Clinical Cases in Periodontics. Группа авторов

furcation invasion [4].

Figure 1.7.5 Interproximal open contact between teeth #13 and #14 (indicated by the red arrows) and vertical bone loss on #14 mesial.

Figure 1.7.6 Close root proximity between teeth #18 and #19.

In descending order of occurrence, CEPs are most commonly seen in mandibular second molars, maxillary second molars, mandibular first molars, and maxillary first molars. When CEPs are observed, they are usually seen on buccal aspects of molars [2] (Figure 1.7.7).

      Enamel pearls are ectopic globules of enamel and sometimes pulpal tissue that often adhere to the cementoenamel junction (CEJ). They are present in roughly 2.7% of the molars and are mostly found on maxillary third and second molars [5]. Moskow and Canut suggested that enamel pearls may also predispose a furcation to attachment loss [5] (Figure 1.7.8).

       Root Concavity

The furcal aspects of the roots frequently have concavities with a certain amount of depth (see Question B for details) that will encourage plaque accumulation and prevent proper instrumentation of furcation. Hence a root concavity may predispose the furcation to attachment loss (Figure 1.7.9).

Figure 1.7.7 Cervical enamel projection (indicated by the red arrow).

Figure 1.7.8 Enamel pearl (indicated by the red arrow).

Figure 1.7.9 Mesial and distal root concavities of maxillary first premolar.

       Size of Furcation Entrance

Approximately 80% of all furcation entrances are less than 1.0 mm in diameter, with about 60% less than 0.75 mm [6]. Because frequently used curettes and scalers have a face width of 0.75–1.10 mm, it is unlikely that effective removal of accretions at furcation can be achieved by using these instruments alone. Hence a small furcation entrance may predispose a furcation to attachment loss (Figure 1.7.10).

       Root Divergence and Root Fusion

The degree of root divergence in a multirooted tooth will influence the ability of the patient and dental professionals to control plaque level. Diverging roots allow easier instrumentation to the furcation area, whereas converging roots (e.g. root fusion) render access to the furcation area very difficult, resulting in poor plaque control and possible attachment loss (Figure 1.7.11).

Figure 1.7.10 The size of the Cavitron tip is too big to enter the furcated area, rendering scaling and root planing in this area very difficult.

Figure 1.7.11 The root divergence of #19 is more prominent than that of #17.

       Root Trunk Length

The length of root trunk affects attachment loss. The longer a given root trunk, the less likely a furcation will be predisposed to attachment loss. Teeth with taurodontism usually have apically displaced furcation and longer root trunk length [7] (Figure 1.7.12).

       Intermediate Bifurcation Ridge

      Intermediate bifurcation ridges are ridges spanning the bifurcation of mandibular molars in the mesiodistal direction. These ridges are present in 70–77% of the mandibular molars [8,9]. Just like other anatomic structures, the presence of an intermediate bifurcation ridge may hinder effective plaque control and root preparation by both the patient and dentist.

       Buccal Radicular Groove and Palato‐gingival Groove

Buccal radicular grooves and palato‐gingival grooves are developmental phenomena that affect mainly the maxillary anterior teeth [10,11]. These grooves run on the roots in the coronal‐apical direction. Due to their anatomy, the grooves frequently provide a plaque‐retentive area that is very difficult to instrument, making teeth with these developmental grooves more prone to attachment loss (Figure 1.7.13).

       Accessory Pulpal Canals

      Accessory pulpal canals are small endodontic canals branching off from the main root canal that may furnish a communication between the pulpal chamber and the periodontal ligament. These accessory canals are usually located near the root apex; however, they can also be found anywhere along the root, including the furcation area. There is a theory that some periodontal infections can originate from endodontic sources, traveling through accessory/lateral canals located in the furcation areas. In these cases there is periodontal involvement in the furcation, but the infection originated in the pulp. Although still controversial, it has been proposed that periodontal disease can result from pulpal infection. An endodontic infection may be present at the furcation area when the infection travels through accessory canals that end at the furca. Vertucci and Williams reported that accessory canals at furcations are present in 46% of human lower first molars [12]. Burch and Hulen observed accessory canals in 76% of maxillary and mandibular molars [9].

Figure 1.7.12 Long root trunk length (left) and short root trunk at #19 (right).

Figure 1.7.13 Palato‐gingival groove