by Filipe Lopes on REVERSE PET

 

This is a clinical case review detailing this specific procedure for replacing periodontally compromised teeth.

 

Here is a structured synopsis of the contents related to the

REVERSE PET technique described in the video:

 

I. Context and Rationale: Partial Extraction Therapy (PET)

Partial Extraction Therapy (PET) is a category of surgical techniques, including Root Membrane (RM), Socket Shield (SS), and others, designed to preserve the alveolar ridge.

 

• Core Concept:

The key idea is to preserve a portion of the patient’s own root structure and the corresponding periodontal ligament (PDL) complex.

 

• Biological Goal: Maintaining the PDL and associated blood vessels helps prevent the resorption of the buccal bundle bone that typically occurs after conventional tooth extraction.

 

• Aesthetic Challenge: Replacing periodontally compromised teeth with implants is highly challenging, especially in the aesthetic area (like the upper incisors), due to concerns of aesthetic compromise and tissue collapse, particularly when multiple contiguous teeth are involved.

 

 

II. The REVERSE PET (RPET) Technique

REVERSE PET is a novel approach utilizing the principles of PET/RM, specifically designed to overcome difficulties associated with highly mobile teeth, which are often considered a contra-indication for traditional PET.

 

• Definition:

RPET (REVERSE PET) is a procedure where immediate implant placement is combined with the intentional retention of a root fragment.

 

• Key Differentiation:

In RPET, the implant site preparation is performed first.

This is the reverse of other PET procedures where partial root extraction often precedes drilling.

 

• Mechanism:

The implant site preparation is followed by the selective removal (grinding - not extraction) and careful destruction of the remaining root remnants, rather than performing an extraction procedure. This method avoids the risk of accidental extraction or mobilization of the fragment to be left, which is common when attempting partial extraction on highly mobile teeth.

 

III. Clinical Case Summary

The effectiveness of RPET is demonstrated via a clinical case report involving the replacement of four severely compromised upper incisors.

 

• Patient Profile: A 59-year-old female patient with high aesthetic expectations and a chief complaint of mobility, constantly inflamed gingiva, and compromised teeth.

• Initial Condition: The four upper incisors (teeth #7–#10) had Miller mobility indexes (MMI) of 2 or 3, indicating severe periodontal problems.

• Socket Type: CBCT analysis determined the sockets were Type 2B, characterized by the presence of soft tissue but a dehiscence osseous defect involving the middle one-third of the labial bone plate (approximately 7mm to 9mm from the free gingival margin).

• Treatment Plan: Immediate implant placement and simultaneous provisional restoration (IIPP) of all four incisors using RPET. Four implants were planned (one per tooth) to ensure better biomechanical stability and to minimize catastrophic risk if one implant were to fail.

 

IV. Clinical Technique Steps

The procedure used a flapless approach combined with a digital workflow to facilitate same-day immediate provisional restorations.

1. Preparation:

The crown was sectioned down to the marginal gingiva.

 

2. Implant Site Preparation:

Drilling was initiated with a palatal bias to establish the correct 3D position. Drilling proceeded through both the bone and the root, following the regular sequence protocol.

 

3. Primary Stability Strategy:

The drilling sequence was kept one or two burs short of the final size to achieve sufficient primary stability (minimum of 25Ncm insertion torque was required; 40Ncm was sought in this case).

 

4. Selective Root Grinding:

After implant site preparation (which destroys the majority of the root), the remaining root remnants were selectively ground. The coronal part of the root was ground to at least 1mm below the crestal bone level.

 

5. Implant Placement: Implants were placed 1mm to 2mm below the crestal bone level. Ideally, the implant should not touch the root remnants, but contact is acceptable.

 

6. Abutment and Digital Workflow:

Multi-unit abutments (implant extenders) were torqued (30 to 35Ncm). Digital scans were performed, and the provisional restorations (splinted PMMA structure) were delivered within two hours on the same day.

 

7. Final Restoration:

Final splinted restorations were delivered after 4 months.

 

V. Outcomes and Significance

The case report demonstrated the efficacy of RPET in a complex aesthetic scenario.

• Tissue Stability: The technique resulted in stable peri-implant tissues 26 months later.

• Biologic Width Improvement: The technique improved the horizontal component of the biologic width (due to the remaining root shield) and the vertical component (via the implant extender concept, "one abutment one time" and the "bio-block concept").

• Clinical Benefits:

RPET offers fewer appointments, reduced overall treatment time, maintenance of the gingival architecture, and significantly reduced patient morbidity due to the flapless approach and immediate provisionals.

 

• Paradigm Shift:

This technique represents a shift from the conventional, delayed approach (requiring extraction, healing, implant placement, healing, etc.) often warranted for consecutive Type 2 defects in the aesthetic area, which typically results in extensive tissue collapse.

 

 

The success of the Partial Extraction Therapy concepts, like REVERSE PET, in maintaining ridge dimension is akin to leaving the foundation walls (the retained root segment) of a house intact when replacing the central support beam (the implant). By maintaining the foundation where the original structure (the PDL) was anchored, the surrounding soil and contours (the soft and hard tissues) are prevented from collapsing inward, thus preserving the natural aesthetic profile.