Periodontology – Furcation Defect

A furcation defect is a form of bone loss. This type of bone loss is typically a result of periodontal disease and it impacts the base of the root trunk of a tooth. This is the location where two or more roots connect. The specific extent and configuration of the defect are components which determine the diagnosis and planning for treatment.

A tooth which has a furcation defect, often includes a more diminished prognosis. This makes it more difficult to completely render the furcation area free from periodontal pathogens. Because of this, surgical periodontal treatment is often used to close the furcation defect or to allow improved access to the furcation defect for improved oral hygiene.

Root Trunk Length

The root trunk length is the distance between the cementoenamel junction (CEJ) and the furcation entrance. Because a deeper furcation entrance within the bone requires more bone loss before the furcation is exposed, the root trunk length plays a critical role in furcation defects.

For mandibular first molars, the mean root trunk length is 3 mm on the buccal aspect and 4 mm on the lingual aspect. Compared to the first molars, the root trunk length for mandibular second and third molars is typically the same or slightly greater. Although the roots can also be fused together.

The mean root trunk length is 3 to 4 mm on the buccal aspect for maxillary first molars. While the mean root trunk length is 4 to 5 mm on the mesial aspect, it is 5 to 6 mm on the distal aspect. Just as with the mandibular molars, the root trunk lengths for the maxillary second and third molars is typically the same or slightly longer compared to the first molars.

Classification of Furcation Defect

Because the assessment of periodontal disease is so important, there are various classification methods used to measure and document the severity of furcation involvement. Most of the indicators rely on horizontal measurements of attachment loss in the furcation.


In a clinical setting, a nabers probe is typically used to check for furcation involvement. Cone beam computerised technology (CBCT) has also been commonly used to detect furcation. Periapical and interproximal intraoral radiographs are helpful in the diagnoses and identification of the furcation.

A furcation defect can only occur on multi-rooted teeth. As a result, it is possible for the upper first premolar, maxillary and mandibular molars to be impacted. The upper premolars have just a single buccal and palatal root. Check furcation involvement from the mesial and the distal aspects of the tooth is also important.

Maxillary molars have three different roots, including a mesio-buccal root, disto-buccal root and a palatal root. Dentists will evaluate for a furcation from buccal, mesio-palatal and disto-palatal aspects. Mandibular molars have a single mesial and distal root and the involvement should be checked from both a buccal and lingual perfective.


The treatment for a furcation defect works to eliminate the bacteria from the exposed root surfaces. Treatment also aims to identify the anatomy of the tooth and better control plaque. Treatment plans for patients can vary based various factors but often include the following:

  • Grade I furcation: scaling, polishing, root surface debridement, or furcationplasty may be performed
  • Grade II furcation: treatment options may include furcationplasty, open debridement, tunnel preparation, root resection, extraction, guided tissue regeneration (GTR), or enamel matrix derivative
  • Grade III furcation: open debridement, tunnel preparation, root resection, GTR, or tooth extraction may be used for treatment
  • When there is extensive loss of attachment and alternative treatments are not realistic, tooth extraction may be considered.