Biologic width - Importance in Periodontal and Restorative Dentistry

Biologic width plays a vital role for preservation of the periodontal health. This concept involves the dimensions of the epithelial and connective tissue attachment between the base of the sulcus and the alveolar crest which if involved can lead to gingival inflammation and gingival recession.

1. BIOLOGIC WIDTH - ROLE IN PERIODONTAL AND RESTORATIVE DENTISTRY Presented by – Dr. Shraddha Kode

2. INTRODUCTION For fractured (traumatized), severely decayed, partially erupted, worn or poorly restored teeth – Surgical or orthodontic intervention is required It is essential to adhere to the basic biologic principles to prevent impingement on the periodontal attachment apparatus or BIOLOGIC WIDTH

3. First described by Sicher in 1959. Terminology described in 1977 by Ingber etal Dr. Walter Cohen coined the term in 1962 Biologic width is the term applied to the dimensional width of the dentogingival junction(epithelial attachment and underlying connective tissue).

4. Biologic width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of alveolar bone. Nevins and Skurow (1984) defined biologic width as the sum of the combined supracrestal fibers, the junctional epithelium, and the sulcus. This was over 3 mm when measured from the crest of bone.

5. Also called ‘PERIODONTAL ATTACHMENT LAMINA’ Term satisfies not only the EXCLUSIVITY of the tissue to the periodontium , but also gives a sense of its FUNCTIONAL IMPORTANCE in dealing with interdisciplinary treatment approaches, where NO VIOLATION IS APPRECIATED .

6. Gargiulo et al reported in 1961 a uniformity of the dimension of components of biological width: —mean depth of the histologic sulcus is 0.69 mm, —mean junctional epithelium measures 0.97 mm (0.71 to 1.35 mm), —mean supraalveolar connective tissue attachment is 1.07mm (1.06 to 1.08 mm). Total attachment therefore is 2.04 millimetres (1.77 to 2.43mm)

7. The actual biologic width (dentogingival junction) in adults is 1.80 mm and 1.77 mm which is less than the universally accepted 2.04 mm. SIGNIFICANCE

8. Vacek and colleagues (1994) – BW increased anteroposteriorly (1.75 to 2.08 mm) and that 15% of the restorations that impinged in the biologic width had a biologic width of less than 2.04 mm. Because of the anteroposterior increase in BW, the clinician may want to increase the amount of tooth structure exposed when performing crown-lengthening procedures.

9. Kois (1994) and Spear (1999) –Dentogingival complex is 3.0 mm facially and 4.5 to 5.5 mm interproximally. Height of the interdental papilla can only be explained partially by the increased scalloping of the bone.

10. Becker and colleagues (1997) – Variations of gingival scallop by the distance in gingival tissue height between the facial and interproximal areas: FLAT – 2.1mm SCALLOPED – 2.8mm PRONOUNCED SCALLOPED – 4.1mm The average height difference is 3.0 to 3.5 mm (Wheeler, 1961).

11. Subject that belongs to the “pronounced scalloped” gingival biotype. The crowns of the teeth are comparatively long and slender . The papillae are comparatively long, the gingival margin is thin and the zone of attached gingiva is short . Subject that belongs to the “ flat ” gingival biotype. The crowns of the teeth are comparatively short but wide . The papillae are comparatively short but voluminous and the zone of attached gingiva is wide.

12. Olsson & Lindhe (1991) - Subjects with pronounced scalloped gingiva often exhibited more advanced soft tissue recession than subjects with a flat gingiva

13. Tarnow and colleagues (1992) - For the gingival tissue to assume complete filling of the interdental space, the distance from the contact point to the osseous crest should not exceed 5 to 5.5 mm. Greater distances result in significant loss of gingival height

14. Some bone resorption takes place during healing and that the biologic width of the new connective tissue attachment re-establishes coronal to the level of the resected osseous crest.

15. MARGIN PLACEMENT AND BIOLOGIC WIDTH Three options for margin placement: SUPRAGINGIVAL – Least impact on periodontium Preparation, duplication, finishing of margins easier Facilitates plaque control But un- esthetic EQUIGINGIVAL – Aesthetically blends with the tooth and finished easily

16. From a periodontal viewpoint, both supragingival and equigingival margins are well tolerated SUBGINGIVAL – Greatest biologic risk When the restoration margin is placed too far below the gingival tissue crest; it impinges on the gingival attachment apparatus and creates a violation of biologic width

17. 2 responses from gingival tissues: BONE RESORPTION that recreates space for BW to attach normally GINGIVAL RECESSION as the body attempts to recreate room between alveolar bone and margin to allow space for tissue reattachment GINGIVAL HYPERPLASIA seen with minimal or no bone loss (thick gingival biotype)

18. The first step in using sulcus depth as a guide in margin placement is to manage gingival health. Once the tissue is healthy, the following three rules can be used to place intracrevicular margins. RULE 1 - If the sulcus probes 1.5mm or less, place the restoration margin 0.5mm below the gingival tissue crest.

19. RULE 2 - If the sulcus probes more than 1.5mm,place the margin one half the depth of the sulcus below the tissue crest. RULE 3 - If a sulcus greater than 2mm is found, especially on the facial aspect of the tooth then evaluate to see whether a gingivectomy could be performed to lengthen the teeth and create a 1.5mm sulcus. Then the patient can be treated using Rule 1

20. STUDIES Orkin et al (1987) Subgingival restorations had a greater chance of bleeding and exhibiting gingival recession than supragingival restorations. Waerhaug (1978) Subgingival restorations accumulate plaque even in the presence of adequate supragingival plaque control Stetler & Bissada (1987) Clinicians should consider gingival augmentation for teeth with minimal keratinized gingiva before placing subgingival restorations. Dragoo & Williams (1981) Compromised healing associated with gingival bevel crown margins compared to shoulder preparations Flores-de-je- Coby etal (1989) Subgingival margins demonstrated increased plaque, gingival index scores, and probing depths. More spirochetes, fusiforms, rods, and filamentous bacteria were found to be associated with subgingival margins Valderhaug & Birkeland (1986) Greater mean attachment loss was associated with subgingival restorations compared to supragingival margins (1.2 versus 0.6mm).

21. Kois described three categories of biologic width as Normal Crest – 85% Mid facial measurement = 3mm, Proximal = 3 to 4.5mm Gingiva stable for a long time High Crest – 2%, unusual finding in nature Mid facial measurement is less than 3mm Proximal surface adjacent to edentulous site Low Crest – 13% Mid facial measurement > 3mm, Proximal measurement > 4.5mm Susceptible to recession after placement of intracrevicular margins

22. EVALUATION OF BIOLOGIC WIDTH VIOLATION CLINICAL METHOD If a patient is having discomfort when restorative margin levels are assessed with a probe , it is a good indication for biologic width violation. BONE SOUNDING The biologic width can be identified for each individual patient by probing under anaesthesia to the bone level and subtracting the sulcus depth from the resulting measurement.

23. If this distance is less than 2mm at one or more locations, then a violation of biologic width can be diagnosed.

24. RADIOGRAPHIC EVALUATION Radiographic evaluation can assess interproximal violation of biologic width. But it is not diagnostic because of tooth superimposition So, PARALLEL PROFILE RADIOGRAPH TECHNIQUE was introduced to measure dimensions of dentogingival unit

25. METHODS TO CORRECT BIOLOGIC WIDTH VIOLATION SURGICAL CORRECTION - Removing the bone away from the restorative margin Done by gingivectomy, apically repositioned flap with or without ostectomy. ORTHODONTIC CORRECTION - Tooth is moved coronally away from the bone Done either by slow eruption or forced eruption with supracrestal fiberotomy.

26. SURGICAL CROWN LENGTHENING INDICATIONS CONTRAINDICATIONS Inadequate clinical crown for retention due to extensive caries, subgingival caries or tooth fracture, root perforation, or root resorption within the cervical1/3rd of the root in teeth with adequate periodontal attachment. Short clinical crowns & Placement of sub gingival restorative margins Unequal, excessive or unaesthetic gingival levels Planning veneers or crowns on teeth with the gingival margin coronal to the cemento-enamel junction Teeth with excessive occlusal wear or incisal wear or inadequate interocclusal space Restorations which violate the biologic width In conjunction with tooth requiring hemisection or root resection Deep caries or fracture requiring excessive bone removal Post surgery creating unaesthetic outcomes Tooth with inadequate crown root ratio (ideally 2:1 ratio is preferred) Non restorable teeth Tooth with increased risk of furcation involvement Unreasonable compromise of esthetics Unreasonable compromise on adjacent alveolar bone support

27. EXTERNAL BEVEL GINGIVECTOMY Done in cases of hyperplasia or pseudo pocketing (> 3 mm of biologic width) and presence of adequate amount of keratinized tissue. INTERNAL BEVEL GINGIVECTOMY Done in cases of absence of a sufficient zone of attached gingiva with or without the need for correction of osseous abnormalities

28. APICAL REPOSITIONED FLAP WITH OSSEOUS REDUCTION Done in cases of no adequate zone of attached gingiva and the biologic width is less than 3 mm The alveolar bone is reduced by ostectomy and osteoplasty to follow the desired contour of the overlying gingiva.

29. As a general rule, at least 4 mm of sound tooth structure must be exposed, so that the soft tissue will proliferate coronally to cover 2-3 mm of the root, thereby leaving only 1-2 mm of supragingivally located sound tooth structure (Pontoriero R etal 2001, Elavarasu S 2010)

30. FORCED ERUPTION Cases where traditional crown lengthening via ostectomy cannot be accomplished, like in the anterior area, as ostectomy would lead to a negative architecture Contraindications include inadequate crown-to-root ratio, lack of occlusal clearance for the required amount of eruption and any possible periodontal complications Two concepts of forced eruption: Forced eruption with minimal osseous resection, and forced eruption combined with fiberotomy.

31. BIOLOGIC WIDTH AROUND IMPLANTS Junctional epithelium facing the implant or abutment surfaces is thin in its apical portion (40μm mean width) The structure of the peri -implant junctional epithelium is similar to that of natural dentition, with the exception that it is shorter and thinner

32. The differences between peri-implant tissues and periodontal attachment apparatus include lack of a periodontal ligament around implants, different orientation of connective tissue fibers and vascular distribution

33. FACTORS INFLUENCING PERI-IMPLANT BIOLOGIC WIDTH SURFACE TOPOGRAPHY IMPLANT AND ABUTMENT MATERIALS SURGICAL PROTOCOL LOADING TIME IMPLANT MACRO-DESIGN AND MICRO-GAP POSITION

34. IMMEDIATE IMPLANT PLACEMENT FOLLOWING TOOTH EXTRACTION MUCOSAL THICKNESS MAXILLA VS MANDIBLE FLAP VS FLAPLESS TECHNIQUE

35. CONCLUSION There is general agreement that a minimum of 3 mm should exist from the restorative margin to the alveolar bone, allowing for 2 mm of biologic width space and 1mm for sulcus depth. Periodontal health depends on appropriately designed restorations with correctly placed margins without violating the biologic width. Evidence suggests that even minimal encroachment on sub-gingival tissues leads to deleterious effects on the periodontium

36. If dimensions are found to be insufficient, the most appropriate corrective procedure - surgical or orthodontic can be undertaken for establishment of sufficient width. The factors to be considered while placing sub-gingival margins are proper contour , correct polishing and rounding of gingival margins, adequate attached gingiva, careful removal of excess cement, and finally no biologic width encroachment by the restorative margin. Periodic maintenance visits with proper home care are essential for a healthy and functional periodontium around the restored tooth.

37. REFERENCES Babitha Etal; Biologic Width And Its Importance In Periodontal And Restorative Dentistry; Journal Of Conservative Dentistry | Jan-mar 2012 | Vol 15 | Issue 1 Maheaswari Etal; Biologic Width - Critical Zone For A Healthy Restoration ; (IOSR-JDMS); Volume 13, Issue 2 Ver. Iv. (Feb. 2014), Pp 93-98 Atlas Of Cosmetic And Reconstructive Periodontal Surgery; Edward S. Cohen Lindhe 5 th Edition Preetha Etal; Biologic Width And Its Importance In Dentistry; JMSCR Volume||2||issue||5||page 1242-1248||may 2014 Ashu Etal; Biological Width: No Violation Zone; | European Journal Of General Dentistry | Vol 1 | Issue 3 | September- december 2012 | Chatterjee Souvik Etal; REVIEW ARTICLE BIOLOGICAL WIDTH OR PERIODONTAL ATTACHMENT LAMINA (PAL); Journal Of Advance Researches In Biological Sciences, 2014, Vol. 6 (3&4) 297-302 Zeinab Rezaei Esfahrood Etal; Biologic Width Around Dental Implants: An Updated Review; JDMT, Volume 5, Number 2, June 2016