|Year : 2012 | Volume
| Issue : 1 | Page : 38-40
Management of an abutment with less clinical crown height by preserving biological width through an interdisciplinary approach
Senny Thomas Parackal1, Majo Ambooken2, Jose Jullian3, Robin James Pellissery4
1 Department of Periodontics, Al Azhar Dental College, Thodupuzha, Kerala, India
2 Department of Periodontics, Mar Baselios Dental College, Kothamangalam, Kerala, India
3 Department of Prosthodontics, Mar Baselios Dental College, Kothamangalam, Kerala, India
4 Department of Conservative Dentistry and Endodontics, Indira Gandhi Institute of Dental Science, Kothamangalam, Kerala, India
|Date of Web Publication||22-Mar-2012|
Senny Thomas Parackal
Department of Periodontics, Al Azhar Dental College, Thodupuzha, Kerala
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The success of fixed partial dentures and crowns depends to a great extent on the prevention of infringement of the biological width. This case report discusses a crown-lengthening procedure that permits successful placement of prosthesis with good prognosis, by preservation of the biologic width. This article also reviews the various aspects of crown lengthening, highlighting the importance of comprehensive treatment planning with an interdisciplinary approach.
Keywords: Biological width, crown lengthening, interdisciplinary approach
|How to cite this article:|
Parackal ST, Ambooken M, Jullian J, Pellissery RJ. Management of an abutment with less clinical crown height by preserving biological width through an interdisciplinary approach. J Interdiscip Dentistry 2012;2:38-40
|How to cite this URL:|
Parackal ST, Ambooken M, Jullian J, Pellissery RJ. Management of an abutment with less clinical crown height by preserving biological width through an interdisciplinary approach. J Interdiscip Dentistry [serial online] 2012 [cited 2020 Jun 2];2:38-40. Available from: http://www.jidonline.com/text.asp?2012/2/1/38/94191
| Introduction|| |
Fixed prosthodontic treatment has become an integral part of dental practice where patient comfort and aesthetics are quite essential. Success of a fixed partial denture largely depends on how efficiently the biological width is preserved. Biological width is the physiologic dimension of the junctional epithelium and the connective tissue attachment. Infringement of biological width by placement of a restoration within its zone may result in gingival inflammation, pocket formation, abscess formation and alveolar bone loss. Hence in a tooth with short clinical crown periodontal intervention, namely crown lengthening is important and crucial for long-term prognosis of the abutment tooth.
| Case Report|| |
A 23-year-old female patient was referred from the department of prosthodontics with a very short clinical crown and less interocclusal space to accommodate the pontic of fixed partial denture [Figure 1]a. On examination, crown structure of 34, 35, 38 was considered inadequate for prosthetic crown preparation and inter occlusal distance was very less to accommodate a pontic. Our treatment plan included an endodontic treatment of 38, since there was pulpal involvement, intentional RCT of abutment teeth (34, 35) and a flap surgery with osteoplasty/osteotomy. As the sulcus depth was 2 mm (with no pockets present), decision was made to perform osseous resection and recontouring. The surgical procedure was carried out as follows: Internal bevel incision in relation to the teeth continued as two parallel incisions on the crest of edentulous area were given. Thin strip of gingiva between the parallel incisions and the secondary flap were removed and then primary flap was elevated [Figure 1]b. Osseous reduction of the crest of the alveolus was done to increase the inter occlusal distance and ostectomy in relation to 34, 35 and 38 to increase the clinical crown height with sufficient area for biologic width attachment flap was closed at more apical level with respect to the cemento-enamel junction of the adjacent tooth. Sutures were removed after one week.
After surgery there was sufficient inter occlusal space for a pontic and supra crown structure was sufficient for restoration with a prosthesis [Figure 2]a. Fixed partial denture was fabricated and delivered after six months. Patient was followed up for three years and results appeared to be satisfactory without any pocket or inflammation around the prosthesis [Figure 2]b.
|Figure 1: (a) Inadequate clinical crown of 34, 35, and 38 for crown preparation and less inter occlusal space to accommodate pontic. (b) Internal bevel incision of abutment teeth was continued as two parallel incisions on the crest of edentulous area and tissues between these parallel incisions were removed. Osseous reduction on the crest of the alveolus was done to increase the interocclusal space and ostectomy in relation to 34, 35 and 38 to increase the clinical crown height. Sufficient area was also provided on crown to accommodate minimal dimension of biologic width|
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|Figure 2: (a) Review after 2 weeks - healing was satisfactory and supra crown structure was sufficient for restoration with prosthesis. (b) Fixed partial denture fabricated and delivered after 6 months. A healthy collar of gingiva established without breaching biological width and attached gingiva|
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| Discussion|| |
There is currently a strong need for fixed prosthodontic restorations in dental practice. Before fixed prosthodontic treatment periodontal evaluation is a must and is a 'sine quo non' for restorative dentistry. The periodontal structures should be preserved during tooth preparation and it must provide a sufficient space to establish a healthy, long lasting and esthetic restoration.
Before proceeding with tooth preparation of a carious, fractured tooth, status of the clinical crown should be considered first. If it is short, it requires crown lengthening by restorative build up or extension of gingival margin apically by periodontal surgical means. Ideally for posterior tooth rehabilitation, the recommended dimensions are as follows; 
Minimum thickness of crown material on occlusal surface = 2 mm
Minimum abutment height = 4-5 mm
Sulcus depth = 2 mm
Biological width = 3 mm
If these minimal length and dimensions are not there, we should think of restoring these dimensions with effective steps to develop a healthy and a long standing restoration. Crown lengthening is one of the effective and predictable procedures done before prosthetic and restorative treatment.
Objectives of crown lengthening include  removal of subgingival caries, preservation and maintenance of restorations, cosmetic improvement, enabling restorative treatment without impinging biological width, correction of occlusal plane and facilitation of improved oral hygiene.
In crown-lengthening procedure, the periodontal tissue is assessed carefully and the clinical crown is lengthened apically with an intentional calculated attachment loss. Sufficient amount of residual alveolar bone and minimum required width of attached gingiva are prerequisites before this treatment. ,
According to the observation of Gargiulo (1961), gingival connective tissue attachment occupies 1.07 mm and junctional epithelium occupies another 0.97 mm coronal to alveolar bone. A combination of these two measurements constitutes the biological width. 
Location of the osseous crest in relation to the gingival margin and future restorative margin is the most critical reference point for both the periodontist and restorative prosthetic dentist.  In order to prevent violation of the biological width during intra crevicular tooth preparation, assessment of the following parameters is recommended:  anatomic crown relationship of CEJ and bone crest, measurement of the zone of attached gingiva, the presence of pocket.
As the first step the anatomical relationship of the bone with respect to the gingival margin is assessed. This can be made out by sounding or transgingival probing (inserting the probe forcefully through the gingival sulcus towards the crest of alveolar bone under local anesthesia). Transgingival probing also helps to determine the relationship of gingival crest to CEJ. The location of these anatomical landmarks will indicate whether there is gingival excess or normal gingival width. The surgical intervention for correcting any discrepancy is based on four criteria namely pocket depth, width of attached gingiva, level of alveolar bone with respect to the gingival margin and additional crown length required. 
Decision making during surgery 
Definitive crown preparation should not be made for at least three months after surgery and sometimes when the periodontal biotype is thin, not before six months.  The biological width will reestablish to its original vertical dimension by six months following surgery.  After surgery it is even more important for the restorative dentist to use the osseous crest as a reference point during crown preparation and to always follow the scallop of the free gingival margin. 
- If the pocket depth is more than 4 mm with sufficient amount of attached gingiva, simple gingivectomy is indicated.
- If pocket more than 4 mm is present with minimal attached gingiva, apically positioned flap is indicated.
- In case of short clinical crown with no pockets and a sufficiently attached gingiva, flap surgery (internal bevel gingivectomy) and osteoplasty is indicated.
| Conclusion|| |
Long-term success of all restorations and prostheses depends on the preservation of biologic width. A case of short clinical crown length can be successfully restored by crown lengthening and placement of a prosthesis that does not encroach the biologic width. In such cases high prognostic value of the treatment can be achieved by an interdisciplinary treatment approach.
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[Figure 1], [Figure 2]