Embrasure morphology and central papilla recession.

BACKGROUND: The aim of this study was to ascertain the effects of vertical and horizontal distances between the maxillary central incisors on the presence of interproximal dental papilla and to assess the association between the embrasure morphology and central papilla recession.
MATERIALS AND METHODS: The central papilla was visually assessed in 50 subjects using the standardized periapical radiographs of maxillary central incisors. The following vertical distances were measured; distance from the contact point to papilla tip, CP to proximal cementoenamel (pCEJ) junction, bone crest to CP (BC-CP) and BC-PT. The horizontal distance measured was interdental width (IDW) at pCEJ level. The measurements were recorded using a digital electronic caliper.
RESULTS: Significant association between the embrasure morphology and central papilla recession was observed for all study groups. All the interdental variables were significantly related to the presence of interdental papillae, with BC-CP distance being the strongest determinant of central papilla presence. The percentage of interdental papilla presence was 100% when the BC-CP distance was ≤6 mm and IDW ranged between 0.5 and 1.5 mm. Central papilla recession was observed most frequently with wide-long and narrow-long embrasure morphology.
CONCLUSION: In relation to maxillary central incisors, all the interdental variables have significant influences on the presence of interdental papillae, with distance from BC to CP being the strongest determinant of central papilla presence.

INTRODUCTION

The presence of the central papilla is considered to be a key esthetic factor in the smile of any individual.[1] The esthetic appearance of the maxillary anterior dentition is largely determined by the shape, size and health of the interdental papilla. Thus, the presence or absence of the interdental papilla is of great concern to the patients as well as dentists, especially in the areas of maxillary central incisors (defined as central papilla).[2]

Maxillary central incisors because of their location in the midline and being the most prominent teeth are first noticeable in appearance.[3] The interdental papilla in the incisor region, usually assumes the shape of a pyramidal papilla or it may appear as a slight gingival “col”, depending on the location of the contact area and height of the gingiva.[4567] A number of studies have been carried out to discover the factors determining the presence and maintenance of the papilla. One such factor is the distance from the interdental contact point (CP) to the alveolar bone crest (BC). It has been noted that the papilla are almost always present when the distance between the CP and BC is 5 mm or less but the papilla are typically absent when the CP-BC distance is 7 mm or more.[8] In addition to the CP-BC distance, other less well-understood factors viz., volume of the embrasure space, angulations of the roots of the adjacent teeth, crown shape, space between adjacent teeth and the course of the cementoenamel junction etc., also help to determine the presence of the interdental papilla.[89101112]

The aim of the present study was to confirm the data in the literature to ascertain the effects of vertical and horizontal distances between the maxillary central incisors on the presence of interproximal dental papilla and to assess the association between the embrasure morphology and central papilla recession.

MATERIALS AND METHODS

A total of 50 healthy adults between the age group of 20 and 35 years with fully erupted permanent dentition were selected. Inclusion criteria were well-aligned maxillary central incisors with no spacing, no crowding, no rotation and no intrusion or extrusion and healthy gingiva with plaque[13] and gingival index[14] of 0-1. Patients with systemic compromise that included pregnancy or a history of taking medications known to increase the risk of gingival hyperplasia were excluded from the study. Maxillary central incisors with the presence of an artificial crown, proximal cervical restorations or abrasions, a history of surgery or open contact or crowding observed visually without aid, angular BC in mesiodistal direction and distance between BC and CP more than 8 mm, even though the gingiva was healthy, were also not included in this study.

Study protocol

After the initial screening of the subjects, the clinical parameters (i.e., plaque index[13] and gingival index[14]) were recorded while they were seated on a dental chair comfortably in an upright position. A visual examination was performed to detect the interdental papilla between the maxillary central incisors. If no space was visible apical to the CP/area, the papilla was recorded as being present without central papilla recession [Figure 1]. If there was a space visible apical to the CP/area, it was filled with the temporary semi-soft radiopaque material (CavitTM G [3M ESPE Dental Products, St. Paul, MN 55144-1000, USA]), so that papilla tip (PT) could be visualized on the intraoral periapical (IOPA) radiograph and was recorded as central papilla recession [Figure 2].

Figure 1

Subject without central papilla recession

Figure 2

Subject with central papilla recession

Then, a good quality IOPA radiograph of the maxillary central incisors was taken [Figures 3a, b, 4a and b] with the paralleling technique with the help of X-ray film holder. Further, measurements were made on the radiographs using a digital electronic caliper (My Cal Absolute, Mitutoyo, Japan) [Figure 5].

Figure 3

(a) Intraoral periapical radiograph w.r.t. maxillary central incisors of the subject without central papilla recession; (b) Intraoral periapical radiograph w.r.t. maxillary central incisors of the subject without central papilla recession. The horizontal lines indicate the following locations from top to bottom, bone crest, proximal cementoenamel junction, papilla tip and contact point

Figure 4

(a) Intraoral periapical radiograph w.r.t. maxillary central incisors of the subject with central papilla recession; (b) Intraoral periapical radiograph w.r.t. maxillary central incisors of the subject with central papilla recession. The horizontal lines indicate the following locations from top to bottom: Bone crest, proximal cementoenamel junction, papilla tip and contact point

Figure 5

Digital electronic caliper

Vertical distances measured on radiographs included distance from CP to PT, CP to proximal cementoenamel junction (CP-pCEJ), BC-CP and BC-PT. Horizontal distance measured was the interdental width (IDW) between two maxillary central incisors at the pCEJ junction level.

Data analysis

A total of 50 subjects which consists of 20 males and 30 females in the age group of 20-35 years (mean age 23.76 years) with fully erupted permanent dentition were included in the study. For the purpose of analysis, the embrasure morphology of the study subjects was divided into four groups according to their width (IDW) and height (H = CP-pCEJ) of interdental papillae: Narrow-long (IDW < 2 mm and H > 4 mm), narrow-short (IDW < 2 mm and H < 4 mm), wide-long (IDW > 2 mm and H > 4 mm) and wide-short (IDW > 2 mm and H < 4 mm).

Commercially available statistical software SPSS for windows (version 13.0; SPSS Inc., Chicago, IL, USA) was used to analyze the data, which is presented as the mean ± standard deviation. The Mann-Whitney test was used for the comparison of two variables such as groups with and without central papilla recession. A parametric analysis of variance test was used to compare the differences between the means of two or more groups (i.e., amongst the four study groups).

RESULTS

Out of the 50 subjects, 5 subjects were presented with central papilla recession and 45 subjects presented without central papilla recession. A comparison of the values of vertical and horizontal measurements between the subjects with and without central papilla recession is summarized in Table 1. In all the subjects with central papilla recession, distance between CP-PT, CP-pCEJ, BC-CP and IDW distance were significantly greater than subjects without central papilla recession. Furthermore, the ratio between the height (H = CP-pCEJ) and width (IDW) of interdental papilla was greater in subjects with central papilla recession, but the difference was not statistically significant when compared with subjects without central papilla recession.

Table 1

Comparison of mean values of vertical and horizontal measurements between the subjects with and without central papilla recession

Table 2 shows the percentage of interdental papillae presence according to distance from BC to CP. Interdental papillae were present in 100% (35/35) of cases when the distance from the CP-BC ranged between 3 and 6 mm, 81.8% (9/11) of cases when the distance ranged between 6 and 7 mm and 25% (1/4) of cases when the distance ranged between 7 and 8 mm. Therefore, with the increasing distance from the BC to CP, the number of papillae that filled the interproximal space decreased.

Table 2

Percentage of interdental papillae presence according to distance from the BC to CP

Similarly, when the percentage of interdental papillae presence according to IDW was analyzed [Table 3], it was observed that interdental papillae were present in 100% (13/13) of cases when the IDW ranged between 0.5 and 1.5 mm, 95.6% (22/23) of cases when the distance ranged between 1.5 and 2.0 mm, 81.8% (9/11) of cases when the distance ranged between 2.0 and 2.5 mm and 33.3% (1/3) of cases when the distance ranged between 2.5 and 3.0 mm.

Table 3

Percentage of interdental papillae presence according to interdental width

Table 4 shows the percentage of interdental papillae presence associated with combined effect of the distance from the BC to CP and the IDW. Percentage of papillae presence were 100%, only when the distance from BC to CP ranged between 3 and 6 mm and the IDW ranged between 0.5 and 1.5 mm. Further increase in the BC-CP distance and IDW was associated with a decrease in the percentage of papilla presence.

Table 4

Percentage of interdental papillae presence according to the distance from the BC to CP and IDW

The morphologic differences of the four groups that were established according to width (IDW) and height (H = CP-pCEJ) of interdental papillae are summarized in Table 5. In Narrow-Long (IDW < 2 mm and H >4 mm) group, out of nine subjects (mean age 23.11 ± 1.53 years), only one subject presented with central papilla recession. The mean vertical distance (in mm) between the CP-pCEJ was 4.58 ± 0.29 and the mean horizontal distance, i.e., IDW was 1.63 ± 0.28. The mean value for other variables, i.e., vertical distance between the CP-PT was 0.26 ± 0.80, BC-CP was 6.08 ± 0.44 and BC-PT was 5.81 ± 0.83, respectively.

Table 5

Comparison of mean values of vertical and horizontal measurements of four study groups, categorized according to width (IDW) and height (H=CP-pCEJ distance) of interdental papillae

In Narrow-Short group, none out of 27 subjects (mean age 23.89 ± 4.04 years) presented with central papilla recession. The mean vertical distance (in mm) between the CP-pCEJ was 3.11 ± 0.66 and the mean horizontal distance, i.e., IDW was 1.48 ± 0.32. The mean value for other variables, i.e., vertical distance between the CP-PT was 0, BC-CP and BC-PT was 4.84 ± 0.98.

In wide-long group, out of 11 subjects (mean age 23.00 ± 3.22 years), four subjects were presented with the central papilla recession. The mean vertical distance (in mm) between CP and pCEJ was 5.15 ± 0.69 and the mean horizontal distance, i.e., IDW was 2.36 ± 0.21. The mean value for other variables, i.e., vertical distance between the CP-PT was 1.25 ± 1.75, BC-CP was 6.77 ± 0.67 and BC-PT was 5.51 ± 1.37, respectively.

In wide-short group, out of three subjects (mean age 26.33 ± 3.05 years), none of the subject was presented with the central papilla recession. The mean vertical distance (in mm) between the CP and pCEJ was 3.70 ± 0.24 and the mean horizontal distance, i.e., IDW was 2.22 ± 0.17. The mean value for other variables, i.e., vertical distance between the CP-PT was 0, BC-CP and BC-PT was 5.13 ± 0.18.

When the comparison of the basic characteristics of embrasure morphology of the four study groups (narrow-long, narrow-short, wide-long and wide-short) was put to statistical analysis, the mean differences between four study groups with respect to CP-pCEJ, CP-PT, BC-CP and IDW were found to be highly significant (P ≤ 0.001). The difference between the study groups in relation to central papilla recession was also found to be significant (P = 0.008), while the difference in the study groups with respect to age (P = 0.490) and BC-PT (P = 0.073) were statistically non-significant.

DISCUSSION

The presence or absence of the interdental papilla is of great concern to the patients as well as the Dentists, especially in the area of maxillary central incisors (defined as central papilla).[2] In the current study, all the interdental variables were observed to be significantly related to the presence of interdental papilla, though BC-CP was reported to be the strongest determinant of central papilla presence.

The current study has several methodologic strengths such as the data was collected at a single papilla location, the central maxillary papilla, the most important location for dental esthetics. The subjects included had normal teeth, i.e., well-aligned maxillary central incisors with healthy gingiva. The subjects with any previous history of surgery in anterior maxillary area, presence of artificial crown or restorations, open contact or crowding in relation to maxillary central incisors were excluded from the study. These criteria decreased the statistical “noise” that would have been caused by using a more inclusive sample of subjects and therefore, increased the statistical precision of the results. Orthodontically treated teeth were also excluded because orthodontic treatment can artificially suppress the interdental soft-tissue, deform interdental papillae and reshape the interdental contact area. Furthermore, the subjects with a BC-CP distance greater than 8 mm were excluded, because all such subjects would have central papilla recession.

In previous studies, papillary height was measured by bone sounding, with the patient under local anesthesia; however, this method is invasive and only allows for buccal measurement.[8910] The thickness of the masticatory mucosa and gingivae can be determined ultrasonically, but this measurement does not include interdental papillary height.[1516] Therefore, the use of the standardized periapical radiographs was adopted, which is a simple, accurate and non-invasive method of measurement that is readily accepted by the subjects. In addition, the use of radiopaque material permitted the measurement of the interdental papilla in relation to the alveolar BC.[11718192021]

Many of the studies,[8910171822] like the present one, have showed a significant relationship between BC and CP distance and the presence of the interdental papilla. In the present study, the papilla was found to be present 100% of time when the BC-CP distance ranged between 3 and 6 mm, 81.8% of time when distance ranged between 6 and 7 mm and 25% of time when distance ranged between 7 and 8 mm. Chang[17] stated that when the BC-CP distance was 5 mm, the papilla was present 51% of the time, whereas at 7 mm, the papilla was present only 10% of the time. In a recent study, Chen et al.[18] reported that when all interdental variables in the anterior maxillary region were taken together, BC-CP distance was the only significant factor that was related to the presence of interdental papillae.

There is a paucity of literature on the relationship of IDW with the presence of interdental papilla.[2324] In the current study, it was found that the interdental papilla was always present when the IDW between maxillary central incisors ranged between 0.5 and 1.5 mm. The number of papillae that filled the interproximal space decreased with the increasing IDW, with the persistence of only 33.3% when the IDW ranged between 2.5 and 3.0 mm.

Furthermore, in this study, the percentage of interdental papilla presence was observed when both height and width, i.e., distance from BC to CP and IDW, respectively, were taken into account. When the BC-CP distance ranged between 3 and 6 mm and IDW ranged between 0.5 and 1.5 mm, the percentage of papillae presence was 100%. The incidence of the interdental papilla further decreased with increasing BC-CP distance and IDW. A similar study was reported by Cho et al.,[23] in which the author found that the dimensions that showed almost 100% papillae formation were 4 mm × (1.5-2.5) mm and 5 mm × 1.5 mm (BC-CP × IDW).

In all the subjects with central papilla recession (n = 5), distance between CP-PT, CP-pCEJ, BC-CP and IDW distance were significantly greater than subjects without central papilla recession. Also, the ratio between the height from CP-pCEJ (H) and IDW was also greater in subjects with central papilla recession, but the difference was not statistically significant when compared to subjects without central papilla recession. This observation was in accordance with the study by Chang,[19] though they have reported a greater ratio between H and IDW in subjects without central papilla recession.

To further elucidate the effect of embrasure morphologies on central papilla recession, subjects were categorized into four groups according to width (IDW) and height (H = CP-pCEJ) of interdental papilla: Narrow-long, narrow-short, wide-long and wide-short. The highest number of subjects were observed in the narrow-short group (n = 27) than in any of the other groups. This may reflect the greater natural prevalence of the narrow-short embrasure morphology.[21720] Also, a significant association between the embrasure morphology and central papilla recession was observed. The subjects with the central papilla recession belonged to wide-long and narrow-long embrasure morphology, with none of the subjects in wide-short and narrow-short group, presenting with the central papilla recession. Statistically significant differences were observed between the study groups with respect to IDW, CP-pCEJ, CP-PT and BC-CP distance. Furthermore, the BC-CP distance reported in these two groups (i.e., wide-short and narrow-short) was ≤6 mm. This finding further emphasizes the importance of distance from BC to CP on the incidence of interdental papilla.

Ryser et al.[25] reported that baseline papilla and bone levels on the adjacent natural teeth were strong predictors of papilla recession 1-2 years after the implant was inserted. Therefore, a thorough understanding of the morphology might be useful in predicting the probability of successful papilla formation after implant procedure.

There has also been found an association between age and central papilla recession in previous studies,[21920] but in the present study, no significant association between age and central papilla recession was reported. The variation could possibly be attributed to the narrower range of age group (i.e., 20-35 years) taken for the study. Moreover, a small sample size (n = 50) can also be seen as a possible limitation of this study. Thus, future research with a larger sample size, broader age range and inclusion of more papilla determining factors are warranted to validate the results of the present study. Considering the growing attention paid to anterior esthetics by both patients and clinicians, a thorough understanding of the anatomic form of the interdental space will be a useful guide to achieve optimal soft-tissue esthetics.

CONCLUSION

Based on the above study, in relation to maxillary central incisors, all the interdental variables viz., distance from CP-PT, CP-pCEJ, BC-CP and BC-PT and IDW, have significant influences on the presence of interdental papillae, with distance from BC to CP to be the strongest determinant of central papilla presence. A thorough understanding of the morphology of the interdental tissues is mandatory, for a clinician before treatment planning for the maxillary anterior area, so as to enhance the esthetic outcome for the patient.