Clinical and Anatomical Factors Limiting Treatment Outcomes of Gingival Recession: A New Method to Predetermine the Line of Root Coverage
G. Zucchelli, T. Testori, and M. De Sanctis. J Periodontol 2006;77:714-721
The gingival margin is clinically represented by a scalloped line that follows the outline of the cemento-enamel junction (CEJ), 1 to 2 mm coronal to it.Gingival recession is an apical shift of gingival margin with exposure of the root surface to the oral cavity. Gingival recession may involve one or more tooth surfaces. The objective of mucogingival surgery is the treatment of the recession limited to one surface (generally the buccal one) with no associated severe attachment loss at the interproximal surfaces.
In the literature, gingival recessions have been classiﬁed into four classes, according to the prognosis of root coverage. In Class I and II gingival recessions, there is no loss of interproximal periodontal attachment, and bone and complete root coverage can be achieved; in Class III, the loss of interdental periodontal support is mild to moderate, and partial root coverage can be accomplished; in Class IV, the loss of interproximal periodontal attachment is so severe that no root coverage is feasible.
In the recent literature, the root coverage predictability of a mucogingival surgical procedure is measured in terms of the percentage of root coverage (indicating the percentage of the root exposure that is covered with soft tissues after the healing period) and the percentage of complete root surface (showing in which percentage of the treated cases the soft tissue margin has been repositioned at the level of the CEJ). For the correct evaluation of both these parameters, it is necessary to recognize the CEJ, which anatomically separates the crown from the root, on the tooth with the recession defect. Therefore, the clinical healing pattern of only those gingival recessions in which the CEJ is clinically detectable could be evaluated in terms of percentage and/or complete root coverage. When the CEJ is not recognizable, it is no longer possible to measure the depth (and width) of the recession or to assess the efﬁcacy of a surgical technique in terms of root coverage, due to the lack of the referring parameter.
The international literature has thoroughly documented that gingival recession can be successfully treated by several surgical procedures, irrespective of the technique used, provided that the following biologic conditions for accomplishing root coverage are satisﬁed: no loss of interdental soft and hard tissue height.
However, some surgical approaches have been reported to be more predictable compared to others in terms of root coverage: these are the coronally advanced ﬂap (CAF) and the bilaminar techniques.
Even for these procedures, a great variability of clinical outcomes does exist, and data expressed in terms of complete root coverage are always quite far from the desired 100%. It could be argued that some presumed failures (or incomplete successes) in terms of root coverage could be ascribed to mistakes in the selection of the clinical case or of the referring measurement parameters rather than to the inefﬁcacy of the surgical technique.
The aim of the present study was to identify some of the most frequent diagnostic mistakes leading to incomplete root coverage in Miller Class I and II gingival recessions and to suggest a method to predetermine the position of the soft tissue margin after a mucogingival surgical procedure.
Mistakes in Selection of Reference Measurement Parameters
The most frequent mistake in the selection of the reference parameters concerns the localization of the anatomic CEJ on the tooth with the recession defect. In a recent analysis (our unpublished data) on 900 teeth with gingival recession (360 patients), the CEJ was completely detectable in 30% and partially recognizable in 25% of the selected cases. Therefore, there was no sign left of the anatomic CEJ in about half of the examined teeth. In the great majority (>90%) of these teeth, cervical abrasions were associated with the recession of the soft tissue margin. It can be speculated that the etiologic factor, likely traumatic (toothbrushing trauma), may have occurred at the cervical region of the tooth, provoking gingival recession initially and tooth abrasion afterwards. It is highly improbable that the abrasive trauma was limited to the area of the exposed root.
More probably, the abrasive trauma involved the whole cervical area and, thus, both the enamel and the root cementum, causing the disappearance of the anatomic line (CEJ) which separated the crown from the root. In many cases of gingival recessions associated with cervical abrasion, a line separating the enamel from the coronal dentin (exposed due to the abrasion defect) does appear, and this is frequently confused with the anatomic CEJ (Fig. 1A). This error in the localization of the CEJ leads to other measurement mistakes, obviously making the desired root coverage unobtainable. In fact, the patient hopes for a complete coverage of the exposed dentin, but this result is not achievable because the most coronal portion of the exposed dentin belongs to the anatomic tooth crown, and thus it is notcoverable with the soft tissues. Post-surgical dentin exposure may be erroneously considered a failure (or incomplete success) of the root coverage surgical technique (Fig. 1B).
To avoid this mistake, the clinician must carefully observe the outline of the line he/she considers to be the anatomic CEJ. In fact, this line has a curved, convex outline, more or less scalloped, according to the patient’s biotype. On the contrary, in the great majority of cases, the abrasion lines are ﬂat.
The differential diagnosis between abrasion line and anatomic CEJ is often more difﬁcult in posterior teeth (premolar and molar), which are characterized by a ﬂatter outline of the CEJ even in a thin and scalloped patient’s biotype. Nevertheless, a careful observation (better with magniﬁcation lenses) Will allow the clinician to distinguish the straight (sometimes concave) outline of the abrasion line from the more scalloped and convex outline of the anatomic CEJ.
Mistakes in the Selection of the Clinical Case
The following local conditions at the tooth with the recession defect may limit root coverage even in the absence of interdental attachment and bone loss: 1) loss of the interdental papilla(e) height; 2) tooth rotation; 3) tooth extrusion; and 4) occlusal abrasion. If the clinician does not recognize these situations as factors impairing complete root coverage, the persistence of root exposure after surgery could be erroneously considered a failure of the root coverage surgical procedure.
Loss of interdental papilla(e) height (Figs. 2 and 3). In subjects with thin and highly scalloped biotype, the interdental papillae are long, thin, and triangular-shaped with sharp tips. In a healthy periodontium of non-molar teeth, the papillae ﬁll the interdental space up to the contact point between adjacent teeth.
This long papilla, and particularly the tip of it, is very delicate because it is histologically characterized by a keratinized epithelium supported by a thin and thus poorly vascularized connective tissue. Improper use (by the patient or by the dental hygienist) of hygienic interdental tools may traumatize the tip of this papilla, thereby causing recession. Loss of the papilla height can also be caused by inﬂammatory periodontal disease due to bacterial plaque (gingivitis). In cases of trauma and gingivitis, there is no loss of interdental periodontal attachment and bone.
During mucogingival surgery, the interdental papillae (once disepithelized) act as the most coronal vascular beds to which the soft tissues covering the root exposure are anchored (sutured). A loss of papilla height will decrease the potential advancement of the coronal ﬂap and reduce the vascular exchanges between the root covering soft tissues and the interdental connective tissue.
Extrapolating from the Miller classiﬁcation, a tooth with gingival recession and with no loss of interdental attachment and bone requires a deﬁnite papilla height so that complete root coverage can be accomplished; if some papilla(e) is lost, coverage up to the CEJ cannot be achieved.
Tooth rotation (Fig. 4). In a rotated tooth, the topographic relationship between the CEJ and the interdental papillae, mesial and distal to the tooth with recession, changes: at one tooth side (mesial or distal according to the sense of rotation), the CEJ gets closer to the tip of the papilla, whereas at the other side, it gets farther. The situation in which the CEJ gets closer to the tip of anatomic papilla conﬁgures a condition of a loss of papilla height clinically similar to that caused by trauma. The only difference between these situations is that one or both of the interdental papillae can be involved in the case of traumatic loss, whereas in the case of tooth rotation, the height of only one papilla is reduced. Root coverage surgical techniques will leave a portion of root surface uncovered at the tooth side where there is reduction of papilla height; this is often erroneously considered a failure of the root coverage procedure.
Tooth extrusion (Fig. 5). Loss of an antagonist tooth or more complex occlusal disorders may induce extrusion of a single tooth with no associated extrusion of supporting interdental periodontal tissues. In an extruded tooth, the CEJ gets closer to the tip of both interdental papillae, and thus a condition of bilateral reduction of interdental papillae height is created. In this case, too, it is not possible to cover gingival recession up to the anatomic CEJ, and the persistence of a root exposure (the depth of which should correspond to the amount of tooth extrusion) must not be considered a failure of the root coverage surgical procedure.
Occlusal abrasion (Fig. 6). The speciﬁc type of occlusion/malocclusion or more complex parafunctions may induce occlusal abrasion phenomena. Occlusal abrasion is frequently associated with progressive tooth extrusion (tooth eruption continues until reaching the antagonist tooth), which, by itself, conﬁgures a condition of bilateral loss of interdental papillae. A tooth with occlusal abrasion is frequently extruded, and thus, in the presence of gingival recession, it cannot be completely covered with the soft tissue up to the level of the anatomic CEJ.