Prevalence of gingival recession and its correlation with gingival phenotype in mandibular incisors region of orthodontically treated female patients: A cross-sectional study.

BACKGROUND: Gingival recession is associated with dentin hypersensitivity, unesthetic appearance, and carious or noncarious cervical lesions. Orthodontic treatment, gingival thickness (GT), and keratinized tissue width (KTW) play roles in gingival recession etiology. The study is aimed to compare the prevalence of gingival recession in the mandibular incisor region of orthodontically-treated females with untreated controls, and to identify if there is any correlation among the GT, KTW, and gingival recession. SUBJECTS AND METHODS: A total of 150 Saudi females were enrolled in this study. They were categorized into the treatment group (n = 75) and control group (n = 75). Background characteristics and clinical periodontal parameters including the plaque index, gingival index, GT, KTW, gingival recession length (GRL), and gingival recession width (GRW) were recorded and compared between groups, and any associations were identified.
RESULTS: Among the orthodontically-treated females, 31 (41.33%) had at least one mandibular incisor with gingival recession, in contrast to 18 (24%) of the controls. Pearson's correlation analysis indicated a significant positive correlation between the GT and KTW and between the GRL and GRW (P < 0.001). In addition, a significant negative correlation was observed between the KTW and GRL and between the KTW and GRW (P < 0.001). However, no significant correlation was found between the GT and GRL or between the GT and GRW.
CONCLUSIONS: Our findings indicated that orthodontic treatment is a predisposing factor for the development or progression of gingival recession, particularly in females with a narrow KTW. Copyright:

INTRODUCTION

Periodontal disease is a global public health issue, and one of the most common concerns related to this condition is the gingival recession. The term “gingival recession” refers to the oral exposure of the root surface owing to the apical shift of the gingival margin away from the cementoenamel junction (CEJ).[1] It is a common condition that poses some difficulties for dental professionals because of the uncertain etiology, although various predisposing factors, including mechanical trauma, inflammation in the periodontal tissue, and bone dehiscence, have been found to play a role in the development of gingival recession.[12]

A further possible etiological factor for gingival recession is orthodontic treatment.[2] Data from several studies suggest that orthodontic treatment could promote gingival recession.[345] Renkema et al. found that young adults with a history of orthodontic treatment were at approximately 4.5-fold greater risk of recession than untreated controls.[4] The prevalence of gingival recession in orthodontically-treated individuals is 5%–12%, but has been reported to reach 47% in longitudinal studies.[2] It is reported that the mandibular incisors are most vulnerable to gingival recession.[67] This could be attributed to the fact that these teeth typically undergo significant anterior displacement during orthodontic treatment, resulting in the loss of alveolar bone, which is generally thin.[78] Previous research has observed alveolar bone dehiscences in patients with a narrow alveolar process after proclination of the mandibular incisors, which lead to the development of gingival recession.[4]

It has also been suggested that gingival recession is affected by the gingival phenotype, which encompasses the gingival thickness (GT) and keratinized tissue width (KTW).[9] The alveolar bone thickness was found to be directly proportional to the GT.[10] Thus, individuals with thin gingiva and narrow keratinized tissue have a higher tendency to develop recession than those with thick gingiva and wide keratinized tissue.[911] In addition, it is well-known that genetic traits precipitate variation in the gingival phenotype among different populations.[9] The reported prevalence of a thin gingival phenotype was 47%–52% in the Saudi populations.[1213]

Several studies suggest that the GT and KTW are positively correlated with one another in the maxillary anterior region,[14151617] but the literature is lacking regarding data on other regions. To our knowledge, few studies have investigated the correlations among the GT, KTW, and gingival recession in the mandibular incisor region, particularly regarding orthodontic treatment.

Therefore, the primary aim of this study was to determine and compare the prevalence of gingival recession in the mandibular incisor region in orthodontically-treated females and untreated controls. Second, we aimed to identify any correlations among the GT, KTW, and gingival recession.

SUBJECTS AND METHODS

This cross-sectional study was performed at the dental clinics of our institution between November 2019 and February 2020. The convenience sampling technique was used in this study, all patients who visited the dental screening clinic at Qassim University during the study period were screened by a single investigator, those who meet the eligibility criteria were included in this study. Ethical approval from the university was obtained before commencing the study (EA/6038/2019). All eligible participants received a thorough explanation of the study and provided written informed consent before participation.

The study sample consisted of 150 Saudi females, divided into two groups: The treatment group, consisting of 75 individuals with a history of orthodontic treatment; and the control group, consisting of 75 individuals with no history of any orthodontic treatment. The individuals in the treatment group were enrolled using the following criteria: Individuals treated with full fixed appliances, evaluated ≥1 year after de-bonding, without orthodontic re-treatment. For both groups, individuals with good oral hygiene and aged 17–36 years were included. Individuals who had systemic diseases, were pregnant, received any antibiotics within the past 6 months, had a high attachment of the lower labial frenum, and had a history of any periodontal surgical treatment or any restorative or prosthetic treatment in the area of the mandibular incisors were excluded.

The clinical periodontal parameters were:

Silness and Loe plaque index (PI) and Loe and Silness gingival index (GI),[1819] which were recorded from Ramfjord teeth (teeth 16, 21, 24, 36, 41, and 44) in all study participants. In cases in which one of the premolars was missing, it was substituted by teeth 25 and 45, as suggested by Fleiss et al.[20]

GT, which was measured using a 15 mm endodontic spreader placed in the centre of a silicone stopper and inserted perpendicularly from the vestibular midpoint through the soft tissues until a hard surface was felt [Figure 1]. The penetration depth between the silicone stopper and the spreader tip was measured using a digital caliper with 0.01 mm sensitivity [Figure 2]. Lidocaine spray was used if required to alleviate pain. The GT of each tooth was determined by the mean of the values from two regions: 1 mm apical to the gingival margin, and 1 mm coronal to the mucogingival junction. A GT of <1 mm was classified as a thin gingival phenotype, and a GT of >1 mm as a thick phenotype[2]

Figure 1

Gingival thickness measurement in the mandibular incisors region using a 15 mm endodontic spreader with silicone stopper placed perpendicular to the soft tissue

Figure 2

Gingival thickness was calculated by measuring the penetration depth between the silicone stopper and the spreader tip using a digital caliper with 0.01 mm sensitivity

KTW, which was measured from the gingival margin to the mucogingival junction at the mid-buccal point of the tooth

Gingival recession length (GRL), which was measured from the CEJ to the gingival margin of the exposed root surface

Gingival recession width (GRW), which was measured in a mesiodistal direction 1 mm apical to the CEJ of the exposed root surface.

For measurement of the KTW, GRL, and GRW, a University of North Carolina-15 periodontal probe with a silicone stopper was used, and the distance between the tip of the probe and the silicon stopper was measured using a digital caliper.

All clinical measurements were performed by a single examiner to minimize bias. In addition, ten individuals from each group were re-examined by the same examiner after 1–2 weeks to check the intraexaminer reliability. The Intraclass correlation coefficients for PI, GI, KTW, GT, GRL, and GRW were all >0.92, indicating excellent reliability.

SPSS version 21 software (IBM Corp, Armonk, NY, USA) was used for all statistical analyses. The data were analyzed using individuals and teeth as units. The Chi-square test was used to compare proportions and a t-test was used to compare mean values. Pearson's correlation coefficient was used to assess associations among the parameters. P < 0.05 was considered statistically significant.

RESULTS

The mean age was 27.11 ± 4.68 years and 25.89 ± 4.46 years for the orthodontically-treated group and untreated group, respectively, and there was no significant difference in age between groups (P = 0.106). The PI was significantly higher in the untreated than the treated group (P < 0.05). However, the GI did not significantly differ between groups [Table 1].

Table 1

Age and oral hygiene parameters according to study groups

Study group	n	Age	PI	GI
Treated group	75	27.11±4.675	1.151±0.543	0.280±0.279
Untreated group	75	25.89±4.456	1.3432±0.597	0.3063±0.274
P		0.106	0.042*	0.570

Results expressed as: Mean±SD. *Significant at the 0.05 level. n – Number of participants; PI – Plaque index; GI – Gingival index; SD – Standard deviation; P – Probability value

Among the orthodontically-treated females, 31 (41.33%) had at least one mandibular incisor with gingival recession, in contrast to 18 (24%) of the controls. This difference was significant (P < 0.05). The thin phenotype was predominant in both groups [Table 2]. The gingival parameters differed between the groups, but not significantly [Table 3].

Table 2

Gingival parameters distribution in mandibular incisors according to study groups

Study group	n	Gingival phenotype		Gingival recession
		Thin	Thick	With recession	No recession
Treated group	75	62 (82.67)	13 (17.33)	31 (41.33)	44 (58.67)
Untreated group	75	56 (74.67)	19 (25.33)	18 (24.00)	57 (76.00)
P	0.23	0.024*

Results expressed as: n (%). *Significant at the 0.05 level. n – Number of participants; P – Probability value

Table 3

Comparative analysis of mean values of gingival parameters according to study groups

Study group	n	GT	n	KTW	n	GRL	n	GRW
Treated group	75	0.844±0.193	75	4.036±1.028	31	1.332±0.844	31	1.271±0.555
Untreated group	75	0.882±0.213	75	4.296±0.969	18	1.298±1.115	18	1.173±0.620
P		0.263		0.112		0.906		0.570

Results expressed as: Mean±SD. n – Number of teeth; GT – Gingival thickness; KTW – Keratinized tissue width; GRL – Gingival recession length; GRW – Gingival recession width; SD – Standard deviation; P – Probability value

Gingival recession was found in 92 (30.67%) of 300 teeth in the treated group, but only 45 (15%) of 300 teeth in the untreated group. The prevalence of gingival recession was significantly higher in central incisors than other teeth (P < 0.001); 54 (58.70%) and 29 (64.44%) of the teeth with recession were central incisors in the treated and untreated groups, respectively [Table 4]. For teeth with gingival recession, there was no significant difference regarding the GT, KTW, and GRL between the central and lateral incisors. Only the GTW was significantly higher in the lateral incisors than other teeth (P < 0.001) [Table 5].

Table 4

Gingival recession prevalence in mandibular incisors according to tooth type

Tooth type	Study group				P
	n	Treated group	n	Untreated group
42	75	17 (22.7)	75	7 (9.3)	0.026*
41	75	27 (36)	75	15 (20)	0.029*
31	75	27 (36)	75	14 (18.7)	0.017*
32	75	21 (28)	75	9 (12)	0.014*
Total	300	92 (30.67)	300	45 (15.00)	0.000**

Results expressed as: n (%). *Significant at the 0.05 level; **Significant at the 0.01 level. n – Number of teeth; P – Probability value

Table 5

Comparative analysis of mean values of gingival parameters in mandibular incisors with gingival recession according to tooth type

Tooth type	n	GT	KTW	GRL	GRW
CI	83	0.827±0.182	3.270±0.929	1.900±0.882	1.642±0.401
LI	54	0.817±0.157	3.502±0.783	1.867±0.916	1.957±0.410
Total	137
P		0.746	0.132	0.834	0.000*

Results expressed as: Mean±SD. *Significant at the 0.05 level. n – Number of teeth; CI – Central incisors; LI – Lateral incisors; GT – Gingival thickness; KTW – Keratinized tissue width; GRL – Gingival recession length; GRW – Gingival recession width; SD – Standard deviation; P – Probability value

The results of the correlational analysis of age and gingival parameters are provided in Table 6. Pearson's correlation analysis indicated a significant positive correlation between the GT and KTW and between the GRL and GRW (P < 0.001). In addition, a significant negative correlation was observed between the KTW and GRL and between the KTW and GRW (P < 0.001). Moreover, there was a significant positive correlation between age and the GRL (P < 0.001) and between age and the GRW (P < 0.05).

Table 6

Correlation analysis of age and gingival parameters in mandibular incisors of study groups

Variable	Age	KTW	GT	GRL	GRW
Age	-	0.069 (−0.149)	0.634 (0.039)	0.006** (0.223)	0.012* (0.205)
KTW	0.069 (−0.149)	-	0.000** (0.584)	0.000** (−0.396)	0.000** (−0.390)
GT	0.634 (0.039)	0.000** (0.584)	-	0.153 (−0.117)	0.290 (−0.087)
GRL	0.006** (0.223)	0.000** (−0.396)	0.153 (−0.117)	-	0.000** (0.912)
GRW	0.012* (0.205)	0.000** (−0.390)	0.290 (−0.087)	0.000** (0.912)	-

Results expressed as: Significance (Pearson correlation). *Correlation is significant at the 0.05 level; **Correlation is significant at the 0.01 level. GT – Gingival thickness; KTW – Keratinized tissue width; GRL – Gingival recession length; GRW – Gingival recession width

However, no significant correlation was found between the GT and GRL or between the GT and GRW.

DISCUSSION

The growing public interest in oral health increases the demand for orthodontic treatment, which can improve both function and appearance. However, like many other treatments, orthodontic treatment comes with adverse effects. We focused in this study on female patients, as they tend to have more self-interest in orthodontic treatment. It was suggested that orthodontic treatment may lead to gingival recession, which in turn, will result in dentin hypersensitivity, unesthetic appearance, and carious or noncarious cervical lesions.[2]

This study is the first of its kind in Saudi Arabia, wherein the correlation between the gingival phenotype with a history of orthodontic treatment and gingival recession is explored.

When the prevalence of gingival recession was compared between the groups, the prevalence was higher among treated (41.33%) than untreated females (24%) [Figure 3]. These results reflect those of Renkema et al. who also found a higher recession prevalence in orthodontic cases than controls.[4] A positive association between prior orthodontic treatment and the occurrence of gingival recession was reported.[5] In addition, Gebistorf et al. investigated the long-term development of gingival recession in 88 orthodontically-treated individuals and found an increased rate of recession during the treatment with a further increase after 10–15 years' follow-up.[3] Nevertheless, Morris et al. reported that only a minimal degree of gingival recession was present immediately after orthodontic treatment, and the increased recession observed after 2 years was not severe.[21] Another study also reported that the gingival recession of mandibular incisors after orthodontic treatment is minor in prevalence and severity.[22] One of the potential ways, in which orthodontic treatment can impact gingival recession is by the plaque accumulation around the appliances and the subsequent inflammation. Orthodontic patients must maintain good oral hygiene to avoid such problems. Toothbrush trauma could also cause pressure atrophy of the alveolar bone and gingiva.[217] Moreover, orthodontic tooth movement on the expenses of the labial or lingual alveolar plate could induce bone dehiscence, which acts as a predisposing factor of gingival recession.[14] Regardless, it has been reported that orthodontic tooth movement should not be considered as a primary cause of gingival recession,[1] since the buccolingual tooth position is affected by the marginal bone thickness and gingival phenotype.[123] Kim and Neiva showed that individuals with a thin periodontal phenotype have a higher risk of developing bone dehiscence and gingival recession during orthodontic treatment.[23]

Figure 3

Gingival recession related to the mandibular incisors of a 29-year-old orthodontically-treated female (a) frontal view (b) right-side view

Many methods have been introduced for measuring the GT, such as cone beam computed tomography (CBCT), ultrasonic devices, transgingival probing, and probe transparency. In a recent study, ultrasonic devices and transgingival probing were demonstrated to be highly reproducible.[24] Nevertheless, it has been reported that ultrasonic devices were unable to detect small changes.[2526] Hence, we used the transgingival probing technique, and to overcome the transient local volume increase of local anesthesia we used a topical anaesthetic as an alternative in the required cases. Most of the study participants expressed a thin gingival phenotype as anticipated since the gingival phenotype was judged according to the mandibular incisors, which were reported to have the thinnest GT.[27] Another possible reason is that all of the participants were female. Joshi et al. compared the GT in 400 males and 400 females, and noticed that female participants had thinner GTs than males.[10] Zawawi and Al-Zahrani also demonstrated that females were more likely to have a thin GT.[13] However, other studies reported no significant difference in GT between sexes.[151727]

Consistent with our study results, Morris et al. observed that the prevalence of recession was higher on the central than the lateral incisors.[21] The development of gingival recession in our sample does not seem to be associated with differences in the GT and KTW since no significant difference was found between the central and laterals incisors.

Several reports have found a correlation between the GT and KTW.[14151617] A systematic review of the literature regarding the characteristics of periodontal biotypes, their dimensions, and associations concluded that there were consistent positive associations among the GT, KTW, and bone morpho-type.[16] Egreja et al. examined the correlation between the GT (measured by trans-gingival probing) and KTW in the maxillary anterior teeth of 60 patients, and found a positive correlation between the GT and KTW in all examined teeth: Central incisor (0.49), lateral incisor (0.37), and canine (0.40).[17] Shah et al. also observed a significant correlation between the GT and KTW for the central incisor (0.35), lateral incisor (0.35), and canine (0.32).[15] However, the literature was lacking regarding correlations of the GT and KTW in the mandibular incisors.[28] Shao et al. evaluated the accuracy of different methods for GT measurement and found a positive correlation between the KTW and GT measured by CBCT scanning (0.31) and GT measured by transgingival probing (0.38).[28] This is comparable to our results, which indicated a positive correlation between the GT and KTW (0.58).

Maroso et al. investigated the correlation between the GT and gingival recession in healthy individuals without a history of periodontitis, and found that the GT was inversely correlated with gingival recession.[29] Our results also indicated a negative relationship, but without any significance. Shah et al. evaluated the anterior maxillary teeth of 400 individuals and found that 66 (16.50%) presented with gingival recession, 32 (48.48%) presented with a thick GT, and 34 (51.51%) had a thin GT; these authors were unable to report any correlation between the GT and gingival recession.[15] They attributed this to a statistical error that could have occurred due to the abrupt transformation of a thin GT at 0.99 mm to a thick GT at 1.00 mm, and the young age of the participants (20–35 years in Shah et al., and 17–36 years in our study). Although their small proportion of individuals with gingival recession (16.50%) was also considered a contributing factor to the lack of correlation,[15] in the present study, no significant correlation was found with an almost doubled proportion of patients with recession (32.67%). However, a significantly negative correlation between the KTW and gingival recession was demonstrated, and this finding was also reported in many previous studies.[21623] A recent systematic review concluded that a reduced KTW could lead to the development or progression of gingival recession and inflammation.[23] The data from this study demonstrated that the risk of recession was significantly associated with age. This finding is in line with that of Pernet et al., who reported a similar finding and attributed this relationship to the progression of periodontal disease, microbial action, and aggressive brushing techniques.[30]

This study is limited. Some confounding factors that may have an impact on gingival recession, such as brushing technique, buccolingual tooth position, and level of crowding, have not been considered in this study. Further longitudinal studies, which take these factors into account, and include different age groups and both sexes, should be considered.

CONCLUSIONS

Orthodontic treatment is considered to be a predisposing factor for the development or progression of gingival recession, particularly in females with a narrow KTW. The GT is positively correlated with the KTW in the mandibular incisor region. The results of this study should be considered when planning comprehensive orthodontic treatment, as careful assessment of the periodontal tissue is important when designing an appropriate treatment plan to ensure that tooth movement occurs within the envelope of the periodontium.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.