“BOPT”- A MODERN CONCEPT IN TOOTH PREPARATION FOR ALL CERAMIC RESTORATION
Gingival tissue stability around fixed prosthetic restorations is one of the most demanding objectives for dentists. One of the main clinical complications in fixed prosthodontics on natural teeth is the unsatisfactory esthetic result due to the apical migration of the gingival margin. The tendency of the gingival margin to migrate apically in time, is related to different factors: Inadequate quality and quantity of keratinized gingiva (thin biotypes are more likely to have recessions), reaction to a trauma during prosthetic work (preparation, gingival retraction), chronic inflammation due to prosthetic errors (technical problems like open margins, violation of the biological width, horizontal overcontour), trauma due to inadequate tooth brushing1,2. Among factors related to restorative procedures one is particularly relevant: preparation technique and the corresponding geometry of the finish line. Traditionally, there are two types of dental preparations: preparations with finishing lines, also called horizontal; and preparations without finishing lines, described as feather edge 3. The preparation technique without a finish line is also known as the Biologically Oriented Preparation Technique (BOPT). In this protocol, the crown’s anatomic emergence profile at the Cemento Enamel Junction (CEJ) is eliminated with diamond rotary instruments to create a new prosthetic junction, adapted to the gingival margin. The aim of this protocol is to create a new anatomic crown with a prosthetic emergence profile that simulates the shape of the natural tooth 4.This clinical report describes management of a case of endodontically treated maxillary anterior tooth with BOPT.
18 year old female kabbadi player reported to Dept of Prosthodontics ADC R with chief complaint of broken upper front teeth resulting in an unesthetic smile. On presentation of history it was elicited the current clinical condition secondary to sports injury. Medical history didn’t reflect any relevant findings. In past dental history, patient reported endodontic treatment for 11 and light cure composite restoration for 21 four months back. Intraoral examination showed full complement of teeth with good general periodontal health. Examination of maxillary anterior region showed Ellis class III fracture with respect to 11 and discolored composite restoration wrt 21 (fig 1). Radiological evaluation revealed 11 with well obturated root canal without any periapical lesion. Treatment plan formulated included all ceramic restoration for 11 with BOPT technique and correction of light cure composite restoration for 21.
Description of technique
This includes intrasulcular mapping to assess epithelial attachment level with the help of periodontal probe (Fig 2). Conventional supragingival preparation was done which involves tooth preparation in the same manner as usually done in conventional tooth preparation for all ceramic which involves labial and lingual reduction of 1.2-1.5mm followed by incisal reduction of 2mm using a diamond flame shaped bur (Shofu Dental, Japan). Then the intrasulcular preparation is started by entering the sulcus with the bur tilted obliquely, so that it cuts with its belly and not with the tip, working at the same time on the tooth and gingiva (gingitage technique) and connecting this preparation plane with the axial one, into a single and even vertical surface (finishing area). In this way, the existing CEJ is erased and in prepared teeth, the same is done with existing finishing lines. In BOPT gingitage technique (Fig 3) was used to eliminate the emerging component of the dental anatomy or any pre-existing preparation margin. This will allow the creation of a finish area within which the crown margin can be moved coronally. The final step of the preparation is refining the entire surface with a 20-micron diamond bur to smooth out the surface.
Temporary crown relining
This steps includes temporization which is a very important part of the technique. A hollowed acrylic crown (prefabricated using indirect technique) with a contour that follows the gingival margin is prepared which is checked for its ?t, this temporary crown is relined with autopolymerising poly methyl methacrylate acrylic resin (DPI, India) directly in the mouth. Once it has set, the crown shows two distinct margins: a thin internal one, which records the intrasulcular part of the prepared tooth, while the thicker external one follows the external portion of the gingival margin. The space between the two margins is the negative image of the gingiva (Fig 4)
The space between the two portions is ?lled with a light cured ?owable composite resin (3M, Germany) to thicken the coronal margin and allow the creation of the crown contour. This is done to produce a new angular component which will be formed together with a new CEJ that will be positioned in the sulcus, no deeper than 0.5 to 1 mm, fully respecting the biologic width (controlled invasion of the gingival sulcus). After polishing, the crown was cemented and the excess cement material removed. The intrasulcular portion of the temporary crown’s margin will support the gingival margin circumferentially, allowing the clot stabilization into a fully structured gingival tissue (clot preservation). The healing process determines the reattachment and thickening of the gingival tissue, which will mold and adapt to the new emergence pro?le 4,5.
After a minimum of 4 weeks, when the gingival tissue is stabilized and final impression was made with addition silicone impression material(3M. Germany) using putty light body technique and poured with Type IV dental stone( DPI,India). Before the final impression, the light cure composite restoration of 21 was rectified with proper contour and shade.
The most critical step in final restoration includes laboratory procedure to accurately read and replicate the margins of preparation as there are no distinct finish lines. Since an improved control over the gingival levels is needed before exposing the ?nishing area, a black mark is traced with a 0.5 mm pencil over the gingival contour projecting it on the abutment’s wall (black line). Afterwards, the gingival part around the abutment is removed, showing the subgingival area of the preparation reproduced on the model (Fig 5). The apical part of the model is exposed and it will be marked with a blue line. The area between the two lines is the “?nishing area” and the “?nishing line” for the restoration is marked with a red pencil, on which will fall the margin of the restoration. The position of the margins of the restoration depends on the depth of the sulcus and on the esthetic needs, keeping in mind that the crown margin will never invade the epithelial attachment. The red line becomes the reference margin for the ditching process. As for the concept of BOPT it is said that the gingival pro?le will adapt to emergence pro?le of the restoration rather than the restoration being shaped according to gingival contours. Hence restoration is fabricated on the master cast without the gingival component, creating a morphofunctional and esthetic ideal contour. The prosthetic restoration is then transferred on to the model with the gingiva to evaluate the contours tridimensionally. The final restoration is cemented and excess cement removed well-modulated esthetic restoration is the final outcome (Fig 6). Post op evaluation showed marked difference when compared to pre op (Fig:7)
Gingiva is that part of oral mucosa that covers the alveolar process of the jaws and surrounds the neck of teeth in a collar like fashion. Anatomically gingiva is divided in to marginal, attached and interdental gingiva. Marginal gingiva is the border of teeth surrounding the teeth in the collar like fashion. It is demarcated from attached gingiva from free gingival groove. Attached gingiva is firm, resilient and tightly bound to underlying periosteum. Histologically gingiva have Junctional epithelium (JE), sulcular epithelium (SE) and oral epithelium (OE). JE is a stratified squamous non keratinizing epithelium and its thickness varies from 3-4 layers in early life5. According to the Gargiulo, Went & Orban, biological width (2.04 mm) is the combination of epithelial attachment (junctional epithelium) and the connective tissue attachment 6. Whenever there is encroachment of biological width, the first and foremost reaction is inflammation which further progresses to form pocket formation which eventually leads to periodontitis. Hence it is important to respect biological width when planning for restoration so as to avoid these conditions6.
On the basis of location finish lines were of two types supragingival and subgingival finish lines. Conventionally supragingival finish lines were used in most cases but subgingival finish line was also used in conditions such as superior esthetics, presence of existing restorations extending subgingivally, insufficient vertical length for retention and patients with high caries index7.
Biologically Oriented Prepataion Technique (BOPT) has been popularized by by Dr Ignazio Loi after 15 years of research, and then published it in 2013 in European journal of esthetic dentistry. He advocated this technique using feather edge finish line with the aim to create new anatomic crown with a prosthetic emergence profile simulating natural tooth8.
Advantages of this technique includes preservation of tooth structure, emergence profile and excellent esthetics. The other fundamental concept is that the ?nish line of horizontal preparations is located on the prepared tooth, while the ?nish line is the prosthetic crown’s margin itself in the BOPT technique with no distinct margin hence the margin can be shortened or extended both in the temporary or ?nal restoration at different intrasulcular levels, without harming the quality of ?t and without invading the epithelial attachment because the ?nish area is always located above it (controlled invasion of the gingival sulcus). With the BOPT technique it is possible to transfer the emergent anatomy to the prosthetic crown. This allows a free interaction with the gingiva that will adapt, shape and settle forming new forms and pro?les. In the BOPT technique, interaction between preparation restoration & gingiva, enables the gingiva to thicken and to adapt to new forms, resulting in increased stability both in the short and in the long term9.
BOPT technique has proven successful in maintaining stability of percoronal soft tissues, in natural teeth. With the BOPT technique, it is possible to interact with the surrounding tissues modifying their shape and scalloped architecture regardless of any preexisting dental or gingival limitation. The advantages are relevant considering that most of the clinical results are obtained only through the restoration itself, both provisional and ?nal (margin position, emerging pro?le, tooth form). This is a novel and innovated technique which is an integration of newer technology with the classical concepts yielding promising outcomes in future. However more studies are required in future on this technique.
TAKE HOME POINTS
· This technique involves gingival modulation along with preservation of tooth structure which enhance the emergence profile.
· The possibility to position the final finish line at different levels, either more coronally or more apically, within the gingival sulcus (controlled invasion of sulcus), without affecting the quality of marginal adaptation of the restoration.
1. Valderhaug J. Periodontal condition and carious lesion following the insertion of ?xed prosthesis: a 10-years follow-up study. Int Dental Journal 1980;30:296–304.
2. Valderhaug J, Birkeland M. Periodontal conditions in patients 5 years following insertion of ?xed prostheses. J Oral Rehab 1976;3:237– 243.
3. Ingraham R, Sochat P, Hansing FJ. Rotary gingival curettage: A technique for tooth preparation and management of the gingival sulcus for impression taking. Int J Periodont Rest Dent 1981;1:9–33.
4. Loi I. Protesi su denti naturali nei settori di rilevanza estetica con tecnica BOPT: Case series report. Dental Cadmos 2008;76:51–59.
5. Newman MG, Takei H, Klokkevold PR, Carranza FA. Carranza’s Clinical Periodontology, 12th Edition. 2015: pg 15-17.
6. Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans. J Periodontol 1961;32:261-7.
7. Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. 2nd ed. St. Louis: Mosby-Year Book; 1995. p. 137-8.
8. Loi I, Felice AD. Biollogically Oriented Preparation Technique (BOPT): a new approach for prosthetic restoration of periodontally healthy teeth. Eur J Esthet Dent. 2013 Spring;8(1):10-23.
9. Panadero RA, Ruiz FM. Vertical preparation for fixed prosthesis rehabilitation in the anterior sector. October 2015; 114(4):474–8.
Fig: 7 Pre Op vs Post Op