Abstract
The Biologically Oriented Preparation Technique (BOPT) is a vertical crown preparation concept that combines tooth preparation without a conventional horizontal finish line with controlled intrasulcular instrumentation and immediate provisionalization.
Unlike traditional crown preparations, BOPT does not rely on a defined chamfer or shoulder to determine the restoration margin. Instead, a vertical cervical preparation is created, and the provisional restoration establishes a new prosthetic emergence profile that guides subsequent soft-tissue healing and maturation.
Flame-shaped diamond burs are particularly suited to this technique because their tapered geometry can support proximal access, axial reduction, cervical preparation and progressive surface refinement.
This article describes a practical BOPT workflow using the MR.BUR Flame Coarse Diamond Bur FG, Fine Grit Pre-Polishing Flame Diamond Bur FG and Super Fine Finishing Flame Diamond Bur FG, while emphasizing periodontal assessment, bur angulation, gingitage and provisional restoration design.
Introduction
BOPT, or Biologically Oriented Preparation Technique, was introduced internationally by Loi and Di Felice (2013) as a prosthetic approach based on vertical tooth preparation without a conventional finish line.
Loi, Caivano and Rodríguez describe BOPT as more than simply removing the cervical margin. The technique combines finish-line-free preparation, controlled gingitage and immediate placement of a provisional crown. The shape of the provisional restoration then contributes to the new emergence profile and surrounding soft-tissue architecture.
This concept is based on what the authors call the “dominance of shapes”: changing the transmucosal contour of a restoration can influence the form of the surrounding tissue. For this reason, BOPT preparation and provisionalization should be regarded as a single restorative workflow rather than separate procedures.
What Is BOPT Vertical Crown Preparation?
Conventional crown preparation normally creates a horizontal cervical reference such as a chamfer or shoulder.
In BOPT, this horizontal finish line is eliminated. The cervical tooth surface is prepared vertically, allowing the clinician and technician to determine the restorative emergence profile within the prepared zone.
At the same time, controlled instrumentation within the sulcus de-epithelializes its internal surface, a process referred to as gingitage. The immediate provisional restoration is then shaped and polished to support the blood clot and guide soft-tissue healing.
Loi, Caivano and Rodríguez emphasize that the provisional restoration is a fundamental component of the BOPT technique.
Why Are Flame Diamond Burs Used in BOPT?
The flame shape is well suited to BOPT vertical crown preparation because its narrow tip can access proximal and cervical areas, while the tapered diamond surface can follow the axial wall of the prepared tooth.
The original BOPT clinical protocol also describes a progression from coarser to progressively finer diamond particles during preparation and finishing.
For an MR.BUR workflow, this principle can be translated into a three-stage flame bur sequence.
MR.BUR Flame Bur Sequence for BOPT
| Stage | MR.BUR Instrument | Clinical Role |
|---|---|---|
| Initial Preparation | Flame Coarse Diamond Bur FG – Green Band | Proximal access, axial reduction and establishment of the vertical preparation |
| Refinement | Fine Grit Pre-Polishing Flame Diamond Bur FG – Red Band | Refines axial and cervical surfaces while maintaining the established preparation geometry |
| Final Finishing | Super Fine Finishing Flame Diamond Bur FG – Yellow Band | Reduces surface irregularities and refines the final vertical preparation |
The MR.BUR sequence progresses from coarse reduction to fine refinement and super-fine finishing.
The Flame Coarse Diamond Bur is used during the initial cutting stage, while the Fine Grit Flame Bur provides greater control during axial and cervical refinement. The Super Fine Flame Bur is used during the final finishing stage to improve surface smoothness without unnecessarily changing the established vertical geometry.
All three are friction-grip instruments intended for use with a high-speed handpiece under adequate water cooling.
Clinical Workflow for BOPT Vertical Crown Preparation
1. Diagnostic Planning and Provisional Preparation
Before tooth preparation begins, the final prosthetic contour should be considered through diagnostic planning or a wax-up.
The BOPT protocol described by Loi and colleagues begins with an eggshell provisional crown prepared before the clinical cutting stage. Its cervical portion should reach or align with the gingival margin so that it can later be rebased and shaped into the desired emergence profile.
Periodontal health, sulcus depth, tooth position, existing restorations, available tooth structure and the planned restorative material should also be evaluated before preparation.
2. Perform Intrasulcular Mapping
Following local anaesthesia, the gingival sulcus is probed before subgingival preparation.
Loi, Caivano and Rodríguez describe this process as intrasulcular mapping. Its purpose is to understand the depth and anatomical variation of the sulcus rather than introducing the bur subgingivally without a clinical reference.
This assessment helps guide the subsequent cervical preparation and provides the clinician with a reference for controlled intrasulcular instrumentation.
3. Begin with Supragingival Preparation
The natural tooth or existing abutment is initially prepared above the gingival level.
A simplified clinical sequence based on the original BOPT protocol is:
Proximal access → Incisal/occlusal reduction → Tilted axial preparation → Facial and palatal/lingual reduction
The MR.BUR Flame Coarse Diamond Bur FG – Green Band may be used during these initial preparation stages when its geometry corresponds to the clinical area being reduced.
The objective is controlled anatomical reduction rather than indiscriminate removal of tooth structure.
Adequate water cooling, light pressure and a stable finger rest should be maintained throughout the procedure.
4. Establish the Vertical Cervical Preparation
Following supragingival reduction, the preparation progresses toward the cervical region.
Instead of creating a shoulder or chamfer, the flame bur removes the existing cervical finish line and establishes a continuous vertical preparation area.
Bur angulation is particularly important during this stage. The BOPT protocol follows the principles of tilted preparation rather than simply directing the bur vertically and apically from the beginning.
The preparation should gradually transition from the axial surface toward the cervical zone while maintaining control over convergence and tooth reduction.
5. Subgingival Preparation and Gingitage
Once the supragingival portion has been completed, the flame diamond bur is progressively introduced into the cervical zone according to the previously mapped sulcus.
During this stage, the primary objective is controlled subgingival preparation of the tooth. Gingitage occurs simultaneously as the internal sulcular epithelium is de-epithelialized by controlled rotary instrumentation.
The preparation is continued circumferentially while carefully controlling bur position and angulation.
A key principle emphasized by Loi and colleagues is that transmucosal steps should not remain after preparation. An irregular cervical transition or residual horizontal step may interfere with the intended vertical BOPT geometry.
6. Refine and Finish the Preparation
Once the vertical preparation form has been established, progressively finer MR.BUR flame diamond burs can be introduced.
The MR.BUR Fine Grit Pre-Polishing Flame Diamond Bur FG – Red Band may be used to refine the axial and cervical surfaces while reducing the deeper surface marks left by the initial coarse preparation.
The objective is refinement rather than further bulk reduction. The established cervical geometry and convergence should be preserved.
The MR.BUR Super Fine Finishing Flame Diamond Bur FG – Yellow Band can then be used for final surface refinement.
The complete bur progression can be summarized as:
Coarse Reduction → Fine Refinement → Super-Fine Finishing
The aim is to progressively improve surface quality while maintaining the established vertical preparation geometry, controlled convergence and smooth cervical transition.
Why the Provisional Crown Matters in BOPT
BOPT is not complete when the bur leaves the tooth.
After preparation, the provisional crown is rebased and reshaped to establish the desired prosthetic emergence profile. Loi and colleagues describe the provisional restoration as a scaffold that contributes to soft-tissue healing and maturation.
Its cervical contour should therefore be carefully shaped and meticulously polished before cementation.
In the original BOPT protocol, the provisional margin is maintained within approximately 0.5 mm subgingivally, and the restoration is generally left undisturbed for at least four weeks when tissue healing is progressing appropriately.
During this period, the surrounding gingival tissues can adapt to the new emergence profile.
If modification of the gingival position is required, the contour of the provisional restoration may subsequently be adjusted to influence the available cervical space before the definitive restoration is produced.
Common Clinical Errors to Avoid
Leaving a Horizontal Cervical Step
BOPT is based on a continuous vertical cervical preparation. Residual shoulders, chamfers or transmucosal steps may interfere with the intended preparation geometry.
Forcing the Bur Deep into the Sulcus
Subgingival preparation should follow prior intrasulcular mapping and controlled bur orientation. Uncontrolled apical pressure may produce excessive tooth reduction, cervical grooves or unnecessary soft-tissue trauma.
Excessive Reduction During Finishing
Fine and super-fine flame burs should refine the preparation rather than substantially change its geometry. Excessive finishing may unintentionally widen or over-taper the preparation.
Ignoring the Provisional Restoration
The provisional restoration is an essential part of BOPT. Preparation alone does not establish the final emergence profile or guide the subsequent soft-tissue response.
Discussion
BOPT differs from conventional crown preparation because its clinical result depends on the relationship between vertical tooth preparation, gingitage and the restorative emergence profile.
Flame diamond burs are useful because their narrow and tapered geometry can participate in proximal access, axial reduction, cervical preparation and final finishing.
However, the bur itself does not determine the biological outcome.
The original BOPT authors emphasize the importance of periodontal assessment, correct bur inclination, elimination of cervical steps, immediate provisionalization and meticulous polishing of the restoration.
Histological observations reported by Rodríguez and colleagues have also suggested connective-tissue attachment changes following BOPT treatment, although additional research is still required to establish the biological effects of the technique more conclusively.
The MR.BUR Flame Coarse, Fine Grit and Super Fine Diamond Bur FG ranges can support the mechanical stages of the BOPT workflow through initial cutting, controlled refinement and final finishing.
Published BOPT studies, however, did not specifically evaluate or endorse MR.BUR products.
Conclusion
BOPT vertical crown preparation is more than a crown preparation without a finish line. It combines vertical tooth reduction, controlled subgingival instrumentation, gingitage and immediate provisionalization to establish a new restorative emergence profile.
A practical MR.BUR bur progression for the preparation can follow:
MR.BUR Flame Coarse → Fine Grit Flame → Super Fine Flame
The Flame Coarse Diamond Bur establishes the initial preparation, the Fine Grit Flame Bur refines the cervical and axial surfaces, and the Super Fine Flame Bur completes the final finishing stage.
Successful BOPT still depends on periodontal assessment, intrasulcular mapping, controlled bur angulation, adequate water cooling, smooth vertical preparation and carefully designed provisional restorations.
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