A new dimension in endo surgery: Micro endo surgery.

There is an immense difference between tradizional Endodontic Surgery and Micro-Endo Surgery. Microsurgical techniques made possible and accessible results,that were unimaginable before. Under microscopic control,the operative techniques reached continous changes,allowing a better precision and quality standards. The dramatic evolution from Endo Surgery to Micro-Endo Surgery has enlarged the horizon of therapeutic options. Illumination and magnification through the Microscope has fundamentally and radically changed the way endo surgery can be performed.

INTRODUCTION

Operatory Microscope has generally brought a new dimension in Dentistry and particularly in Endodontic Surgery [Figure 1a].

Figure 1

(a) Pecora, Rubinstein, Kim…the new dimension of teaching (b) Mirror and micromirrors (c and d) We can treat only what we can see

Light and magnification have determined a new higher standard of quality in the profession.[1]

Microscopy is a young specialty in a great and continuous evolution, not only in the field of application, but also in the development of new instruments and techniques.

Dentistry rests its quality standard on the realization of the higher possible precision.

Concepts based on evolution, advanced technology applications, characteristics of perfectioned materials have brought major improvment on long-term results and an excellent predictability in the surgical techniques.

In particular, the extensive use of the Microscope in conventional endo has enlarged the indications for the positive treatment of failures and restricted the indications for surgical treatment.

The concept of apical surgery has been expanded to periradicular surgery and today we speak in terms of Micro-Endo Surgery.[2]

Throughout the history of endodontics, never before there have been as many changes as in the last 25 years.

They have been dramatic, especially in Endodontic Surgery.

There is an immense difference between traditional Endodontic Surgery and Micro-Endo Surgery. A ‘New Dimension’ has been created working in different directions, which we can summarize in:

New operative protocol

Guided regeneration principles

Maxillary sinus management in Endo Surgery

Limits of conservative therapy

Implants as an alternative.

One of the most important advantages in using the Microscope is the evaluation of our surgical technique. More light can be shed on the rationality of the treatment to perform procedures in certain ways.

Microsurgery is defined as a surgical procedure on exceptionally small and complex structures with an operating microscope. This instrument enables the surgeon to assess pathological changes more precisely and to treat pathological lesions with the greatest precision, thus minimizing tissue damage during surgery.

Endodontic Microsurgery combines magnification and illumination, provided by the microscope, with the proper use of new microinstruments [Figure 1b].

It does not improve the access to the surgical field.

If the access is limited for traditional surgery, it will also be limited when the microscope is placed between the surgeon and the surgical field. However, the microscope creates a much better view of the surgical field by appropriate magnification and highly focused illumination.

Since vision is greatly enhanced, cases can be better treated with higher precision and accuracy. Microscopists often wonder how they managed to work without it in the past. There is a maxim: ‘to see better is to do better’. We might add: ‘to do it more easily’.[3]

The Microscope allows an exceptional evidentiation of the anatomy with the consequent possibility of a more accurate diagnosis and a more incisive operative capacity. Furthermore, the better vision leads to a less invasive approach respecting the tissues and, therefore, a lesser post-operative discomfort and faster healing.

The advanced technologies, applied to medical surgical specialties, have brought to exceptional progresses, achievement of unthinkable results and have also contributed to simplify technical steps, making them accessible to a larger number of specialists and more predictable in the results.

Dentistry has gone through many historical moments. Just think to the use of air drills and ultrasounds to the application of Magnetic Resonance and Laser.

Microsurgical techniques made possible and accessible results that were unimaginable before. Think to limbs reattachment, to otosclerosis surgery, to eye surgery, and you will understand that advanced technology and technical operative improvements today allow the opening of new frontiers.

In the 80's we had a raising interest for Microscope in Dentistry.

Sometimes, Endodontics has a limited visual field, with little and very little anatomic structures, and has particularly difficult vision of the inside of the tooth and the canals. Therefore, it has got major benefits from the possibility to see better through light and magnification.

Under microscopic control, the operative techniques reached continuous changes. The evolution towards suitable and practical modification, allows a better precision and quality standards.

‘We can treat only what we can see’.

The introduction of the Microscope in Endodontic Surgery will give clinicians the necessary means to treat difficult cases with a higher degree of confidence and clinical success.[4]

Once we reached the goal of an hermetic sealing of the Root Canal System (RCS) exits and, in particular, the sealing of the new apex, we expanded our horizon to Endo Perio Surgery.

We begun our treatments applying guided tissue regeneration (GTR) and guided Bone regeneration (GBR) principles to the borderline cases obtaining encouraging results. The use of the microscope allowed us to gain access to the maxillary sinus in a very conservative way. The diagnostic potential has grown as well as the therapeutic options and this allowed us to successfully intervene on the oro-antral pathologies.

On one hand, the microscope enhanced the orthograde treatment as well as the retreatment, reducing the indications for surgery; on the other hand, we started to deal with ‘impossible’ cases, moving the borderline towards conservative surgical treatment. In those cases in which the extraction of the tooth was the only alternative, we claimed for the endodontist the right to insert implants simoultaneously to the extraction with immediate loading.

The challenge for the future will be predictable for thesuccessfull management of the endo perio lesions.

New operative protocol

The step from apical surgery to periradicular micro surgery has involved new concepts, new techniques, new materials, new instruments but, particularly, the use of LIGHT and MAGNIFICATION through the surgical Microscope [Figures 1c and d].

All these phases of the surgical protocol have taken advantage from the use of this instrument and there have been tremendous changes in the approach and the execution of surgery.[5]

Many comparative clinical studies have been carried out to evidentiate the differences between traditional and micro surgery and the advantages in the use of the Microscope[6] [Figures 2a-f].

Figure 2

(a) Failure of endo-treatment (b) Apicoectomy without retrofilling (c) Recurrency at 3 years (d) Retrofilling 22X (e) Rx post-op control (f) Healing at 6 months

Rubinstein and Kim[78] have given scientific evidence that the increase of long-term success with Micro-Endo Surgery on molars premolars and single-rooted teeth has to be attributed to the utilization of the Microscope.

With its use, we can consider the following as the main advantages in our practice:

Easy identification of the apical third

Smaller osteotomies

Efficient evaluation of cut surface with minimal resection angle

Increased diagnostic power

Easier and safer management of anatomic structures

Mininvasive approach to pathological tissues

Potential of creating an hermetic seal in the neo-apex.[9]

The combination of microscope, ultrasonic tips and microintruments allows conservative, coaxial, deep root-end preparation and retrofilling. This satisfies the requirements for RCS sealing and the realization of the triad: cleaning, shaping, filling of the RCS itself.

When we begin a surgical treatment. the primary concern is to create conditions that favor healing of periradicular tissues either for regeneration or for repair.

These conditions include:

Removal of necrotic tissues

Removal of disintegration tissues

Decontamination of root surface

Entomb bacteria present in RCS

Removal of the apical part with the most accessory canals

Creation of the best neo-apical seal.

In the last decade, the operative protocol has undergone major evolution, achieving better results.

From the common experience of different operators and from literature investigation, we have stated technical determinant factors in the following steps:

Diagnosis

Flap design and elevation

Osteotomy[10]

Apicoectomy: Courettage

biopsy

emostasis

cut surface

Retrofilling[11]

GTR evaluation

Suture.

Hermetic seal of the neo-apex and exits of RCS is the target of surgical treatment [Figures 3a and b].

Figure 3

(a) Cutting surface evaluation, methylene blue 2% staining (b) Retro-filling control 22X

To perform the operative phases at best, we need:

A correct diagnosis and adequate treatment planning

The possibility to evaluate and choose the most favorable solution in case of controversial situations

A complete identification and visualization of the anatomy of the surgical area

The best quality level of each technical moment in the surgery

Correct evaluation of operatory risks

Minimal dissection and damage of healthy tissues.

Guided regeneration principles

The regeneration finds a limit in the dimension of the lesion. The concept of ‘critical size’ defect has its total application in Endodontic Micro-Surgery.

In some clinical situations, the total regeneration of the lost tissues is not possible due to pathological aggression.

There are many misunderstandings not only for the indication to guide the healing toward regeneration, but also among researchers on the techniques and the grafting materials.

A small defect undergoes spontaneous healing while a large defect has a different and non difficult healing. The ultimate goal of Micro-Endo Surgery is the predictability of the regeneration of the peri-apical tissues.[12]

It is important to define the difference between Regeneration and Repair.

Regeneration is a biological process to replace the destroyed tissues with new tissue that has same cells, same architecture, same function and capability of reaction against the pathologic stimulations.

Repair is a biologic process where the lost tissue is substituted by a new tissue with different cells, different architecture, different capability of reaction against the pathologic stimulations. This is an acceptable type of healing depending on which part of the root it occurs.

According to Pecora's anatomo-pathologic classification, we have: TYPE 1 (above the apex); TYPE 2 (middle root area); TYPE 3 (endo-perio communications) [Figures 4a-c].

Figure 4

(a) Lesion above the apex TYPE I (b) Middle root lesion TYPE II (c) Endo-marginal lesion

When a defect can spontaneously heal, bone fillers are ineffective or inappropriate.

However, there are many clinical situations requiring the use of regenerative materials and techniques:

Large lesions (more than 5 mm)[13]

T & T lesions[1415]

Endo-perio lesions[16]

Sinus membrane perforation[17]

Root perforations with large lesions.[18]

The prognostic limit of the regenerative techniques and therapeutic possibilities can be evaluated with Pecora's classification[19], where CLASS E lesions represent the ‘borderline’ and the evaluation criteria are based on the distance of bony walls and their thickness.

Large defects, endo-perio communications and through-and-through defects need a guide for healing. ‘Osteoconductive principle’ is based on this point.[20]

Osteoconduction occurs when a non-vital biomaterial works as a ‘scaffold’ in order to guide osteoblasts precursor cells into the defect.

The healing of the bone defect depends on the presence of these cells in the surrounding bone and tissue as well as on their capability to colonize the area and differentiate into osteoblasts.[21]

In borderline cases, a lesion of endodontic origin is complicated by the loss of the marginal attachment. The effectiveness of Endo-Surgery may be diminuished, if epithelial cells are allowed to populate the root surface. Membrane barriers inhibit this epithelial proliferation and, thereby, promote regeneration of funcional attachment.[22]

GTR techniques should be incorporated into the endodontic surgery protocols and used when indicated.

Today, the controversial use of regenerative therapies, even if limited in the indications and cases,- allows the clinicians to treat extreme cases and to have an optimal and predictable treatment of those lesions considered as ‘untreatable cases’ in the past [Figures 5a-d].

Figure 5

(a) Large lesion with endo-perio communication (b) Apicoectomy with calcium sulfate graft (c) Rx at 2 months (d) Rx at 6 months

Maxillary sinus management

Anatomical relations between apices of postero-superior teeth and maxillary sinus, imply the risk of endo-perio pathologies transmission, bacteria, debris, instruments’ penetration and resected apices violation during Endo-Micro Surgery.

All these potential clinical situations determine therapeutic needs, diagnostic and prognostic problems.

In the last years, the utilization of the Microscope has determined new horizons in the prevention and therapeutic options in Maxillary Sinus (MS) involvement during Endo-Surgery or consequent to endo-perio lesions.

The Endodontist has to be very careful when dealing with the following MS involvements:

Endo-perio

Cyst

EAS (endo antral syndrome)

OAC (oro antral communication)

OAF (oro antral fistula).

The Schneider's membrane of the sinus may present:

Thickening

Perforation.

With or without symptoms.

The MUST is to prevent foreign bodies, bacteria, debris penetration into the sinus, and if a perforationexists, the correct choice is its immediate closure.

If we have to perform an endo-surgery and if a thin layer of bone separates the apex from the sinus or if a communication pre or intra op occurs, the correct therapy is to close the perforation and increase the amount of bone above the neo-apex to prevent future recurrencies.

In case of perforation, a clean and precise operative technique is important to avoid the MS contamination. Particular attention has to be given to the type of healing and how the event may influence the healing process.

A study from Matisko et al., evidentiated that the use of GTR (collagene membranes) in MS perforation brings to bone formation when compared to spontaneous healing with fibrous tissue in the CONTROL sites, in rabbits.[17]

Limits of conservative therapy

Microsurgical procedures have implemented our skills to treat successfully most of the failures in the endo treatments. The application of GTR principles has moved many ‘heroic cases’ towards the conservative approach.[23]

Which is the limit between conservative treatment and overtreatment?

The feeble point is the success and failure evaluation criteria.

It is too simple to consider the lack of symptoms or clinical signs or a decreasing of the radiolucency a success. Many teeth, also if they cannot be included into the success criteria, remain asymptomatic and in-function for years.

The critical point is when the progression of infection is out of control and the situation may lead to massive bone loss, jeopardizing the future correct implant insertion.

Necessarily we have to respect a logic protocol, which foresees:

Endo-treatment

Eventual retreatment

Indication for surgery

Diagnostic flap

Possibility of infection control

Evaluation of healing and regenerative potential.

In the final decision, we have to consider, beyond periodontal and restorative considerations, factors as: esthetic, proprioceptive sensibility, postural balance, prosthetic relevance of the tooth, anatomic limitations, economical aspects and patient's will.

To the traditional goals of therapy:

Decreasing or disappearing of radiolucency

Control of symptoms

Restoring of function.

We have to add:

control of infection's progression and bone destruction.

Therapeutic option, correct diagnosis, predictability of the results have to be validated with a diagnostic flap. The microscope and the methylene blue as biological indicators, make it easier to chose between the different options.

Implants as alternative

Once the decision to extract the tooth is made, clinicians have to face two therapeutic options:

Immediate post-extraction regeneration

Fresh socket implant with immediate loading.

There are no objective criteria of evaluation, but only clinical experience and studies focusing single aspects of the problem exists.

The decision can be ‘the most favorable compromise’ when we combine experience of the operator, logical approach and a few fundamental points [Figures 6a and b].

Figure 6

(a) Untreatable horizontal fracture (tooth 2.1) (b) Fresh socket implant with immediate loading

Quality of bone and primary stability are the main factors. Primary stability depends on bone density and implant's design. Bone density depends on bone trabeculae and their structure.

It is essential for the surgeon to decide how and where to place the implant and whether an implant can be immediately loaded.

The leading concept is the evaluation of the post-extractive defect:

Presence of bony wall and thickness;

Endo-perio condition of the closer teeth;

Esthetic aspect (anterior or posterior teeth);

Acute infection or suppuration.

In a clinical study, Novaes and Novaes[24] concluded that the chronically infected sites do not constitute a contraindication for immediate implant placement if some pre-and post-operative clinical cares are followed:

Antimicrobical therapy pre- and post-op;

Meticolous cleansing and debridement of the alveoli before implant placement.

In presence of bone dehischence or missing bone wall, the choice is first to regenerate the bone and then place the implant, because the predictability of GTR techniques is questionable.

Immediate loading can be applied in some clinical situations where the control of micromotion is possible and if there are some important advantages:

Decreased healing time

Reduced resorption of alveolar bone

Achievement of optimal esthetic results.

In case of extraction sites in esthetic areas, there is a restorative challange and particular steps have to be followed in order to preserve site morphology and to support the existing hard and soft tissues:

Atraumatic tooth extraction with mininvasive operative techniques that minimize the treatment of the tissues;

Appropriate placement, orientation and stabilization of the implant.

Flapless surgery has been suggested as a favorable option to enhance implant esthetic, with several advantages:

Reduction of pain and swelling

Minimal intra operative bleeding

Reduction of surgical time

No need of suture

Maintenance of blood spply

Preservation of hard and soft tissues.

The only limitation is that this process requires more operative experience and pre surgical plannig for the inhability to visualize anatomic landmarks and vital structures.

A clinical study of Pecora et al. in 1996[25], pointed out that ‘the endodontist now has an additional choice of treatment in cases where tooth extraction is inevitable’.

In conclusion, the placement of implants immediately after extraction, seems to be a successful procedure.

Even if we have plenty of papers in literature that evidentiate the good results of the immediate implants, why they speak in terms of ‘implant survival’, remains an interrogative.

Survival is characterized by the maintainance of a certain function for a certain period of time without the respect of fixed parameters and without a long-term control.

Success is qualified and codificated in compliance with fixed parameters declared in the protocol and respected in the world's documented long-term results.

The optimal treatment plan incorporates the best available evidence together with specific case factors and the patient's desires and needs.[26] Dental implants provide a useful alternative to replace teeth that cannot otherwise be treated with a good prognosis.

It is impossible to give a proper evaluation to the success rate of the various treatments since the same criteria of evaluation of the results are inconsistent themselves.

Realistically, we cannot say that implants have a higher percentage of survival if compared with real teeth treated and reconstructed in a proper way.[27]

The availability of osteointegrated implants does not justify the extraction of natural teeth that can still offer a stable function.

A compromised tooth should be managed with a multidisciplinary approach and dental implants should be reserved for patients with truly end-stage tooth failure.

CONCLUSIONS

The dramatic evolution from Endo-Surgery to Micro-Endo Surgery has enlarged the horizon of therapeutic options.

Illumination and magnification through the Microscope have fundamentally and radically changed the way endodontic surgery can be performed.

The clinical experience has evidentiated the following benefits:

Optimal hermetic seal of the neo-apex

GTR application increases the long-term results in the treatment of borderline cases

Correct and favorable management of endo-sinus pathologies

Expanded diagnostic power in difficult clinical situations

Excellent evaluation of clinical data to accelerate the correct choice in the determination between TOOTH or IMPLANT.

‘SEE BETTER…DO BETTER’.

Finally, we would like to stress the concept that fresh socket implants with endodontic indications have to be considered an important part of the Endodontists’ daily practice.

The diagnostic flap helped us to clarify that the post-extractive therapeutic options have to follow the decision to extract the tooth since the immediate loading has become a trustable and predictable solution.