Periodontics. Fernando Suarez

      The interdental gingiva or papilla refers to the soft tissue that occupies the space between the teeth and consists of an epithelium with a subjacent dense connective tissue. The shape of this interdental gingiva is determined by the morphology of the teeth and the CEJ. In anterior sites, it presents with a pyramidal shape, whereas in posterior sites, it presents with a concave shape. The epithelium that covers this concave portion is known as the col epithelium.^28,30

      SUPRACRESTAL TISSUE ATTACHMENT

      The junctional epithelium and connective tissue attachment together are known as the supracrestal attached tissues (formerly referred to as biologic width).^2,31 The dimensions of these structures were investigated by Gargiulo et al³² and Vacek et al³³ in human cadavers reporting an average distance of 2.04 mm and 1.91 mm, respectively (Table 1-5).

TABLE 1-5 Classic studies on the dimensions of supracrestal tissue attachment and sulcus

	Sulcular epithelium (mm)	Junctional epithelium (mm)	Connective tissue (mm)
Gargiulo et al32	0.69	0.97	1.07
Vacek et al33	1.34	1.14	0.77

      A meta-analysis by Schmidt et al³⁴ in 2013 concluded that the biologic width ranges from 2.15 mm to 2.30 mm, with posterior teeth having longer junctional epithelium and the dimension of connective tissue attachment being larger in buccal and lingual surfaces compared with interproximal sites.³⁴

      Peri-Implant Attachment Apparatus

      The replacement and restoration of the missing dentition by means of dental implants has become a routine procedure in daily practice. As such, a plethora of systems with different macro- and microstructures are available on the market. However, independently of the design, the proper functioning of dental implants is primarily based on the process of osseointegration. This phenomenon is defined as the direct contact between the surface of a loaded implant and vital bone.

      Considerable differences exist between the structures giving support to dental implants and natural dentition, the most important being the lack of PDL for osseointegrated implants. However, at the most coronal portion, some similarities can be found. Similar to the supracrestal attached tissues in the natural dentition, implants also present in their most coronal portion with a sulcus epithelium, junctional epithelium, and connective tissue.³⁵ In 1991 in an animal model, Berglundh et al³⁵ described the differences in the arrangement of collagenous fibers in the connective tissue between teeth and implants. Essentially, while the collagenous fibers run perpendicular to the axis of the tooth, they run parallel to the surface of an implant. The composition of the connective tissue also seems to differ between implants and teeth. As such, more collagen and fewer cells have been found around dental implants in comparison with teeth.³⁵ Moon et al³⁶ also described that although generally a reduced number of cells have been found in the periimplant tissue, a cell-rich zone is present in the connective tissue adjacent to the implant-abutment surface with high concentration of fibroblasts.

      The absence of PDL space around dental implants also determines the lack of vascularization from this structure. Consequently, the blood vessels that irrigate the periimplant mucosa are terminal branches from the periosteum. On the other hand, both natural dentition and dental implants present with a vascular plexus adjacent to the junctional epithelium.³⁷

      References

      1. American Academy of Periodontology. Glossary of Periodontal Terms. American Academy of Periodontology, 2001.

      2. Jepsen S, Caton JG, Albandar JM, et al. Periodontal manifestations of systemic diseases and developmental and acquired conditions: Consensus report of workgroup 3 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. J Periodontol 2018;89(suppl 1):S237–S248.

      3. Nanci A, Bosshardt DD. Structure of periodontal tissues in health and disease. Periodontol 2000 2006;40:11–28.

      4. Sicher H. The principal fibers of the periodontal membrane. Bur 1954;55:2–6.

      5. Schroeder HE. Handbook of Microscopic Anatomy. Vol 5: The Periodontium. Berlin: Springer-Verlag, 1986.

      6. Cho MI, Garant PR. Development and general structure of the periodontium. Periodontol 2000 2000;24:9–27.

      7. Goseki T, Shimizu N, Iwasawa T, Takiguchi H, Abiko Y. Effects of in vitro cellular aging on alkaline phosphatase, cathepsin activities and collagen secretion of human periodontal ligament derived cells. Mech Ageing Dev 1996;91:171–183.

      8. Narayanan AS, Page RC. Connective tissues of the periodontium: A summary of current work. Coll Relat Res 1983;3:33–64.

      9. Bartold PM. Connective tissues of the periodontium. Research and clinical implications. Aust Dent J 1991;36:255–268.

      10. Schroeder HE, Scherle WF. Cemento-enamel junction: Revisited. J Periodontal Res 1988;23:53–59.

      11. Neuvald L, Consolaro A. Cementoenamel junction: Microscopic analysis and external cervical resorption. J Endod 2000;26:503–508.

      12. Bosshardt DD, Selvig KA. Dental cementum: The dynamic tissue covering of the root. Periodontol 2000 1997;13:41–75.

      13. Foster BL, Popowics TE, Fong HK, Somerman MJ. Advances in defining regulators of cementum development and periodontal regeneration. Curr Top Devl Biol 2007;78:47–126.

      14. Presland RB, Dale BA. Epithelial structural proteins of the skin and oral cavity: Function in health and disease. Crit Rev Oral Biol Med 2000;11:383–408.

      15. Ainamo J, Löe H. Anatomical characteristics of gingiva. A clinical and microscopic study of the free and attached gingiva. J Periodontol 1966;37:5–13.

      16. Shirmohammadi A, Faramarzie M, Lafzi A. A clinical evaluation of anatomic features of gingiva in dental students in Tabriz, Iran. J Dent Res Dent Clin Dent Prospects 2008;2:90–94.

      17. Orban B. Clinical and histologic study of the surface characteristics of the gingiva. Oral Surg Oral Med Oral Pathol 1948;1:827–841.

      18. Kyllar M, Witter K, Tichy F. Gingival stippling in dogs: Clinical and structural characteristics. Res Vet Sci 2010;88:195–202.

      19. Ainamo A. Influence of age on the location of the maxillary mucogingival junction. J Periodontol Res 1978;13:189–193.

      20. Ainamo A. Optimal reference line for determination of the location of the maxillary mucogingival junction in the orthopantomogram. Proc Finn Dent Soc 1977;73:70–75.

      21. Bowers GM. A study of the width of the attached gingiva. J Periodontol 1963;34:201–209.

      22. Voigt JP, Goran ML, Flesher RM. The width of lingual mandibular attached gingiva. J Periodontol 1978;49:77–80.

      23. Hormia M, Owaribe K, Virtanen I. The dento-epithelial junction: Cell adhesion by type I hemidesmosomes in the absence of a true basal lamina. J Periodontol 2001;72:788–797.

      24. Bartold PM, Walsh LJ, Narayanan AS. Molecular and cell biology of the gingiva. Periodontol 2000 2000;24:28–55.

      25. Shimono M, Sugira K, Yamamura T. Intercellular junctions of normal human gingival epithelium. A study using freeze-fracture. Bull Tokyo Dent Coll 1981;22:223–236.

      26. Lang NP, Lindhe J. Clinical Periodontology and Implant Dentistry, ed 6. Ames, IA: Wiley Blackwell, 2015.

      27. Kobayashi K, Rose GG, Mahan CJ. Ultrastructure of the dento-epithelial junction. J Periodontal Res 1976;11:313–330.

      28. Schroeder HE, Listgarten MA. The gingival tissues: The architecture