Biological Width

A very important trend in dentistry nowadays is represented by the increased attention paid to the connection between periodontal and prosthetic treatments. This connection is the weak point (“Achilles’ heel”) and the place where patients most often notice that “ the tooth is a fake ”. 

Any successful esthetician should ideally have a skilled periodontist as a very good friend or he/she should learn such skills. More and more emphasis is being placed on pink esthetics and the junction between the tooth and the gum. The aspects in which periodontics for esthetic purposes can be of great assistance are : 
  • Making correct gingival outlines with the symmetry of the central incisors and the gingival level of the lateral incisors below the tangent between the canines and the centrals.
  • Making the correct gingival zeniths. 
  • Obtaining correct dental proportions. 
  • Obtaining more thickness in the fixed gingiva in order to mask the dark color of the dental root through a thin periodontium.
  • Remaking the outline of the vestibular cortical bone, both for implants and for the edentulous ridge in the anterior area. 
  • Covering the gingival retractions.
  • Reconstructing the papillae.
  • Treating gingival excess.
  • Preparing the site for the ovate pontic in the edentulous ridge.
All these surgical periodontal techniques have the role of improving the pink esthetic score, which will ensure a special final aspect and will maintain the health of the periodontal complex. Some clinical cases will be presented in the next post, which exemplify the idea of interdisciplinarity in esthetic treatments. 

It is essential to present the fundamentals that rule the interactions between Periodontics and Restorative Dentistry. Periodontics, a comprehensive field, should not be linked solely to the presence of bleeding, inflammation, calculli or pockets. It’s scope is broader than the simple execution of scaling and other surgical procedures. Actually, performing most restorative procedures requires a certain knowledge of periodontics since the presence of periodontal health is essential for the maintenance or recovery of esthetics, biology and the masticatory function of the patient. Thus it can be said that acting with periodontal awareness - even when the procedures are strictly restorative - is essential for the success of any treatment. Thus it is mandatory to know the major periodontal structures for practicing restorative dentistry as well as the spatial relationships between them.

With regard to the interaction of restorations to the periodontium, the most important region is that portion between the tooth, the crestal bone and the cervical margin of the restoration. In this region, the biological components responsible for the maintenance of periodontal homeostasis are inserted. The connective insertion and the junctional epithelium together compose the biological width, defined as the height of the gingival tissue to the tooth inserted coronally to the bone crest. The dimensions of each of the components of the biological width were determined from findings of histological studies, with the following average values: junctional epithelium (0.97 mm) and connective insertion (1.07 mm) with the sum of 2.04 mm . The gingival sulcus is 0.69 mm by the way. These values are determined biologically, ranging between individuals, between teeth and between different surfaces of the same tooth.

The adherence of these structures to the dental tissue - through dentogingival fibers to the connective tissue attachment and through hemidesmosomes to the junctional epithelium - results in an organic sealing around the tooth neck. This allows for the host to maintain periodontal health against continuous bacterial invasion. The gingival sulcus, on the other hand, does not present any adherence to the tooth surface and therefore may be broken during restorative procedures, without prejudice to the periodontal homeostasis. Since its average length is only 0.69 mm, it has been suggested that - if necessary - the preparations may be extended up to 0.5 mm within the sulcus. Therefore the margin is restricted to the intrasulcular area without compromising its biological seal. However, when the biological width is invaded and consequently the dentogingival attachment is compromised whether by pathological (e.g. carious lesion), traumatic (e.g. fractures) or iatrogenic processes (e.g. inappropriate placement of the preparation margins), there is a disruption of the organic seal allowing bacteria and their byproducts to reach the underlying connective tissue which can result in inflammation.

Since the biological width is violated, the body itself - as a general rule - is responsible for promoting resorption of the bone crest to allow apical migration of its components. Of course the tissues's response to aggression is different for each individual, but usually it is expressed via gingival recession or periodontal pocket formation. Recession is more common in regions where the alveolar bone plate is thin and sharp, while pockets are usually formed in regions of dense bone and thick gingiva. It should be emphasized that the early diagnosis of the invasion of the biological width is critical - small localized changes can indicate early and easily manageable problems. There is a great body of evidence that the destruction of the periodontal attachment device is preceded by inflammatory changes in the region of the margin. Regarding the appearance of the gingival tissue , one should observe not only its shade - this varies greatly between individuals - but the chromatic pattern in an attempt to detect localized changes.

The correction of the biological distances whether by a surgical or a non-surgical approach and the elimination of the inflammation are essential conditions for the implementation of a restorative treatment that will not interfere with the local homeostasis of the periodontium.

Stay tuned for the upcoming post ,, Esthetic Crown Lengthening

regards ..