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200501PPAD_Chu.qxd 1/13/05 7:04 PM Page A C O N T I N U I N G E D U C A T I O N X X RESTORATIVE SPACE MANAGEMENT: TREATMENT PLANNING AND CLINICAL CONSIDERATIONS FOR INSUFFICIENT SPACE KIM Jason Kim, CDT, MDT* • Stephen Chu, DMD, MSD, CDT, MDT† • Galip Gürel, DDS‡ • George Cisneros, DMDII JANUARY/FEBRUARY 17 1 In attempting to provide a restorative solution for cases that have been compromised by spatial considerations, clinicians have traditionally opted for an orthodontic approach that did not provide optimal aesthetics due to changes in tooth morphology, specifically tooth size and shape as a result of dental deterioration. With the advent of contemporary aesthetic materials and preparation techniques, clinicians and technicians are now empowered to deliver a penultimate result with minimal compromise to the surrounding dentition. This article presents the clinical and laboratory considerations that must be addressed when providing a prosthetic restoration for crowded teeth. Learning Objectives: This article discusses an option outside of orthodontics in the restoration of cases that are compromised by spatial considerations. Upon reading this article, the reader should: • Be able to address the clinical factors needed with spatially compromised cases. • Understand laboratory considerations in the restoration of such cases. Key Words: orthodontic, aesthetic, space, tooth proportion * Master dental technician, Jason J. Kim Dental Laboratories/International Oral Design, New York, NY. † Clinical Associate Professor and Director, Advanced and International Programs in Aesthetic Dentistry, Department of Implant Dentistry, New York University College of Dentistry, New York, NY; private practice, New York, NY. ‡ Private practice, Istanbul, Turkey. II Professor and Chairperson, Department of Orthodontics, New York University College of Dentistry, New York, NY. Stephen J. Chu, DMD, MSD, CDT, MDT, 205 East 64th Street, Ste. 502, New York, NY 10021 Tel: 212-980-9310 • Fax: 212-980-9647 • E-mail: [email protected] Pract Proced Aesthet Dent 2005;17(1):A-X A 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page B Practical Procedures & AESTHETIC DENTISTRY O rthodontic therapy represents an excellent, predictable means of achieving tooth movement to address aes- thetic and functional concerns. Most patients can benefit functionally and aesthetically from orthodontic therapy. This is particularly true in patients who present with a crowded smile (dentition), commonly marked by overlapping and misaligned teeth. The benefits of orthodontic therapy from a periodontal, restorative, and cosmetic point of view are well-documented.1 Periodontal defects can be reduced, and restoratively compromised teeth can be salvaged through orthodontic forced eruption.2 This technique is used to correct cosmetic midfacial soft tissue discrepancies in Figure 2. Appearance of the mandibular arch prior to preparation. Note the misaligned teeth. the gingival architecture.3 It enhances aesthetics by reestablishing proper tooth proportions and altering the location of the midfacial and interproximal gingival tissues, often called the interdental papilla. Innovative materials (eg, temperature-sensitive/ activated archwires, ceramic brackets), combined with new techniques in contemporary orthodontic therapy, have led to the development of aesthetic and efficient treatment devices as well as streamlined treatment times. These developments have given rise to a greater level of acceptance of orthodontics in the adult patient population. Even with these advances in treatment, some patients may refuse orthodontic therapy due to occupational limitations of time and appearance during treatment. The development and introduction of removable, acrylic-based Figure 3. On the preoperative stone model, red lines indicate the ideal arch restored position, and blue lines indicate required reduction. orthodontic aligners has increased patient acceptance, particularly those resistant to fixed appliances. Although treatment with aligning appliances has many benefits, there are limitations as well. In addition, some questions have been raised with respect to stability of treatment outcomes, specifically, long-term retention of rotational corrections present in the crowded dentition postoperatively.4 The potential for orthodontic relapse has inspired the use of tooth preparation and restorative dentistry to recreate tooth dimensions and proportions commensurate with postorthodontic results from both an aesthetic and functional clinical Figure 1. Preoperative appearance of the patient who presented for treatment of severe overcrowding. B Vol. 17, No. 1 outcome, thereby eliminating the potential for relapse and the need for forced orthodontic tooth movement.5 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page C Kim dentist performs reconstructive dentistry by tooth restoration. The quantity of tooth structure removed must be defined and limitations established to avoid subsequent problems associated with overly aggressive removal of uncompromised tooth structure. Biologic and Structural Parameters The parameters for RSM are defined by the dimensions and structures of the teeth and surrounding periodontium within the dental arches. There are limits to the degree of tooth structure that can be removed before pulFigure 4. Mesiodistal overlaps (marked with blue) will require reduction necessary to allow subsequent expansion of the arch form. pal and periodontal violation result. Since the pulpal chamber size decreases with age, this parameter is influenced by the individual characteristics of each case and the age of the patient. Excessive tooth removal to accomplish the goals of therapy may require mutilation of the remaining tooth structure, thus compromising the biologic and structural outcomes from three essential aspects: endodontic instability regarding questionable pulpal health and long-term prognosis of root canal treatment; structural instability of the remaining tooth structure to support the restoration and/or occlusal scheme; and periodontal instability caused by resultant changes in restorative tooth morphology (eg, unfavorable proximal contours that could impede proper oral hygiene and Figure 5. Approximately 2 mm of buccolingual overlap was evident and a mesiodistal overlap of less than 1 mm was also observed. encourage food impaction and plaque retention). One must consider the aforementioned guarded consequences Restorative Space Management (RSM) is defined as therapy that uses tooth preparation techniques and designs to accomplish the goals of orthodontic therapy. It requires selective and strategic removal of tooth structure and the addition of cosmetic restorative materials (eg, direct/indirect restorations). Unlike traditional orthodontic therapy, the benefits of RSM include correction of tooth shapes and dimensions that improve tooth proportions, as well as color correction, concomitantly. The goals of therapy for the orthodontist and restorative dentist are similar; how they achieve the results is the only difference. The orthodontist achieves his or her Figure 6. The necessary buccal and lingual parameters were modified to facilitate development of an ideal arch form. goals through tooth movement, while the restorative PPAD C 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page D Practical Procedures & AESTHETIC DENTISTRY Figure 7. A mock-up was created to visualize the anticipated postoperative tooth form. Figure 8. Incisal index of the mock-up. Pencil lines indicate proper spatial relationship and width of teeth at the incisal aspect. afforded by such therapy without regard for the aesthetic Space is frequently gained by preparing the pos- and functional effects. In addition, negative gingival and terior teeth in ways that require removal from the mesial interdental papilla architecture cannot be remediated aspect and addition to the distal aspect. Moderate through RSM treatment. crowding can often be successfully treated using this technique. An average of 1 mm to 1.5 mm of total reduc- Treatment Planning tion per tooth can be comfortably obtained due to the Tooth crowding can pose an intellectual and techni- interproximal contours of teeth and the anatomy of avail- cal challenge, since both mesiodistal and buccolin- able enamel.8 When multiplied by the number of teeth gual discrepancies must be addressed. Resultant involved, the result should give adequate space to realign periodontal instability can be more of a contraindi- the crowded dentition. cation in these cases. The objectives of RSM therapy Buccolingual changes in tooth position can be asso- in a case with insufficient space are to restore proper ciated with discrepancies in gingival architecture (eg, tooth proportions and establish a stable physiologic midfacial tissue height, papilla height, papilla shape) occlusion. Ward identified the “recurring esthetic that require adjunctive periodontal therapy or orthodon- dental” or RED proportion, which is the width-to-length tic correction. Mild-to-moderate discrepancies, such as proportion of the maxillary teeth that falls between Class I and Class II case types, are easily and predictably 75% and 80%.6 Invariably, this requires the creation treated by RSM. Severe case types, such as Class IV, of space to straighten the anterior dentition. The could require tooth mutilation as well as significant peri- resultant “Tooth Proportion” formula is as follows: odontal therapy (ie, crown lengthening), which would Tooth Proportion = Width divided by Length, which be a contraindication to RSM treatment. should fall in the 75% to 85% range, in order to Class III case types frequently require adjunctive be considered aesthetic. In such instances, the orthodontic and/or periodontal therapies and may clinician must assess where the necessary space can require elective endodontics in borderline cases in order be gained to accomplish the treatment objectives to correct the functional and aesthetic deficiencies. by reducing existing structures rather than shifting the Class IV case types cannot and should not be treated dentition orthodontically. without orthodontic and periodontal consideration (Table). 7 D Vol. 17, No. 1 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page E Kim Table Gingival Considerations Based on Defect Classification Category Amount of Overlap Papilla Height Discrepancy Papilla Shape Distortion Adjunctive Therapy Symmetrical Not Visible None Class I MD < 1 mm BL < 1 mm Class II MD < 1 mm - 2 mm BL < 1 mm < 1mm Not Visible None Class III MD < 1 mm - 2 mm BL < 1 mm - 2 mm 1.5 mm - 2 mm Moderate Consider Periodontal, Orthodontic, and/or Endodontic Class IV MD < 2.5 mm BL < 2 mm > 2 mm Severe Recommended Orthodontic/ Consider Periodontal Space Management Case Classification that required reduction were marked in blue, and red Patients who present with insufficient space and resultant lines were drawn on the incisal edges to indicate the crowding most often require treatment in the mesiodistal ideal restored arch position (form). The free gingival (MD) and buccolingual (BL) direction. Classification is tissue height was also marked to ensure development of categorized into the amount of overlap, as well as papilla the correct gingival architecture. height and shape (Table). Since papilla height discrep- One of the most significant problems when treating ancy is slight in Class I and Class II case types, and the insufficient (crowded) case type is creating natural- papilla shape distortion is not visible, no adjunctive ther- looking gingival architecture. The facially positioned teeth apy is necessary. However, Class III case types frequently present a thin alveolar crest with relatively thin gingival require adjunctive orthodontic and/or periodontal ther- tissue (that is generally positioned apically). It was eas- apies and may require elective endodontics in border- ier and more predictable to move the soft tissues apically line cases to correct functional and aesthetic deficiencies. than to bring them towards a coronal direction. Class IV case types cannot and should not be treated Conversely, if the teeth had been positioned too far lin- without orthodontic and periodontal consideration. gually, as commonly found with an overgrowth of gingival tissue towards the coronal direction, distorted Clinical Procedures for Crowding gingival symmetry would have been observed. In the A 55-year-old male patient presented with moderate-to- majority of these cases, simple gingivectomy would be severe misalignment of teeth #22(33) through #27(43), necessary in order to achieve correct gingival form. along with a preexisting porcelain-fused-to-metal (PFM) The mesiodistal overlaps were marked with blue restoration on tooth #8(11) (Figures 1 and 2). While vertical lines to ensure proper reduction in order to allow teeth #23(32) and #25(41) were positioned facially, subsequent expansion of the restored dental arch (Figure teeth #24(31) and #26(42) were lingually retroclined 4). A buccolingual overlap of approximately 2 mm was and created an uneven overlapping appearance. The evident from one incisal edge to the other (Figure 5). mandibular arch was evaluated in order to ensure devel- A mesiodistal overlap of less than 1 mm was also evi- opment of proper incisal contours. Following impression dent. This borderline Class II/Class III case demonstrated capture, a stone cast was fabricated (Figure 3). Areas some visible distortion in the free gingival height. PPAD E 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page F Practical Procedures & AESTHETIC DENTISTRY Removal of the mesial and distal interproximal areas of the labially positioned tooth was indicated in order to create sufficient space needed to shift the lingually positioned tooth facially. It was critical for the clinicians to decide where to place the facial surface so that a pleasing arch form would be developed. Once the functional waxup was created, an accurate diagnostic waxup was used as the basis for the preparation guide. A red line was drawn on the incisal edge of tooth #23 to indicate the position of the ideal arch form (Figure 5). Using a finishing bur, the laboratory technician cre- Figure 9. The facially positioned teeth were prepared on the stone model using the incisal index as a guide. ated an arch-form preparation guide by preparing each tooth buccally and lingually on the stone model to develop an ideal arch form (Figure 6). This arch-form preparation was given to the clinician as a reference during the clinical tooth preparation phase. A mock-up was then created to allow visualization of the anticipated tooth form (Figure 7). Using condensation silicone putty, an incisal index of the mock-up was made (Figure 8). Pencil lines were drawn on the index to indicate proper spatial relationship as well as width of teeth at the incisal edge. A depth bur was then used in the laboratory to reduce the labially positioned teeth according to the information provided by the incisal index (Figures 9 and 10). The labial index was used by the dentist as a ref- Figure 10. Incisal view of the completed laboratory preparation guide. Note the presence of suggested finishing-line placement. erence guide during tooth reduction and preparation. This guide was also used to indicate the correct final position and help in visualizing the final dimensions of each tooth (Figure 11). Minimal preparation was required on the facial surface to ensure that the lost labial volume would be filled with the porcelain laminate veneer. In order to prevent development of a thick incisal surface, the incisal edge was trimmed lingually. Care was taken to avoid excess reduction and subsequent modification of the finishing line to maintain substantial support for the ceramic material. Once the tooth preparation was completed, an impression was made and sent to the laboratory. A stone model of this impression was poured and checked against F Vol. 17, No. 1 Figure 11. Tooth preparation was initiated according to the predetermined parameters communicated by the labial index. 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page G Kim the incisal index to verify the accuracy of the preparation (Figure 12). The incisal index was used in the laboratory to allow the technician to develop an optimal ceramic buildup (Figure 13). The restorations were fired and characterized as necessary, and the finished restorations were then sent to the dentist for definitive cementation. The definitive restorations were cemented using a composite resin adhesive and cement (Figures 14 and 15). Conclusion RSM is a predictable treatment for many aesthetic and Figure 12. The incisal index was used to help achieve optimal ceramic buildup. functional dental problems. A classification of treatment guidelines is presented as a clinical means to recommend various treatment modalities to ensure aesthetic and restorative success. The RSM case presented herein has replicated the treatment outcomes of orthodontic therapy through the use of aesthetic and restorative techniques. The benefits include correction of tooth shapes and dimensions that result in improved tooth proportions with an aesthetically pleasing appearance. The occlusal relationship has also been remedied to ensure a stable occlusion and proper masticatory function. Figure 13. Care was taken to ensure development of optimal space management during final restoration. Acknowledgement The authors mention their gratitude to Dr. Marc Lowenberg, New York, NY, for his contributions to the clinical case shown herein. References Figure 14. Postoperative appearance of the definitive ceramic restorations following delivery. 1. Brown IS. The effect of orthodontic therapy on certain types of periodontal defects. I. Clinical findings. J Periodontol 1973;44(12):742-756. 2. Ingber JS. Forced eruption: Part II. A method of treating nonrestorable teeth—Periodontal and restorative considerations. J Periodontol 1976;47(4):203-216. 3. Ingber JS. Forced eruption: Alteration of soft tissue cosmetic deformities. Int J Periodont Rest Dent 1989;9(6):416-425. 4. Riedel RA. A review of the retention problem. Angle Orthod 1960;30:179-199. 5. Gürel G. Predictable, precise, and repeatable tooth preparation for porcelain laminate veneers. Pract Proced Aesthet Dent 2003;15(1):17-24. 6. Ward DH. Proportional smile design using the recurring esthetic dental proportion. Dent Clin North Am 2001;45(1):143-154. 7. Ferrari M, Patroni S, Balleri P. Measurement of enamel thickness in relation to reduction for etched laminate veneers. Int J Periodont Rest Dent 1992;12(5):407-413. 8. Preston JD. The golden proportion revisited. J Esthet Dent 1993;5(6):247-251. PPAD G 200501PPAD_Chu.qxd 1/13/05 7:04 PM Page H CONTINUING EDUCATION (CE) EXERCISE NO. X CE X CONTINUING EDUCATION To submit your CE Exercise answers, please use the answer sheet found within the CE Editorial Section of this issue and complete as follows: 1) Identify the article; 2) Place an X in the appropriate box for each question of each exercise; 3) Clip answer sheet from the page and mail it to the CE Department at Montage Media Corporation. For further instructions, please refer to the CE Editorial Section. The 10 multiple-choice questions for this Continuing Education (CE) exercise are based on the article, “Restorative space management: Treatment planning and clinical considerations” by Jason Kim, CDT, MDT, Stephen Chu, DMD, MSD, CDT, MDT, and Galip Gürel, DDS. This article is on pages 000-000. 1. Restorative space management (RSM) alone can be predictably performed in: a. Only Class I case types. b. Only Class II case types. c. Both Class I and Class II case types. d. Neither Class I nor Class II case types. 2. RSM therapy alone can be predictably performed in type III and IV case types. RSM type IV cases can be treated as Class I or Class II postorthodontic treatment. a. The first statement is true, the second statement is false. b. The first statement is false, the second statement is true. c. Both statements are true. d. Both statements are false. 3. Class III case types should consider what type of adjunctive therapy? a. Periodontal. b. Orthodontics. c. Endodontic. d. All of the above. 4. Class IV case types always require: a. Orthodontic therapy. b. Periodontal therapy. c. Endodontic therapy. d. None of the above. 5. Adjunctive orthodontics is a predictable way to alter ____ soft tissue profiles. a. Midfacial. b. Interproximal. c. Both a and b. d. Neither a nor b. H Vol. 17, No. 1 6. RSM can be predictably accomplished without case planning. RSM can be predictably accomplished without a clinically applicable diagnostic waxup. a. The first statement is true, the second statement is false. b. The first statement is false, the second statement is true. c. Both statements are true. d. Both statements are false. 7. A diagnostic waxup with associated preparation guides is recommended in which case types? a. Class I and Class II. b. Class III and Class IV. c. Class I, Class II, and Class III. d. Class I, Class II, Class III, and Class IV. 8. This case type could require tooth mutilation, as well as significant periodontal therapy. a. Class I. b. Class II. c. Class III. d. Class IV. 9. Golden proportion is the ratio between: a. Central and lateral incisors. b. Canines and the first premolar. c. The first and second premolars. d. All of the above. 10. Tooth proportion is defined as: a. Width divided by length. b. Length divided by width. c. Width plus length. d. Length minus width. PPAD H