The purpose of the present retrospective study was to evaluate the clinical and esthetic outcomes of the CAF with CTG in the treatment of post-orthodontic Miller Class III gingival recession of the lower incisors. The study included 15 patients who had undergone orthodontic treatment prior to development of recession, and for whom orthodontic correction was not feasible since the incisors were in malposition due to patient objection to corrective procedures or given the absence of lingual bone support as revealed by CBCT.
Most of the patients had completed the orthodontic treatment as young adults (between the ages of 14 and 18 years); however, accurate data could not be obtained regarding the exact starting time of the recession and the changes over time. All the patients reported fast progression of the recession, which caused them great concern and encouraged them to seek treatment urgently.
In this study, we classified gingival recessions using the Miller classification [21], probably the most commonly employed system for this purpose. Cairo and colleagues had suggested another classification system of gingival recessions, based on the interproximal clinical attachment level [27]. According to this classification, all the treated Miller Class III recessions in this study were RT2. However, in Cairo and colleagues’ classification, the malposition of the root is not considered a prognostic criterion, although it is a limiting factor for the amount of root coverage achieved at the buccal site after surgery [14]. This may be associated with the blood supply provided by interproximal soft tissue to the buccal flap/graft during the healing process. Therefore, in cases of post-orthodontic lower incisors recessions, the Miller classification, which takes into consideration the tooth position, is more appropriate.
Applying CAF combined with the CTG technique in Miller Class I or II buccal recession-type defects affecting the lower incisors, Zucchelli and colleagues reported up to 98% mean root coverage with 88% complete root coverage (CRC), provided the labial submucosal tissue was removed from the inner surface of the alveolar mucosa [24]. However, the scholarship on Miller Class III recessions is quite limited, mostly focused on the comparison of techniques or the evaluation of results obtained by new procedures.
In the present evaluation, mean root coverage for Miller Class III orthodontic-associated gingival recessions was found to be 83 ± 24%, while CRC was recorded in 48% of the sites at one-year compared to baseline measurements. RD, RW, and PD were significantly reduced; however, only RD at baseline had demonstrated interaction with ΔRD. Interestingly, no interaction was found for %RC, RW, and KTW, pointing to the RD as the main prognostic factor for the root coverage.
A case series study evaluating CAF with CTG for the treatment of Miller Class III gingival recessions in mandibular central incisors found 86% of mean root coverage with 43% of CRC [28]. Interestingly, an additional study by the same authors using CTG in combination with tunnel technique showed only 74% of mean root coverage and 14% of CRC for Miller Class III defects in mandibular incisors [29]. The investigators explained these differences by facts that minimal efforts were made in coronally advancing the flap with the tunnel technique and that most of the root coverage occurred through vascularization of the exposed graft.
A recent study comparing clinical outcomes of CTG with and without enamel matrix derivative in the treatment of Miller Class III defects on mandibular anterior teeth reported 78% and 73% mean root coverage and 22% and 18% of CRC, respectively, 12-months post-treatment [30]. Another recent study presented results of modified tunnel double papilla procedure for root coverage of post-orthodontic Miller Class III recessions with either the removal or not of the bonded lingual retainer (BLR) [14]. An improvement of 43% was found without the removal of the BLR, compared to 87% once the BLR was removed prior to surgery; however, only a small number of cases was evaluated in each group.
Regarding the mean root coverage (83 ± 24%), our results are in line with the findings from the aforementioned studies; however, CRC was slightly higher (48%) in our evaluation. Although CRC was reached in nearly half of the sites only and consequently, given a final mean root coverage esthetic score of 7.1 ± 2.6, this parameter may not be considered the most important treatment outcome; this is particularly true regarding non-esthetic areas such as anterior mandible, which is known to have worse results than other regions in the oral cavity (Harris, 1994; Nart et al., 2012). Evidently, a maintainable situation was provided in all cases, by creating an adequate zone of keratinized tissue (KTW12 months = 2.6 ± 0.8 mm), thus preventing frenum and muscle pull and allowing easier brushing in this area.
The mean esthetic score in the present study was 7.1 ± 2.6. In a recent meta-analysis, Cairo and colleagues compared esthetic results in different root coverage procedures [31]. The mean esthetic score in the different studies included in the meta-analysis for procedures with a CTG ranged between 7.5 and 9.45. Our results are somewhat lower than their results. However, we evaluated only Miller Class III recessions; since the RES is largely sensitive to the amount of root coverage [26] and Miller Class III recessions are considered highly challenging for CRC [20], the present esthetic score result is satisfactory.
An interesting finding of the present study is the statistically significant PD reduction (2.3 ± 1.3 to 1.0 ± 0.5), aligning with a previous report [24]. This favorable outcome may be due to the baseline PD measurements at the buccal aspect of lower incisors that are greater compared to the mean buccal PD reported in the literature for gingival recession [32]. A possible explanation involves the presence of deep bone dehiscence and a shallow vestibulum depth. In this clinical scenario, a buccal PD apical to the gingival recession forms more frequently, once a deep gingival defect reaches the vestibular fornix. The clinically significant PD and RD reductions, alongside the increase in KTW, represent a meaningful improvement in the periodontal conditions, which could be beneficial for the prognosis of the affected tooth and could justify the treatment of deep gingival recession affecting lower incisors even in the absence of the traditional esthetic or dentine hypersensitivity indications.
The major limitations of this study are its limited sample and lack of blinded examination of some of the clinical parameters. However, photographic examination by an independent evaluator and a high level of internal consistency partially compensate for these drawbacks.
Within the limitations of this study, our results confirm that combination of CAF and CTG may significantly improve post-orthodontic Miller Class III recessions of the mandibular incisors, even when correction of the tooth malposition is unattainable.