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Year : 2016  |  Volume : 20  |  Issue : 3  |  Page : 315-319  

Morphological study of proximal root grooves and their influence on periodontal attachment loss

Department of Periodontics, Himachal Institute of Dental Sciences, Paonta Sahib, Himachal Pradesh, India

Date of Submission15-Feb-2015
Date of Acceptance22-Feb-2016
Date of Web Publication4-Jul-2016

Correspondence Address:
Saravpreet Kaur
Department of Periodontics, Himachal Institute of Dental Sciences, Paonta Sahib, Himachal Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-124X.179404

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Background: The etiology of periodontal diseases is multifactorial including both systemic and local causes. Local factors such as grooves on root surfaces contribute a great deal to the causation of periodontal diseases. Materials and Methods: Proximal radicular grooves were studied in 150 extracted maxillary and mandibular anterior teeth. Periodontal attachment loss was measured after staining the root surfaces with 0.1% toluidine blue stain. The relationship of the presence and absence of grooves with periodontal attachment loss was also studied. Results: The prevalence of proximal root grooves was found to be 86.67%. The prevalence of grooves on maxillary teeth was 43.42% and on mandibular teeth was 56.67%. A greater loss of attachment was present on grooved surfaces than on nongrooved surfaces. Conclusion: The proximal radicular grooves present as one of the major etiological factors in periodontal diseases.

Keywords: Attachment loss, dental plaque, proximal radicular grooves, root planning, scaling

How to cite this article:
Kaur S, Gupta R, Dahiya P, Kumar M. Morphological study of proximal root grooves and their influence on periodontal attachment loss. J Indian Soc Periodontol 2016;20:315-9

How to cite this URL:
Kaur S, Gupta R, Dahiya P, Kumar M. Morphological study of proximal root grooves and their influence on periodontal attachment loss. J Indian Soc Periodontol [serial online] 2016 [cited 2021 Aug 3];20:315-9. Available from:

   Introduction Top

The diseases of the periodontium, though being studied since immemorial times, still elude us in terms of their etiological and contributory factors: The various factors responsible for the appearance and occurrence of gingivitis and more importantly periodontitis.

Although the main etiology of periodontal diseases is dental plaque, there are various other factors that are believed to play a contributory role in the causation and progression of periodontal diseases. Factors such as tooth anomaly and restorative and endodontic consideration have been linked to gingival inflammation and attachment and tooth loss.[1]

While potential pathogens may colonize the site for decades without causing the disease, if the local environment changes in a manner that upsets the balance between health and disease, destruction rather than remodeling of the periodontium ensues. “Local factors” have been shown to produce these changes.[2]

Local factors have been defined as anything that influences the periodontal health status at a particular site or sites, with no known systemic effects. These may be anomalies in the root anatomy or iatrogenic features.[3]

The various factors related to the morphology and anatomy of teeth and associated with periodontal attachment loss and periodontal breakdown include inherent anatomic and morphologic features of teeth such as marginal ridge discrepancies, food impaction, cervical enamel projections, open contacts, and pits and grooves on tooth surfaces. Several morphological studies of root shape have attempted to link root shape anomalies with periodontal disease.[4]

Root grooves are developmental anomalies caused by an infolding of the inner enamel epithelium and Hertwig's epithelial root sheath on the tooth surface. Such morphological features compromise patient self-care, favor accumulation of plaque, calculus, and food debris. They facilitate growth and later provide anaerobic condition for bacterial selection and proliferation.[5]

Hence, the anatomic variations in teeth such as grooves on the proximal surfaces of the roots of teeth may cause enhanced periodontal attachment loss thus contributing to causation of periodontal disease. The morphology of the root must be well-known to establish a correct diagnosis and formulate an effective treatment plan.[6]

Hence, there is a need to study the morphological abnormalities and anatomic variations such as grooves.

The present study attempts to thoroughly understand the morphology of the grooves present on the proximal surfaces of the roots of the permanent maxillary and mandibular anterior teeth and also to comprehend the effect of the presence and absence of grooves on the periodontal attachment loss.

   Materials and Methods Top

Sample collection

A total of 150 (75 maxillary and 75 mandibular) teeth were used in the present study. The teeth had been extracted for various reasons and stored in formalin immediately after extraction. The preextraction history of the teeth was unknown. The selected teeth had an intact cementoenamel junction (CEJ), no caries or restorations extending beyond the CEJ, and no visible damage from the extraction. The periodontally involved part of the root was carefully scaled and cleaned in running water. Twenty five teeth of each type were identified: Maxillary and mandibular central incisors, lateral incisors, and canines. First, teeth were identified on the basis of the jaw, (i.e., maxillary or mandibular) and then on the type (central incisors, lateral incisors, or canines) and the side to which they belong (i.e., right or left).

The side of each sample was determined on the basis of the differences in the morphology such as the difference in crown morphology of the mesial and distal surfaces, the bend of the root apex toward the distal side in most teeth, the differences in the location of the CEJ on mesial and distal surfaces.

Staining of the samples and measurement of loss of attachment

After side determination, toluidine blue staining was done. The roots of the sample were immersed in the 0.1% toluidine blue stain for 10 s followed by which the sample was washed under running water to wash off the unfixated; thus staining the area where periodontal attachment existed [Figure 1].
Figure 1: Stained portion and marked groove on a maxillary canine

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Then, loss of attachment (LOA) was measured along the long axis of the tooth as the distance from the CEJ to the most coronal level of the stained periodontal ligament.

Marking the groove

A William's surveyor [Figure 2] with a lead point was used to mark each tooth on the mesial and distal surfaces by moving a tooth at right angles across the lead. Where a concavity existed, the lead contacted the two surfaces on either side of the concavity, producing two lead lines.
Figure 2: William's surveyor used for marking the groove

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Measurement of various dimensions

Using a digital Vernier calliper, the following measurements were made:

  • The length of the groove from the cervical to apical end
  • The width of the groove was measured at the midpoint of the groove
  • Distance of the origin of the groove from the CEJ, i.e., the position of the groove relative to the CEJ
  • Depth of the groove is measured at the midpoint of the length of the groove.

Statistical analysis

The collected data were statistically analyzed. The mean and standard deviations of the parameters tested were estimated for all the sample types. Analysis of variance and paired t-test were carried out, and the results were considered to be statistically significant if the P < 0.01.

   Results Top

A total of 300 proximal surfaces of 150 permanent maxillary (75) and mandibular (75) anterior teeth central incisors, lateral incisors, and canines were surveyed. The prevalence of proximal root grooves was 86.67%. The prevalence of grooves on maxillary teeth was 43.42% and on mandibular teeth was 56.67%.

Prevalence of grooves according to type of teeth

The prevalence of grooves for maxillary central incisors, lateral incisors, and canines was 56%, 64%, and 78%, respectively, and that for mandibular teeth was 88% for mandibular central incisor, 90% for mandibular lateral incisor, and 80% for mandibular canines. The highest prevalence is seen for mandibular lateral incisors, i.e., 90% of mandibular lateral incisors were grooved. Maxillary central incisor shows the least prevalence of proximal root grooves, i.e., only 56% of the total surfaces of maxillary lateral incisors were grooved.

Prevalence of grooves according to point of origin

In case of maxillary anteriors, 37.3% of the proximal radicular grooves were seen to originate at the CEJ whereas in case of mandibular anteriors, 55.03% of the grooves originated at the CEJ.

Prevalence of grooves according to surfaces

Out of the total 300 surfaces that were examined, 228 had grooves out of which 110 (48.24%) were mesial and 118 (51.75%) were distal. In case of maxillary arch, the prevalence of proximal root grooves on mesial surface was 64% and on distal surface was 68%; for mandibular teeth the prevalence values were 82.67% and 89.33% for mesial and distal surfaces, respectively. Distal surfaces of mandibular anteriors show highest prevalence, i.e., 68% of all the distal surfaces of maxillary arch were grooved. Mesial surfaces of maxillary anteriors have least propensity of having a proximal root groove (64%) of all the mesial surfaces of maxillary teeth were grooved.

Width of grooves

The greatest width was observed in case of maxillary canine (4.3 mm) and the least width was seen in case of maxillary central incisor (0.8 mm). The mean width for maxillary central incisor and mandibular incisors was seen to be 1.97 mm and 2.20 mm, respectively, and that for maxillary and mandibular lateral incisors was 2.12 and 2.29 mm, respectively. The readings for canines were 2.49 mm and 2.42 mm for maxillary and mandibular canine, respectively.

Depth of grooves

The greatest depth was seen for mandibular canine, i.e., 1.38 mm, and the smallest depth was seen for maxillary canine, i.e., 0.05 mm.

The findings have been summarized in [Table 1].
Table 1: Mean prevalence of grooves and mean values of all parameters (width, length, and depth) with standard deviations

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Loss of attachment

The minimum value of LOA for all tooth types was 0 and the maximum LOA was observed in a maxillary canine, i.e., 9.79 mm. The mean LOA in case of maxillary central incisor, lateral incisor, and canine was observed to be 2.57, 3.34, and 4.26 mm, respectively. The values for mandibular teeth were 3.42, 3.78, and 3.47 mm for mandibular central incisor, lateral incisor, and canine, respectively.

Loss of attachment on grooved and nongrooved surfaces

The LOA on grooved surfaces is greater than LOA on nongrooved surfaces in case of maxillary central incisor, maxillary canine, mandibular central incisor, mandibular lateral incisor, and mandibular canine and this variation is statistically significant as shown in [Table 2] [Figure 3]. The maxillary central incisors showed the least prevalence of grooves and also the least mean LOA whereas the mandibular lateral incisor shows the highest prevalence of grooves with a mean LOA of 3.78 mm as depicted in [Table 2]. The maximum mean LOA is observed in case of maxillary canine, i.e., 4.26 mm.
Table 2: Loss of attachment on grooved and nongrooved surfaces and comparison with prevalence of grooves

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Figure 3: Mean loss of Attachment on grooved and nongrooved surfaces

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   Discussion Top

The present study was carried out with the objective of surveying the morphology of the roots of 150 extracted teeth which included maxillary and mandibular anteriors (25 each). The teeth were selected from a formalin stored pool of extracted teeth whose preextraction history was unknown. A morphological survey was performed for the proximal root grooves and the influence of the grooves on periodontal attachment loss was also evaluated.

A total of 300 proximal surfaces of 150 permanent maxillary (75) and 150 mandibular (75) anterior teeth (central incisors, lateral incisors, and canines) were surveyed. The prevalence of proximal root grooves was seen to be 86.67% of the teeth examined (130 out of the total 150) and 76% of all the surfaces (228 surfaces out of 300). These findings were consistent with those seen in a study conducted by Bhusari and Chopra.[7]

The highest prevalence of grooves was seen in case of mandibular lateral incisor whereas the least prevalence was seen in case of maxillary central incisors. The distal surfaces were seen to have a higher prevalence of grooves on all kind of teeth apart from mandibular central incisor which showed an equal prevalence of radicular grooves on mesial and distal sides. The mandibular canines displayed 17.54% of the total grooves which was less than that of lateral incisors (19.74%) and also central incisors (19.30%), and this finding is in line with the study conducted by Bhusari and Chopra.[7] Mandibular canines showed a lower percentage of grooves than mandibular lateral incisors, i.e., 17.54%; 80% of these teeth had grooves.

Removal of calculus from all the exposed surfaces of the root is very necessary if periodontal health is to be achieved. Studies have demonstrated difficulty in calculus removal in case of sulcus depth more than 3 mm.[8],[9] The results of several studies have concluded that the areas of root surfaces most often harboring residual calculus after scaling and root planing was the proximal root surface of both anterior and posterior teeth.[10],[11] The results of the present study indicate that 37.3% of the maxillary grooves and 55.03% of the mandibular grooves originate at the CEJ and 62.6% and 44.96% of maxillary and mandibular grooves, respectively, to originate apical to CEJ. The findings relating to the maxillary teeth are in agreement with the study of Fox and Bosworth.[12] This data supports the fact that deep pockets combined with proximal root grooves would definitely complicate calculus removal.

Another aspect evaluated in the present study was the influence of the presence or absence of proximal root grooves on the attachment loss occurring on the proximal surfaces. The level of attachment is defined as the distance between the base of the pocket and a fixed point on the crown, i.e., the CEJ. Changes in the level of attachment can be caused only by gain or LOA and thus provide a better indication of periodontal destruction.[13]

Although root grooves increase the attachment area and produce a root shape that is more resistant to torquing forces, but after attachment loss takes place, they help in harboring plaque and calculus.[14]

In the present study, all 57 mandibular teeth with proximal root grooves on both the surfaces also show attachment loss on both the surfaces and in case of maxillary teeth 41 teeth show grooves on both surfaces and 53 teeth show LOA on both surfaces. While considering teeth with LOA on only one surface, 9 mandibular and 13 maxillary teeth showed LOA on only one surface and 17 maxillary and 15 mandibular teeth showed grooves on one surface.

Out of the total 150 teeth, 130 teeth showed grooves (86.67%) and 13.33% (20 teeth) did not show grooves. Out of the 130 teeth, 85 teeth (65.38%) showed grooving, as well as LOA on both surfaces and 11 teeth (8.46%), showed grooving and attachment loss on one surface, which harbored the groove. About 15 teeth (11.53%) were observed to have grooves only on one surface but LOA on both surfaces.

About 9 teeth (6.92%) though did not show the presence of grooves did show LOA, the mean LOA in these teeth was 3.73 mm. This was consistent with the observations made by Bhusari and Chopra. This may indicate that there may be other factors more dominant than anatomic variations like anaerobic environment and site specificity at advanced stages of disease.[7]

Remaining 10 teeth (7.69%) with grooves did not show LOA. This could be attributed to the fact that these teeth might have been lost due to nonperiodontal reasons such as avulsion due to tooth trauma and extractions to meet the requirements of orthodontic and prosthodontic reasons.[7]

Highly significant differences were observed in the mean LOA between grooved and nongrooved surfaces as shown in [Table 2]. When comparison was made between the total mean LOA on grooved surfaces and on the nongrooved surfaces, it was observed that the grooved surfaces showed a mean LOA of 3.86 mm (0–9.79 mm) whereas the nongrooved surfaces showed a mean LOA of 1.83 mm (0–9.35 mm). This is in accordance with the study conducted by Leknes et al.[15]

When a comparison was made between the mean LOA values and prevalence of grooves on various teeth as shown in [Table 2], it was observed that maxillary central incisors show the lowest prevalence of grooves and also the least mean LOA whereas the mandibular lateral incisor shows maximum mean LOA and the highest prevalence of grooving.

Thus, the mean total LOA in case of grooved surfaces is higher than the mean total LOA occurring on nongrooved surfaces. Similar findings relating the LOA to presence or absence of proximal root grooves have been seen in studies by Bhusari and Chopra and Leknes et al.[7],[15]

The only exception was the maxillary lateral incisor in which the LOA was higher on nongrooved surfaces but that may be attributed to the fact that attachment loss may have occurred due to the presence of other etiological factors such as bacterial selection due to a strict anaerobic environment. These factors become more dominant than local factors such as radicular grooves during the advanced stages of the disease. These findings endorse the study of Leknes et al.[15]

The finding of the present study that proximal radicular grooves are a significant etiological factor in causation of periodontal attachment loss thus leading to periodontitis is reinforced by a study conducted by Albandar et al.,[16] according to which the occurrence of more than 3 mm of attachment loss is indicative of periodontal disease. The mean LOA on the surfaces with grooves is seen to be 3.86 mm, and this value points toward the fact that radicular grooves on proximal surfaces could be a contributing factor in periodontitis as on the nongrooved surfaces the mean attachment loss that was seen was <l mm (1.83 mm).

Moreover, in the study conducted by Albandar et al., mandibular incisors were said to be the teeth with the highest prevalence of periodontal diseases.[16] In the present study, the surfaces of mandibular incisors depicting a high prevalence of radicular grooves showed a mean attachment loss of more than 3 mm indicating a periodontal disease that could be caused by the presence of grooves. Thus, in case of mandibular incisors, root grooves may act as a major etiological factor.

The most likely explanation for the negative effects of grooves and their tendency to cause LOA may be considered to be related to their plaque promoting effect. Lie et al. demonstrated the effect of acquired plaque irregularities upon the initiation of supragingival plaque formation and observed early plaque growth when grooves and pits were created on artificial hydroxyapatite splint surfaces.[17]

Grooves may facilitate plaque growth by providing surface areas sheltered from the efforts for maintenance of oral hygiene and also from the host defense mechanism. Due to the formation of these sheltered areas due to presence of grooves, the health of the periodontium is greatly compromised. Anaerobic conditions may later be established inside the groove, thus influencing the bacterial selection and growth leading to harboring of periodontopathogenic bacteria.

The complete removal of calculus and plaque from the subgingival root grooves is more difficult because of the shape of most curettes. The mean width of grooves is 2.27 mm ranging from 0.8 to 4.3 mm. A highly sensitive tactile perception is required on the part of the practitioner to negotiate this difficult area of root grooves. After a proximal root concavity or groove which can compromise the patient's ability to perform effective plaque control is identified by a practitioner, an adjunctive oral hygiene aid should be prescribed apart from the dental floss as floss can also bridge the concavity.[18]

Another implication of the presence of proximal root grooves is seen in periodontal regenerative surgery procedures. Concavities and grooves in the cervical area may prevent optimal adaptation of the barrier membranes and consequently compromise its barrier function of preventing apical migration of junctional epithelium on the root surface. Thus, teeth with proximal grooves and furcation involvement may represent a special challenge in guided tissue regeneration therapy.[19]

The results obtained from the present study indicate that the maxillary and mandibular anterior teeth usually present with grooves on the proximal surfaces of their roots. These grooves show large variations with regard to their prevalence in different tooth types and their morphological features, (i.e., location of point of origin, length, width, and depth). The observations made in the study also support the hypothesis that proximal root grooves, when present play a significant role in LOA.

   Conclusion Top

The proximal radicular grooves have presented as one of the local etiologic factors in the causation of periodontal attachment loss. Thus, they should be considered in periodontal diagnosis, prognosis, and treatment planning. The relationship between the presence of grooves on the proximal root surfaces and LOA on those surfaces has been established in the present morphological study.In vivo studies need to be conducted to substantiate the observed correlations and also to provide a better comprehension of the effect of proximal radicular grooves on periodontal attachment loss.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Slots J. Bacterial specificity in adult periodontitis. A summary of recent work. J Clin Periodontol 1986;13:912-7.  Back to cited text no. 1
Socransky SS, Haffajee AD. Microbial mechanisms in the pathogenesis of destructive periodontal diseases: A critical assessment. J Periodontal Res 1991;26(3 Pt 2):195-212.  Back to cited text no. 2
Kornman KS, Löe H. The role of local factors in the etiology of periodontal diseases. Periodontol 2000 1993;2:83-97.  Back to cited text no. 3
Blieden TM. Tooth-related issues. Ann Periodontol 1999;4:91-7.  Back to cited text no. 4
Leknes KN. The influence of anatomic and iatrogenic root surface characteristics on bacterial colonization and periodontal destruction: A review. J Periodontol 1997;68:507-16.  Back to cited text no. 5
Matthews DC, Tabesh M. Detection of localized tooth-related factors that predispose to periodontal infections. Periodontol 2000 2004;34:136-50.  Back to cited text no. 6
Bhusari PA, Chopra R. A morphological survey of root grooves and their influence on periodontal attachment loss. Saudi Dent J 2011;23:91-7.  Back to cited text no. 7
Rabbani GM, Ash MM Jr., Caffesse RG. The effectiveness of subgingival scaling and root planing in calculus removal. J Periodontol 1981;52:119-23.  Back to cited text no. 8
Jones WA, O'Leary TJ. The effectiveness of in vivo root planing in removing bacterial endotoxin from the roots of periodontally involved teeth. J Periodontol 1978;49:337-42.  Back to cited text no. 9
Tagge DL, O'Leary TJ, El-Kafrawy AH. The clinical and histological response of periodontal pockets to root planing and oral hygiene. J Periodontol 1975;46:527-33.  Back to cited text no. 10
Gellin RG, Miller MC, Javed T, Engler WO, Mishkin DJ. The effectiveness of the Titan-S sonic scaler versus curettes in the removal of subgingival calculus. A human surgical evaluation. J Periodontol 1986;57:672-80.  Back to cited text no. 11
Fox SC, Bosworth BL. A morphological survey of proximal root concavities: A consideration in periodontal therapy. J Am Dent Assoc 1987;114:811-4.  Back to cited text no. 12
Andreana S. A combined approach for treatment of developmental groove associated periodontal defect. A case report. J Periodontol 1998;69:601-7.  Back to cited text no. 13
Novak KF, Goodman SF, Takei HH. Determination of Prognosis. In: Newman M, Takei H, Klokkevold P, Carranza F, editors. Carranza's Clinical Periodontology. 10th ed. St. Louis, Missouri: Saunders, Elsevier; 2006. p. 620.  Back to cited text no. 14
Leknes KN, Lie T, Selvig KA. Root grooves: A risk factor in periodontal attachment loss. J Periodontol 1994;65:859-63.  Back to cited text no. 15
Albandar JM, Brunelle JA, Kingman A. Destructive periodontal disease in adults 30 years of age and older in the United States, 1988-1994. J Periodontol 1999;70:13-29.  Back to cited text no. 16
Lie T. Early dental plaque morphogenesis. A scanning electron microscope study using the hydroxyapatite splint model and a low-sucrose diet. J Periodontal Res 1977;12:73-89.  Back to cited text no. 17
Smukler H, Nager MC, Tolmie PC. Interproximal tooth morphology and its effect on plaque removal. Quintessence Int 1989;20:249-55.  Back to cited text no. 18
Proestakis G, Bratthall G, Söderholm G, Kullendorff B, Gröndahl K, Rohlin M, et al. Guided tissue regeneration in the treatment of infrabony defects on maxillary premolars. A pilot study. J Clin Periodontol 1992;19:766-73.  Back to cited text no. 19


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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