26 January 2021

---

Root sectional therapy: survival rates and outcomes

Giulia Palandrani

---

Molars with intra-radicular horizontal and vertical bone destruction tend to respond less favorably to routine periodontal treatment than single-rooted teeth. Class II and III furcation involvement have an increased risk for tooth loss in molars with or without supportive periodontal maintenance therapy.

Root resection has been considered a viable treatment for multi-rooted teeth with furcation defects before considering tooth extraction and subsequently, the need to prosthetically replace the missing teeth.

Classic literature has reported predictable long-term out-comes for teeth undergoing root resection when performed by clinicians with expertise in clinical endodontics, prosthodontics, and periodontics. The aim of this article was to determine survival rates of root resection therapy and reasons for failure in an academic setting with less experienced providers.

Materials and methods
The study population includes patients who had undergone root resection therapy  at the University of Michigan, School of Dentistry, Graduate Periodontics Clinic, between January 1990 and September 2017, and maintained a follow up at least 12 months.

Dental history and site-specific factors were recorded, including history of periodontal disease, presence of bleeding on probing (BOP), presence of exudate, radiographic bone loss (BL), PD, and parafunctional habits. Furthermore, relevant data pertaining to the root-resected tooth such as location in the oral cavity, specific resected root, purpose of the surgical procedure, reasons for tooth extraction (caries/restorative, fracture, endodontic, periodontal disease), history of endodontic treatment (≥6 months prior, < 6 months before/in concomitance with, or after the root resection procedure), type of final restoration (e.g., composite, porcelain-fused metal crown, tooth-supported fixed partial prosthesis), presence/absence of post in non-resected roots, presence/absence of adjacent teeth and type of opposing dentition (e.g., natural intact tooth, tooth-supported single crown, implant-retained restoration) were obtained. 

Results
A total of 85 patients, composed of 49 males (57.6%) and 36 females (42.4%) with an overall mean age of 62.5 ± 10.8 years and a mean follow-up of 5 ± 4.3 years (range: 1 to 16.8 years), were included. 

The mean survival time of root-resected teeth was 109.9 months (9.1 years). Only a total of 47 teeth remained as part of the dentition (55.3%), while 38  (44.7%) failed due to fracture (39.5%), caries (26.3%), periodontal disease (23.7%), endodontic reason (2.4%) and in only two cases the cause of extraction could not be determined (2.4%). 

A significant decrease in the survival rates is shown during the first 4 years after root resection therapy  (n = 31; 81.5% of all failures). Overall, high failure rate was observed for root-resected teeth due to endodontic reasons or vertical fracture with a three-fold (210%) and nine-fold (840%) increased risk of failure than those resected due to a periodontal etiology (P < 0.01). 

A higher tendency of failure was observed when the antagonist was a dental implant; four out of seven teeth failed (P = 0.062). The reason for failure was due to a fracture (100%)

Maxillary first molars exhibited greater failure rates then the rest of the dentition (P=0.007). Furthermore the survival rate of the 54 maxillary first molars was lower when the mesio-buccal root was extracted (P = 0.081).

Discussion
In the present study, the most frequent cause of failure as root resection was root fracture (39.5%). The considerably high failure rate caused by fracture could be explained by the fact that nearly the entire sample comprised non-splinted teeth (the vast majority (85.9%) received a single crown or a simple restoration). It has been previously highlighted that splinting a resected tooth to neighboring teeth confers a protective effect toward its survival. 

Periodontal disease was the other most frequent causes of failure, with 23% of the teeth having been extracted due to this reason. Interestingly almost half (45.5%) of the teeth that received a root resection for a periodontal reason failed due to periodontitis. Hence, this highlights the importance of creating a cleanable environment for periodontal maintenance, providing constant oral hygiene instruction, and encouraging patient compliance when performing root resection. 

Conclusions
Within the imitations of this study, root resection therapy remains a treatment solution for molars with furcation defects. In an academic setting with less experienced clinicians, >50% of teeth remained functional after 9 years of root resection therapy. Root resection should be considered a valid option before implant therapy, especially in patients with identifiable risk factors (e.g., heavy smokers) associated with peri- implant diseases.