Although human dental anatomy is taught in university curricula, clinicians often witness restorations that are not proportional to one another. Dental restorations should also be proportional to periodontal supporting tissues as an essential aspect of dental anatomy. Measurements can be performed directly on a patient’s teeth with aesthetic gauges used to confirm the correct position of the supporting osseous topography. This article demonstrates a technique using these gauges to objectively determine the correct position of the underlying hard tissues and render predictable, aesthetic treatment.
Learning Objectives:
This article highlights the use of aesthetic gauges in a clinical crown lengthening procedure. Upon reading this article, the reader should understand:
• The importance of the dentogingival complex in aesthetic dentistry.
• The role of objective measurement tools for guiding crown lengthening procedures
Contemporary periodontal therapy also encompasses aesthetic treatment where needs are frequently asso- ciated with changes in tooth size, shape, proportion, and balance that can negatively affect smile appearance.1 There exists a synergy between periodontics and restora- tive dentistry, where the disciplines are interdependent. In aesthetic dentistry where development of the proper tooth size, form, and color of restorations are critical to clinical success, often the periodontal component is con- siderable and must be addressed for a predictable aes- thetic outcome. The need to establish the correct tooth size and thus individual tooth proportion drives the peri- odontal component of aesthetic restorative dentistry. One specific area of concern is excessively short teeth,2 where the lack of tooth display and excessive gingival display require clinical crown lengthening that can present a clinical dilemma for the aesthetic-oriented periodontist.
There are a myriad of techniques that have evolved over several decades to treat this situation. Techniques that simplify as well as enhance the quality of treatment can provide substantial benefit to both patients and treat- ing practitioners alike. This article describes an innova- tive approach to periodontal aesthetic crown lengthening utilizing measurement gauges specifically designed for a predictable surgical outcome, thus setting a new stan- dard of diagnosis and treatment within the aesthetic zone. Midfacial surgical crown lengthening has tradi- tionally been performed to establish a healthy biologic dimension of the dentogingival complex (DGC) as an adjunct to aesthetic restorative procedures. While con- siderable variation in the magnitude or length of this complex has been reported, the mean sulcus depth was 0.69 mm, epithelial attachment was 0.97 mm, and the connective tissue was 1.07 mm.3 Therefore, the total length of the DGC was 2.73 mm. Based on these dimen- sions, several authors have suggested that 3 mm of supracrestal tooth structure be obtained during surgical crown lengthening.4,5 Other authors have suggested that supracrestal tooth structure ranges from 3.5 mm to 5.25 mm, depending on the placement of the restora- tive margin.6,7 It is important, therefore, to establish a con- sistent measurement representative of the DGC dimension, which is critical for health and restorative success when performing surgical crown lengthening
Herrero et al noted that establishing a constant and desired surpracrestal tooth length is not routinely achieved during surgical crown lengthening.8 Walker and Hansen described the fabrication of a surgical template for aes- thetic restorative crown lengthening.9 This, however, required multiple visits to fabricate such a template prior to surgery. In addition, stability of the template during the surgical procedure was questionable and could lead to inconsistent and unsatisfactory results. Lee described a tooth-formed provisional restoration to be used as a remov- able template for surgical crown lengthening.10 This approach requires multiple presurgical visits to fabricate, presents stabilization concerns at the time of surgery, and increases the cost of treatment. These techniques attempted to standardize the amount of supracrestal length of the DGC to be established, yet they all required addi- tional time and laboratory procedures to accomplish. Traditionally, dental instruments such as periodontal probes have been used as clinical indicators of diseases such as periodontitis, with their numerical values indica- tive of health or stages of disease.11 More recently, instru- mentation (ie, Chu’s Aesthetic Gauges, Hu-Friedy Inc, Chicago, IL) has been created to diagnose and predictably treat aesthetic tooth discrepancies and deformities. Aesthetic and anatomic tooth dimensions can now be eval- uated and treated by quantitative standards. These inno- vative aesthetic gauges have been developed to eliminate the subjective aesthetic outcomes afforded by direct visual assessment of aesthetic tooth proportions
Innovative Instrumentation
Proportion Gauge
The Proportion Gauge (ie, Chu’s Aesthetic Gauges, Hu- Friedy Inc, Chicago, IL) enables an objective mathe- matical appraisal of tooth size ranges in a visual format for the clinician or laboratory technician. Through the use of such instrumentation, the dental professional is able to apply aesthetic values and measurements to a patient chairside (directly) or in the laboratory (indirectly) for projected treatment planning and objective forecast- ing of the intended treatment outcome (Figure 1). The correct incisal edge position must be established before any diagnostic and procedure-based measurement is made. In addition, the correct incisal edge position and tooth size must be determined prior to any irreversible aesthetic periodontal procedure—whether it is clinical root coverage or lengthening.
The Proportion Gauge is designed as a single- handle, double-ended instrument with “T-Bar” and “In-Line” tips screwed into the handle at opposing ends.13 The T-Bar gauge is used to measure a non-crowded anterior dentition and the In-Line for a crowded dentition. The T-Bar tip features an established rest position at the incisal edge position (ie, an incisal stop); when the gauge is seated accordingly, the practitioner can accurately eval- uate its length (vertical arm) and width (horizontal arm) dimensions simultaneously and, therefore, visually assess the correct tooth size and proportion. The width is indi- cated in 0.5-mm increments of color, each with a vertical mark in corresponding color. Thus, a central incisor with a “red” width of 8.5 mm will be in proper proportion if its height is also the “red” height (ie, 11 mm) (Figure 2). The measurements of the Proportion Gauge are based on clinical research of range and mean distribution values of individual tooth size, width,12 and accepted anatomic and clinical proportion ratios.14,15 The majority of patients were found to have a measurement within ±0.5 mm of the mean averages; central incisors (8 mm to 9 mm), lateral incisors (6 mm to 7 mm), and canines (7 mm to 8 mm), being within these ranges in width (Figure 3).
Sounding Gauge
Midfacial clinical crown lengthening involves a multi- faceted decision-making process, with the endpoint being whether hard and soft tissues can be excised and/or should be repositioned.16 The Sounding Gauge (ie, Chu’s Aesthetic Gauges, Hu-Friedy Inc, Chicago, IL) is used in aesthetic periodontal crown-lengthening procedures to determine the level of the bone crest prior to flap reflec- tion. This gauge helps provide quick and simple analy- sis of the osseous crest location midfacially and interdentally.16,17 It has a deliberate curvature of the tip coincident with the curvature of the tooth and root— especially at the cementoenamel junction where it is most prominent. This allows easier negotiation of the osseous crest location, particularly in thin biotype cases where the crest is thin and difficult to detect. The tip of the gauge is also wider than that of a periodontal probe at 1 mm in dimension. This increased dimension allows greater stability and confidence during the sounding process. The Sounding Gauge is fabricated from surgical-grade stainless steel honed to precisely and atraumatically pierce the supracrestal gingival fibers (Figure 4). Laser markings define the average sulcus depth (1 mm) and midfacial DGC (3 mm). In addition, a marking at 5 mm denotes the interdental DGC (5 mm) (Figures 5 through 7)
Crown Lengthening Gauge
The Crown Lengthening Gauge (ie, Chu’s Aesthetic Gauges, Hu-Friedy Inc, Chicago, IL) has a “BLPG Tip” designed to measure the midfacial length of the anticipated restored clinical crown and the length of the biologic crown (ie, bone crest to the incisal edge) simultaneously during surgical crown lengthening (Figure 8). The BLPG tip is designed to replace existing aesthetic crown-lengthening techniques, employing the use of polymer-based surgical guides or templates. The advantages of the Crown Lengthening Gauge over such conventional means are precision during the procedure, where potential movement of the surgical guide is a non-factor, as well as cost efficiency from decreased time and laboratory procedures required for guide/template fabrication. The disposable plastic instrument tip with an incisal rest is color coded with a preset midfacial DGC mea- surement of 3 mm (Figure 9). This is based on the ideal 3-mm DGC or difference recommended between the clinical length and the biologic length of the crown. The color-coded marks on the shorter arm represent the clin- ical crown length, and the corresponding color markings on the longer arm represent the biologic crown length. During the osseous resection procedure, the visualization of both these parameters simultaneously serves the clin- ician to focus on the end goal of treatment since the blue- print for bone removal is clearly delineated (Figures 10 and 11). The short arm of the BLPG tip is of the same length and measurement as the long arm of the T-bar tip of the Proportion Gauge (Figures 3 and 9)
Case Presentation
A 54-year-old female patient presented for an aesthetic restorative consultation during orthodontic treatment. She was undergoing orthodontic treatment to correct a deep overbite relationship as well as correct a midline dis- crepancy. The patient did not like her smile because the preexisting, 20-year-old, full-coverage restorations were wearing and looked artificial. Comprehensive clinical and radiographic examination revealed loss of marginal integrity of the full-coverage restorations with gingival recession exposing the restorative margins. In addition, mild tooth rotations and excess spacing was present fol- lowing orthodontic treatment (Figure 12). The maxillary and mandibular incisors were proclined with inadequate overjet, overbite, and interarch relationships. The patient exhibited a high smile line with asymmetrical free gingival margin architecture.
Objective Analysis of Tooth Proportion
An initial phase of treatment included orthodontic tooth movement to correct arch form, spacing, and overjet/ overbite relationships. The second phase of treatment addressed fabrication of provisional restorations from a diagnostic waxup to reestablish a functional occlusion as well as the correct incisal edge position that harmo- nized with the aesthetic and phonetic needs of the patient (Figure 13). Assessment of attachment levels was per- formed in conjunction with the Proportion Gauge, fol- lowing insertion of the provisional restorations (Figure 14) and Sounding Gauge to accurately identify the gingival sulcus, gingival attachment, and crest of bone, respec- tively (Figure 15).
Tooth size and proportion were found to be undesirable with a width-to-length ratio that was greater then 78% for the maxillary anterior teeth. Inadequate midfacial biologic width was identified on tooth #8(11). Surgical crown lengthening was proposed based on the findings of the gauges (ie, Chu’s Aesthetic Gauges, Hu-Friedy Inc, Chicago, IL). The patient was anesthetized using local anesthe- sia, 4% articaine HCL 1:200,000 epinephrine, bilat- eral buccal infiltrations, and bilateral palatal AMSA injections performed using the STA-System (Milestone Scientific, Livingston, NJ). A papilla preservation incision was performed at the interproximal area to retain the integrity of the papilla tissue. An intrasulcular incision was performed over the direct facial of the anterior teeth to expose the underlying crest and facial alveolar bone. Dissection of a full-thickness flap exposed the underlying osseous topography. Direct clinical assessment utilizing the BLPG tip of the Crown Lengthening Gauge indicated the proper amount of osseous resection to be re-estab- lished (Figure 16). The proper vertical position to estab- lish a biologic width of 3 mm was determined based on idealized tooth proportions, which were first confirmed with the BLPG tip. An apically repositioned flap was secured with periosteal vertical interrupted sutures and 5-0 chromic gut sutures (Figure 17).
The optimum tooth length and free gingival margin location were established prior to and during crown-lengthening surgery using the T-Bar tip (Figure 18), thus ensuring that the final tooth proportion being established post-healing would be congruent with the final aesthetic-restorative outcome. The patient was recalled at four months, where the amount of clinical crown length established could be verified with the Crown Lengthening Gauge or the Proportion Gauge. Final restorations were fabricated in the laboratory and cemented at six months post-surgery (Figures 19 and 20). The integration of tooth proportion and desired measured amount of osseous resection based on tooth dimensions, proportion, and biologic width made these instruments beneficial when utilized in aesthetic crown lengthening surgery (Figure 21).
Conclusion
Human dental anatomy has remained relatively constant for centuries. While human dental anatomy is taught in the dental curriculum, much too often clinicians witness restorations of teeth that are not proportional to one another (Personal communication, J. Greenberg, 2007). These restorations should also have a basic proportional relationship to periodontal supporting tissues as an essen- tial aspect of dental anatomy. This is the first technique that uses optimal tooth pro- portions to determine the correct position of the osseous topography supporting those teeth. Measurements are performed directly on the teeth with disposable and removable aesthetic gauges so that they will not inter- fere with surgical instrumentation. The gauges can be used repeatedly to confirm the amount of midfacial osseous tissue to be removed. Visual precision without guessing or emotional estimation is vital for successful, predictable, cost-efficient treatment
Conclusion
Human dental anatomy has remained relatively constant for centuries. While human dental anatomy is taught in the dental curriculum, much too often clinicians witness restorations of teeth that are not proportional to one another (Personal communication, J. Greenberg, 2007). These restorations should also have a basic proportional relationship to periodontal supporting tissues as an essen- tial aspect of dental anatomy. This is the first technique that uses optimal tooth pro- portions to determine the correct position of the osseous topography supporting those teeth. Measurements are performed directly on the teeth with disposable and removable aesthetic gauges so that they will not inter- fere with surgical instrumentation. The gauges can be used repeatedly to confirm the amount of midfacial osseous tissue to be removed. Visual precision without guessing or emotional estimation is vital for successful, predictable, cost-efficient treatment
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