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Defined as an apical extension of enamel usually toward a furcation,¹ enamel projections (also known as cervical enamel projections [CEPs]) are common anatomical variations where a definitive projection of enamel extends into the furcation area, preventing true attachment of periodontal ligament (PDL) fibers upon the root surface⁷ (Fig 5-1).

Fig 5-1 Classification of cervical enamel projections.

Early observations in dental anatomy described how the enamel dips into the furcation area of multirooted teeth in a tongue-like fashion.^42–48 A landmark article by Masters and Hoskins examined extracted teeth with CEPs and suggested a grading system to determine the severity of these projections (Box 5-2).⁷ The authors reported the prevalence of CEPs in mandibular and maxillary molars as 28.6% and 17%, respectively. In addition, clinical observations revealed that 90% of isolated furcation involvements were associated with CEPs and mainly affected buccal furcation entrances.⁷

BOX 5-2 Grading system for cervical enamel projections by Masters and Hoskins⁷

Grade IGrade IIGrade III

A distinct change in CEJ attitude with enamel projecting toward the bifurcation.Enamel projection approaching the furcation but not actually making contact with it.Enamel projection extending into the furcation proper.

A myriad of studies continued exploring the prevalence, incidence, and association between CEPs and furcation involvement (Table 5-2).^7,49–55 Variations within these investigations might arise from differences in tooth type, reason for tooth extraction (eg, caries, severe periodontitis, endodontic failure), and patient population. With the exception of Leib et al,⁵⁰ most studies confirmed a positive correlation between CEPs and furcation defects. Notably, Hou and Tsai reported a high prevalence (63.2%) of furcation defects associated with CEPs and intermediate bifurcational ridges (IBRs) affecting primarily mandibular molars.⁵⁵

TABLE 5-2 Prevalence of enamel projections

Authors	Material and methods	Main findings
Masters and Hoskins7	Extracted teethPopulation not specified	Prevalence:– Mandibular molars: 28.6%– Maxillary molars: 17%90% of isolated furcation involvements were associated with CEP
Grewe et al49	Extracted teethPopulation not specified	Prevalence:– Mandibular: 25.2%– Maxillary: 15.8%Frequency (in order):– Mandibular second molars– Maxillary second molars– Mandibular first molars– Mandibular third molars– Maxillary third molars– Maxillary first molars
Leib et al50	Extracted teethPopulation not specified	Prevalence:– Mandibular molars: 25.4%– Maxillary molars: 21.9%Not associated with furcation defects.
Bissada and Abdelmalek51	Egyptian skulls	Incidence:– Overall: 8.6%Frequency (in order):– Mandibular second molars– Maxillary second molars– Mandibular first molars– Mandibular third molars– Maxillary third molars– Maxillary first molars
Tsatsas et al52	Extracted teethPopulation not specified	Prevalence:– Overall: 29.9%
Swan and Hurt53	East Indian skulls	Prevalence:– Overall: 32.6%– Mandibular molars: 33.7%– Maxillary molars: 31.4%Frequency (in order):– Mandibular second molars– Maxillary second molars– Maxillary third molars– Mandibular first molars– Mandibular third molars– Maxillary first molars
Hou and Tsai54	Surgical accessPopulation: Taiwanese	Prevalence:– Overall: 45.2%Frequency (in order):– Mandibular first molars– Maxillary first molars– Mandibular second molars– Maxillary second molars
Hou and Tsai55	Hopeless teeth with Class III FIPopulation: Taiwanese	Prevalence:– FI with CEPs and IBR: 63.2%– FI with CEPs alone: 21.8%– FI with IBR alone: 2.3%

FI, furcation involvement; IBR, intermediate bifurcational ridge.