Background

The subepithelial connective tissue graft (SCTG) provides the best outcomes1 and long-term stability2 for root coverage. Both early1, 3, 4 (days to weeks) and late5-11 (months to years) SCTG complications have been reported. Early complications include pain, discomfort, swelling, infection, and bleeding.1, 3, 4 Late complications include cyst6, 7 and exostosis9 formation, and root resorption.10, 11 This report documents a successful SCTG presenting with successive epithelial origin complications, namely epithelial cell discharge and epidermal inclusion cyst (EIC), and describes their timing, diagnosis, and management.

Clinical Presentation

In July 2018, a 35-year-old White male, non-smoker, was referred to the Graduate Periodontology Clinic at The Ohio State University for buccal gingival recession on teeth #27 and #30 (Fig. 1a). Verbal informed consent was obtained from the patient to report the case. Chief complaint was sensitivity to cold. His medical history was unremarkable except for extensive acne treatment as a teenager. Examination revealed two localized recession defects, both 3-mm deep and lacking attached gingiva (Miller Class II), on #27 and on #30 (mesial root), with normal probing depths and good oral hygiene. The patient had orthodontic treatment history, root prominences, and buccal dehiscences, which could have contributed to recession development. Aiming for root coverage, envelope flap+SCTG was recommended to and accepted by the patient. Tooth #27 was treated in August 2018. Following local anesthesia and root surface mechanical instrumentation, a full-thickness envelope flap was elevated and the harvested SCTG (parallel incision technique) was de-epithelialized and adapted to the site (Fig. 1b). The overlying flap was coronally positioned, leaving the coronal SCTG portion exposed. The flap and graft were sutured separately with absorbable sutures and the surgery was completed uneventfully (Fig. 1c). Analgesics and antimicrobial mouth rinse were prescribed and postoperative instructions were given.

Initial presentation and root coverage procedure. 1a Note recession defect on canine (#27) and on first molar (#30). 1b Harvested graft applied over defect. 1c Surgery completed.

At 2 weeks, healing was within normal limits (WNL) and sutures were removed. The patient reported limited pain and no concerns. At 4 weeks, healing continued uneventfully (Fig. 2a). At 8 weeks, the patient reported mild discomfort at the recipient site; clinical presentation was WNL. At 4 months, complete root coverage had been obtained and the patient reported persistent discomfort, slowly increasing in intensity. On the distal buccal gingiva of #27 a diffuse, minimally compressible, swelling was evident. Gentle pressure produced a semi-solid white discharge (Fig. 2b), which was evaluated using a Papanicolaou-stained cytologic smear. Normal epithelial cells were observed.

Postoperative course and epithelial cell discharge. 2a Presentation at 4 weeks postoperatively. Note root coverage and healing within normal limits. 2b Presentation at 4 months postoperatively. Arrow points to semi-solid discharge elicited by application of pressure. 2c Presentation at 6 months postoperatively. Arrow points to semi-solid discharge elicited by application of pressure.

Case Management

The patient was informed of the benign and possible self-limiting nature of this complication.8 The swelling was less obvious at 5 months and 6 months postoperatively, and pressure again elicited white discharge (Fig. 2c).

At 1 year, the swelling was more prominent, fluctuant, and had enlarged, measuring 5 mm x 4 mm (Fig. 3a), with constant discomfort reported. With cyst as a working diagnosis, an excisional biopsy was performed in October 2019. The biopsy wound was electrocauterized for hemostasis and sutured with absorbable sutures. Histologic evaluation revealed a cyst lined by variably thick stratified squamous epithelium exhibiting abundant luminal parakeratin production (Fig. 4). A diagnosis of EIC was rendered.

Epidermal inclusion cyst and final follow-up. 3a Presentation at 1-year postoperatively. Arrow points to enlarged swelling which was fluctuant. 3b Presentation 4 weeks after biopsy. Healing within normal limits. 3c Presentation 8 months after biopsy (20 months after root coverage procedure). Note complete root coverage on tooth #27 and tooth #30.

Histopathology of lesional tissue. 4a The luminal cystic cavity and the variable thickness of the lining stratified squamous epithelium are apparent; the black rectangle identifies the area magnified in panel 4b. 4b Note the abundant luminal parakeratin present. (Hematoxylin and eosin; original magnification = 4a, x40; 4b, x100)

Clinical Outcomes

Uneventful, asymptomatic healing was evident at all postoperative visits (1, 2, 4, and 8 weeks [Fig. 3b]). At last follow-up, 8 months after biopsy, a firm cicatrix was evident at the site (Fig. 3c); the patient remained symptom-free.

Discussion

Among the many treatment modalities available for root coverage, e.g., flap alone, flap combined with SCTG, allografts, or biologics, the choice of envelope flap plus SCTG for this case was based on site characteristics, the predictability of clinical outcomes,1 and the very low incidence of long-term complications (Table 1).5-11 The present report is the first to document the clinical occurrence of sequential SCTG late complications of epithelial origin, namely epithelial cell discharge, manifesting at 4 months postoperatively, and EIC formation, evident 8 months later. Complete removal of the cyst was confirmed histologically, and no recurrence has been observed 8 months post-biopsy.

TABLE 1. Late complications following SCTG for root coverage Complication Report Sex Age (y) Site Time (months) Preceding Procedure Management Graft Deepithelialized Cul-de-sac Wei and Geivelis, 20035 F 40 Mandibular, Incisor 9 SCTG, Gingivoplasty Incision, Gingivoplasty, Free SCTG Y Cyst Breault et al., 19976 M 76 Mandible, Incisor 15 SCTG Excision Y Harris, 20027 F 27 Mandible, Canine 13 SCTG Punch biopsy, Ginigivoplasty Y Present report M 35 Mandible, Canine 12 SCTG Excision Y Epithelial cell discharge Present report M 35 Mandible, Canine 4 SCTG Observation Y Parashis and Tatakis, 20078 F 19 Mandibular, Incisor 4 SCTG Self limiting Y Exostosis Corsair et al., 20019 F 29 Maxilla, Premolar/Canine 60 SCTG Osteoplasty, Gingivoplasty Not reported Root resorption Hokett et al., 200210 M 37 Maxilla, Canine 12 SCTG Access flap, Root planing Not reported Carnio et al., 200311 F 57 Maxilla, Incisor 24 SCTG Extraction Y

Location and timing of the discharge are consistent with the previous report of epithelial cell discharge.8 EIC formation timing is also consistent with previous reports, where most cysts emerged after about a year6, 7 and only rarely appeared early.12 All cases3, 6, 12 were limited to anterior teeth, mainly mandibular.

The exact cause of epithelial proliferation and subsequent cyst development is unclear, however, epithelial tissue remnants on the graft possibly caused these complications. Herein, the graft was harvested by double incision technique and de-epithelialized with a blade. Harris13 reported that residual epithelium was evident microscopically in 80% of SCTGs thus harvested, despite de-epithelialization. When SCTGs, combined with coronally positioned flap, were biopsied at 2 months postoperatively, 12.5% (two of 16) were found to have epithelial inclusions in the deep portion of the connective tissue.14 In the latter study, SCTGs were harvested in the form of free gingival grafts and de-epithelialized extraorally.14 Collectively, these findings suggest that the likelihood of epithelial remnants on SCTGs may vary by harvesting technique.13, 14

In the oral cavity, the proposed EIC formation mechanisms15 are traumatic implantation of epithelium or proliferation of ectodermal remnants during embryogenesis. In the present case, the former mechanism (surgical trauma with residual epithelium implanted13, 14) plausibly explains the EIC pathogenesis. It is also reasonable to hypothesize that the epithelial cell discharge observed at 4 months represented an incipient stage in EIC formation, suggesting that the two complications may be related. Regardless, it appears that such epithelial complications do not jeopardize the root coverage outcome.7, 8, 12, 14

Among the few reported late complications following SCTG use for root coverage, most are of epithelial origin (Table 1). Two cases of epithelial cell discharge,8 including the present report, occurred at 4 months postoperatively. Cul-de-sac was reported at 9 months postoperatively.5 Most of the reported cysts occurred around 1 year postoperatively,6, 7 except one early case.12 SCTG late complications of connective tissue origin are even scarcer and include two root resorption cases,10, 11 incidental findings identified 1 to 2 years postoperatively, and an exostosis report,9 developing 5 years postoperatively.

Conclusion

This report highlights cyst formation as a rare yet possible SCTG complication and emphasizes the importance of an excisional biopsy as the means to obtain a definitive diagnosis and appropriately manage this complication.

Summary Why is this case new information? ■

To the best of our knowledge, this report is the first to describe a case of successful SCTG presenting with sequential epithelial origin late postoperative complications, i.e., epithelial cell discharge and subsequent epidermal inclusion cyst.

What are the keys to successful management of this case? What are the primary limitations to success in this case? Acknowledgment

The authors report no conflicts of interest related to this case report.

Author Contributions

All authors contributed to patient care, providing either diagnostic or both diagnostic and therapeutic services. Case documentation was provided by Ying Wang, Caroline Bissonnette, and Christopher Brett. The case report was drafted, prepared, and revised by Ying Wang; critically revised by Caroline Bissonnette and Kristin K. McNamara; and edited, revised, and finalized by Dimitris N. Tatakis. All authors approved the final version of the manuscript.

REFERENCES

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