow grooves may often be treated successfully, while deep grooves present complex endodontic-periodontal problems with a poor prognosis ,. It is important to note that it is the ability to adequately treat the periodontal defect that ultimately determines the prognosis of these teeth  .
In the case presented, the palatal groove was deep and extended to the middle-third of the root which was confirmed with the help of Spiral CT scan. CT provides abundant image information not attainable by either periapical radiograph or panoramic radiograph. Its application for clinical use is very effective for examining and diagnosing regions of interest for endodontic therapy.
CT is an X-ray imaging technique that produces 3D images of an object by using a series of two dimensional (2D) set of image data to mathematically reconstruct a cross-section of it. This system measures the attenuation of X-rays entering the body from many different angles. The computer then reconstructs the part under observation in a series of cross sections or planes. Spiral CT scanners use continuous scanning to generate cross-sectional slices and make a set of 3D images. In this way, the time it takes to produce tomographic pictures is reduced .
Compared with the conventional radiographs, the axial CT images were quite helpful in determining the spatial relationship between the apex and the surrounding bone  . There are several techniques related to CT in the dental field: tuned aperture computed tomography (TACT), and micro-CT, cone beam CT.
Advantages with spiral CT is that the scanned volume also includes the opposite side of the jawbone, a fact that in some of cases made it easier to distinguish between a normal bone pattern with irregular and large trabecular spaces and a lesion.
Drawbacks with CT include the high radiation dose, low resolution, the presence of metallic objects and the financial costs  .
There are several causes of the pulp necrosis in the maxillary right lateral incisor in this case. Certainly, previous trauma to the maxillary anterior region could have resulted in pulp necrosis, but the patient did not recall any earlier injury in that area. The palatal groove could also have played a role in the necrosis of the pulp with periodontal breakdown adjacent to the groove. This is very likely considering the depth of the groove in this case. The more likely explanation, however, is that bacterial contamination of the root canal system as a result of communication between this deep infected groove and the pulp in the cervical or mid-root area ultimately led to pulp necrosis.
In this case, the sinus tract remained after endodontic treatment. Hence, surgical procedures were planned consisting of flap reflection, removal of granulation tissue, scaling and root planing of the groove. The groove was not restored with any material after odontoplasty because using a material to fill the groove resulted in reduced epithelial attachment in that region  .
The combined regenerative procedure using bone graft and a resorbable barrier was selected because of the size of the osseous defect and the fact that the involvement of the lesion compromised both facial and lingual cortical plates. Biphasic hydroxyapatite-beta tricalcium phosphate bone graft was used to fill the osseous defect because of the osteoconductive nature and its ability to act as a mechanical substructure to support the membrane and overlying soft tissues. The use of a bioresorbable guided tissue regeneration membrane was placed over the graft for the treatment of palatal grooves. The combination of regenerative bone matrix and a collagen barrier promotes greater amounts of alveolar bone and periodontal ligament minimizing the formation of junctional epithelium ,,
| Conclusion|| |
This case report involving a maxillary right lateral incisor with a deep palatal groove and associated periodontal and pulpal involvement was managed with a multidisciplinary treatment approach with the use of CT as a diagnostic aid.
In a 8 month follow-up, the sinus tract had resolved, there was 2mm non-bleeding sulcus and signs of bone deposition radiographically, suggesting active healing of the periodontal ligament attachment and alveolar bone.
| Acknowledgments|| |
The authors wish to express their gratitude to Elbit Diagnostic Centre, Bangalore for their help in performing the spiral-CT scan and the Department of Periodontics, The Oxford Dental College, Hospital and Research Center, Bangalore for their valuable participation in this work.
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Department of Conservative Dentistry and Endodontics, The Oxford Dental College, Hospital and Research Center, Bangalore
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]