June 10, 2019
by Preety Desai, BSc, DDS, Dip. Periodontics, MSc Laser Dentistry
Dentists are bombarded with numerous products from our dental suppliers’ trying to sell us on the fantasy of an “atraumatic tooth extraction”, promising to improve on what we were taught in dental school. This is all in an effort to benefit our practice and the patient’s future implant site. It is our responsibility to educate ourselves and revisit the current literature on the art of extraction techniques, based on science.
Dental distributors continuously promote the sale of various devices and surgical instruments for the purpose of extractions in an “atraumatic manner”, and yet there is nothing atraumatic about the extraction of a body part, whether it is in a flapped or flapless manner.
All the techniques currently being promoted discuss the removal of the root by enabling the expansion of the alveolar socket for root removal without root tip fractures. The alveolar socket is what gives way and expands, regardless of whether it is a periotome gently expanding the facial plate, the intraoral extrusion “pulling” on the root as it is being elevated, or “bracing” forceps on the buccal plate enabling the root to “organically torque” out of the socket… all these methodologies are scientifically and biologically flawed in our expectations of the procedure and the results achieved. From the remaining alveolar socket’s point of view, it is the bone that had to give way in order for the root (which has been deemed hopeless) to be extracted. It is the remaining bone which has been expanded, drilled away and heated up in order to remove a hopeless tooth. It is this precious buccal plate which we are not only trying to maintain, but also not to touch, in order to provide a foundation for our socket grafting and our future implant site. Should it not be the complete reversal?
Extraction techniques are taught in dental schools based on the instructor’s experience and training in an apprentice type approach; and yet the literature on the actual extraction technique during the 1940’s and 1950’s was based on impacted teeth (i.e. primarily the third molars) and complications of access, sectioning and lack of damage to the surrounding anatomy and tissues. Although, the research papers around that time encompassed the entire gamut of post-operative complications: hemorrhage, aspiration of roots, sinus fenestrations and more, nothing was deemed problematic until the introduction of the endosseous implants. The repercussions of the resorbed socket in three dimensions, which fundamentally negates the possibility of a restoratively driven implant placement into the partially edentulous mouth, are huge.1 Only recently, we finally realize the vitality of over-engineering the extraction socket in order to compensate for the 30-40% socket resorption, which we have come to accept as the norm10,12 within the first three months post extraction. In the esthetic zone, the importance of maintaining adequate ridge volume for a long-term esthetically acceptable implant-supported prosthesis becomes even more vital.2
Today, tooth extraction cannot be perceived purely as tooth loss, without critical alterations to the adjacent hard and soft tissues. The process of local changes which occur in order to close the wound and restore tissue homeostasis is called “socket healing”. Tooth extraction was once described as “tissue amputation” that may lead to functional, psychological, postural and local changes”.3
The question then remains, does anything we do, as far as our actual “atraumatic extraction technique”, counteract the amount of normal resorption that seems to be genetically dictated by our bodies when we have to lose a tooth? In 1969, Amler first described extraction site remodeling,4 but today we can better understand the vital importance of the embryological basis of the alveolar process in order to interpret and navigate the 21st century extraction technique, which must be truly “minimally invasive”.
In 2011, a study described 250 CBCT’s of the maxillary anterior teeth with respect to the dimensions of the alveolar process in relation to the coronal, mid-buccal and apical thickness of the alveolar plate.5 Facial plate thickness was <1mm (average ~0.5mm), while 50% of sites were <0.5mm. What does this mean histologically? The bundle bone (the alveolar bone proper) is lamellar bone (0.2-0.4mm in thickness) and is layered circumferentially in 360’ around the root, while the alveolar bone is also concentric but has marrow spaces. The periodontal ligament (PDL) connects the root to the bundle bone (via Sharpey’s fibres’ insertion into cementum) and to the alveolar socket (marrow spaces). What we must realize is that, bundle bone is a tooth dependent structure, same as dentinal root cementum and the PDL. Some degree of dimensional change post extraction will happen 100% of the time regardless of the technique employed. Our charge, as clinicians is to paradigm shift our expectations of the role of the remaining buccal plate. We must ensure to use THE MOST minimally invasive technique possible for the extraction in order to not only retain all the bundle bone, but also to avoid inadvertent pressure on it, which would enhance its resorption.10
THE TECHNIQUE INVOLVES 5 SIMPLE STEPS
– Full thickness flap exposes the full buccal plate in order to visualize the extent of any dehiscence or fenestration of the buccal plate (Figs. 1 & 2).
– Decapitate the crown of the tooth or relieve the mesial-distal contacts (if still in contact) thus occlusally visualizing the root’s anatomy and all its curvatures (Fig. 4).
– Circumferentially use the laser tip as a periotome angled 30’ towards the root and remove the root dentin in a methodical and precise fashion along the PDL area. The laser ablation of the dentin follows down to 6-8mm into the socket – ablating each root independently and sequentially (Fig. 4).
– The gap between the mesial/distal socket walls and the ablated root, allows purchase point of the micro-elevator, elevating each root only mesio-distally with only finger pressure – no pressure against the buccal plate due to the root dentin having been removed from the buccal plate – each root organically elevates at its own path of least resistance. In the case of MINIE extraction, the root is relieved of resistance on the buccal aspect and thus elevates easily without touching the buccal plate (Fig. 5).
– Remaining socket/s are then curettaged with laser energy, removing infected granulation tissue tags, and PDL remnants and penetrating into alveolar socket walls, ablating any remaining pathogens to a depth of 2.5-3 μm for the Er,Cr:YSGG laser and 0.5 μm for the Er:YAG laser (Fig. 6).
– All four walls of socket then enable socket grafting, particulate bone containment and membrane draping (Fig. 7).
– Four months later, flap elevation showed buccal profile has resorbed 30% as expected but graft containment at time of extraction enabled stability and bone remodeling and mineralization, so that at four months adequate torque for implant placement is possible (Figs. 8-11).
– Two years later, post extraction shows adequate hard and soft tissue foundation for good home care by patient, avoids plaque and smear layer accumulation, reducing risks of peri-implantitis (Figs. 12-15).
The extracted socket resorbs more in the horizontal vs vertical dimension but its vertical dimension is much more difficult to re-establish.4 We should expect that up to 50% reduction of the original ridge width will occur, and bone resorption will be greater at the buccal aspect vs palatal, and a larger amount of alveolar bone reduction will take place in the molar regions.6,7 The extraction socket is considered healed once epithelialization of the occlusal aspect is completed (10-20 weeks), all dependent on the individuals’ healing capacity, but also on surgical trauma during the extraction. Radiographic bone fill can occur 6-9 months post extraction organically without bone grafting.
The three phases of socket healing occur sequentially after an extraction: inflammatory, proliferative and bone remodeling. The inflammatory phase is key to the formation and stabilization of the initial blood clot in the socket, leading to osteoid formation and eventually bone. The most stable blood clot is formed when it is protected in 3 dimensions (i.e. a 4-walled defect). This explains our focus in the periodontal literature on the improved success of guided tissue regeneration in 3-walled defects, when the bone graft and blood clot can be stabilized better with an overlying collagen membrane. If we take a leap of understanding from the success of GTR in 3-walled defects and apply it to the extraction socket and its imminently resorbing buccal wall; we can agree that the best clot stabilization is by a rigid bony wall and not by a man-made collagen membrane on the buccal aspect.
Schropp8 biopsied resorbing socket walls and showed that a few weeks after tooth removal, osteoclasts were found to be localized around buccal and lingual socket walls at the occlusal crests and on the outer and inner (bundle bone) portions of the socket. Even though bony remodeling takes place equally on buccal and lingual aspects, the lingual bone is usually thicker than the buccal and thus remodeling results in greater vertical bone loss at the thin buccal plate vs thicker lingual aspect. In addition, bone resorption takes place earlier than bone reformation, thus two-thirds of the resorption process occurs in the first three months of healing. Now we understand histologically that the “alveolar bone proper” WILL resorb in three months, and so, perhaps, we can change our expectation of the buccal plate from providing the “permanent walls of support” to that of a slow “resorbing” membrane providing scaffolding for our particulate grafting materials and membranes. Over-engineering of the socket to compensate for the 30-50% resorption is not optional!
Muska’s paper9 showed us that any pressure or expansion of the socket housing could fracture the buccal plate or enhance the speed of buccal plate resorption. Thus, forceps that luxate the roots buccal/lingually are not recommended. Similarly, rotational forces also create undue buccal plate expansion, since the root is never cylindrical in nature, as it is being elevated from the socket. Periotomes are instruments designed to sever the periodontal ligament fibers at the mesial and distal aspects of the socket, in order to facilitate and improve the efficiency of root elevators and vertical extractors, attempting to drag the root out of its socket with controlled forces. Expansion pressure on the buccal plate was the key ingredient promoting inflammatory resorption, but it was also found that rotational and vertical movements also incite an acute reaction because roots, of course, are again “not cylindrical”.10 Mother nature has designed human teeth with undercuts, dilacerated roots and many nuances which won’t allow traction easily. The other methodology of periotomes or specially designed forceps or a piezoelectric to control forces are just that…. forces that still expect the buccal plate to widen to experience traction in order to remove the root.
Finally, if none of those tools work, then we use our dental drill which can increase the surrounding osseous structures’ temperature up to 70°C and still leaves biofilm and smear layer and debris in the remaining socket, in addition to inadvertently removing 3-5mm of healthy surrounding bone structure. As far as minimally invasive devices go, the electrosurgical unit removes 1000-1500 cell layers at one swoop, the scalpel 100-300 cell layers, while the diode laser removes 15-25 cell layers. It is the erbium hard/soft tissue lasers that remove only 5-10 cell layers at a time. The Er,Cr:YSGG and the Er:YAG lasers both have this capability to be minimally invasive. But as laser machines are designed differently, dependent on the internal crystal and its subsequent wavelength of emitted light, the mode of delivery being either a fiber-optic trunk or an articulated arm, the Er,Cr:YSGG machine allows for more fluid and nimble movements in its handling, as opposed to the Er:YAG wavelength and machine design.
Laser MINIE extraction
As we integrate our scientific knowledge of socket resorption with the physics of erbium lasers, we can get a truly “artistic” and “minimally invasive approach” to a novel idea of how we extract teeth without even touching the buccal plate, leaving it intact to provide a four-walled defect for site development. In this way, ridge resorption following a MINIE extraction can be diminished when combined with socket grafts and collagen barriers.
There are four key points from current literature of the extraction socket healing process we can deem critical to the long-term survival of an implant, avoiding peri-implantitis:
a) A thin buccal bone wall in the esthetic zone defines the alveolar socket. Even a thin bony wall provides the framework for the outline of the buccal aspect of the alveolar process and, thus, the resorbable 4th wall in socket grafting.
b) The thin buccal plate will eventually resorb after a tooth extraction, following which, the soft tissue will collapse into the socket, creating a ridge defect. If an immediate implant was placed, the risk of facial dehiscence and a transparent tissue profile showing the grey implant would result.
c) An immediate implant placement does not prevent buccal bone loss, nor does a socket graft with various particulate bio-materials. Grafting the socket only limits the collapse of the soft tissues into the healing alveolar socket and supports bone formation. Thus, the preservation of the ridge dimension must occur as a compensatory mechanism for the buccal bone loss.
d) Finally, the tooth extraction, once considered a simple and straightforward surgical procedure, should be performed with laser precision and finesse and with the understanding that ridge reduction will follow and future hard/soft tissue grafting at the time of implant placement maybe necessary for esthetic and functional support of the implant and its long-term survival, but the amount of necessary secondary grafting is minimal and just supports the osteotomy site. In fact, Rasperini showed that less sinus lifting and augmentation was necessary with maxillary molars’ socket grafting.12
Matarasso13 and Walker14 both proved that with molar extraction sites, when socket preservation was done and the buccal bone was intact, less dimensional ridge alterations followed immediate implant placement in molar extraction sites at 6 months, while Walker et al showed evaluation of healing at molar extraction sites with and without ridge preservation with an intact buccal wall in a randomized controlled clinical trial, they showed 2.5X less grafting needed at the time of implant placement.
The role of an intact buccal plate cannot be emphasized enough, as this is the bone that money cannot buy. It is worth more than gold to the longevity of the future implant and the erbium laser is vital to the minimally invasive approach to tooth extraction in defining this long-term success of implants in our patients’ futures.
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About The Author
Dr. Preety Desai is the first Canadian periodontist implementing the all tissue laser into her specialty practice. After her periodontics board certification she has practiced in and called Kamloops BC her home. She has recently completed her specialty MSc Degree in Laser Dentistry from Germany and has implemented the erbium all tissue laser into all aspects of her surgical practice and now finds it indispensible for treatment of periimplantitis. In addition to full time practice, she is clinical associate professor at University of British Columbia, leading multiple study clubs. In addition, she has ALD Advanced Proficiency Status and is also a published author.