Immediate implant at a three-rooted mandibular molar: A case report with 7-year follow-up

The prevalence of short roots, fused molar roots, and three-rooted mandibular molars is relatively high in Asian populations.¹ These anatomical variations may lead to unfavorable periodontal prognosis, increasing the likelihood of tooth extraction and implant therapy at these sites. Furthermore, these unique anatomical features may result in reduced available bone and decreased primary stability for immediately placed implants. Specifically, Cone beam computed tomography (CBCT) is crucial for evaluating factors such as the proximity of the extraction site to the maxillary sinus and inferior alveolar canal, socket morphology, the availability of sufficient interradicular septal bone, and the presence of lingual concavities.² All factors should be carefully considered prior to immediate implant placement. Long-term studies assessing the clinical outcomes of immediate molar implants in Asian populations with unique root morphologies are scarce. This long-term case report aims to evaluate the clinical and radiographic outcomes of an immediate implant placed in a three-rooted mandibular molar of a Taiwanese patient.

A 52-year-old male patient presented with a root fracture in a three-rooted mandibular first molar, rendering the tooth non-restorable and unsuitable for endodontic treatment (Fig. 1A). CBCT was used to evaluate factors such as special root morphologies, the presence of lingual concavities, proximity to the inferior alveolar canal, socket morphology and availability of sufficient interradicular septal bone. After the careful extraction of the tooth, a type B socket was identified (Fig. 1B).³ A pilot drill was used to access the center of the residual root septum, followed by the preparation of the implant bed. Subsequently, a cylindrical screw-type implant was immediately placed. The socket defect was then filled with alloplastic graft material and covered with a collagen membrane. The interdental papillae were sutured with 4-0 polytetrafluoroethylene sutures for wound stabilization (Fig. 1C). Six months later, the final crown was delivered. Clinical and radiographic evaluations at the 7-year follow-up showed healthy mucosa with minimal tissue recession and marginal bone loss (Fig. 1D).

Figure 1.

Clinical photographs and radiographs of our patient. (A) A 52-year-old male patient presented with a root fracture in a three-rooted mandibular first molar, rendering the tooth non-restorable and unsuitable for endodontic treatment. Cone beam computed tomography was used to evaluate factors such as special root morphologies, the presence of lingual concavities, proximity to the inferior alveolar canal, socket morphology and availability of sufficient interradicular septal bone. (B) After the careful extraction of the tooth, a type B socket was identified [4]. A pilot drill was used to access the center of the residual root septum, followed by the preparation of the implant bed. Subsequently, a cylindrical screw-type implant was immediately placed. The socket defect was then filled with alloplastic graft material and covered with a collagen membrane. (C) The interdental papillae were sutured with 4-0 polytetrafluoroethylene sutures for wound stabilization. (D) Six months later, the final crown was delivered. Clinical and radiographic evaluations at the 7-year follow-up showed healthy mucosa with minimal tissue recession and marginal bone loss.

This case report showed good clinical and radiographical implant outcome with no biological and technical complications. A higher prevalence of three-rooted mandibular first molars was observed in the Taiwanese population (approximately 20%–25%) compared to Caucasian populations (around 4%).¹ In a systematic review and meta-analysis of Caucasian populations, Ragucci et al. reported a mean survival rate of 96.6 % for immediate implants after one year of follow-up, with a mean marginal bone loss of 1.29 ± 0.24 mm.⁴ In a cross-sectional analysis conducted 2–10 years post-implantation, Parvini et al. found that 4.2% of patients experienced peri-implantitis, while 6 % of implants exhibited 1 mm of mucosal recession.⁵ Impact of three-rooted mandibular molars on clinical outcome and peri-implantitis in immediate implant placement has not been previously reported. Although the molar extraction site in this study displayed unique root anatomy and a type B socket, neither was associated with an increased risk of marginal bone loss and peri-implantitis. This case report is the first to confirm that immediate molar implant placement is an effective and predictable treatment modality for a Taiwanese patient with unique root morphology. Although a three-rooted molar socket may pose additional challenges for immediate implant placement, meticulous planning and the application of a well-structured treatment protocol can lead to successful long-term outcomes.

Declaration of competing interest

The authors have no conflicts of interest relevant to this article.