Petr Bartak - ASKLEPION Lasercentrum Prague, CZ

Roman Smucler - ASKLEPION Lasercentrum Prague, Dept. of Maxillofacial Surgery, 1st Medical School, Charles University Prague, CZ

E-mail: smucler@asklepion.cz

 

Abstract

The authors have verified the efficiency and safety of laser and high-frequency gingivectomy in non-periodontal indications. Within a prospective, non-selective study, they treated and monitored 357 dental areas in 139 teeth. Out of the total number, 248 areas were treated with a diode laser, 980 nm; 109 areas with high-frequency electrocauthery. The following parameters were monitored: (a) regeneration of the marginal gingiva; (b) generation of iatrogenic recessions or periodontal pockets; (c) bleeding from gingival sulcus during probing; (d) changes in tooth vitality; (e) patient`s subjective evaluation. The authors identified a high degree of safety in both laser and high-frequency gingivectomy, with no significant difference between these two methods. Laser gingivectomy appears to have a wider indication range, while high-frequency gingivectomy requires lower financial expenses.

 

Keywords: gingivectomy, diode laser, high-frequency electrocauthery

 

Introduction

When treating patients, dentists deal almost daily with the necessity of solving the problem of solid tooth tissue protruding apically in the margo gingivae. This may usually be necessary due to subgingival dental caries. In order to be sure that the dental caries can be effectively treated with the use of any material, it is necessary to ensure an environment without blood, saliva or other contaminations.

In addition, prosthetic preparation and impressions of the preparation margin require a dry and clear environment. The presence of liquid in the gingival sulcus disables the ideal application of impression medium, thus disabling correct reproduction of the prepared edge. Whenever we are forced to do subgingival preparation, it is rather difficult to ensure a dry environment.

There are several alternatives for the solution of this situation. In principle, it is necessary to find a manner in which to replace the gingival edge apically and turn a subgingival defect into a supragingival one.

As regards lesions which are only slightly below the gingival edge, it is sufficient to retract the gingiva mechanically.

Wherever retraction is impossible, there are three other alternatives: apically displaced flap, tooth extrusion (orthodontic or surgical) and gingivectomy. The first alternatives require repeated treatment which a number of patients refuse to accept and, in most cases, repeated treatment is useless. However these techniques are inevitable in case of insufficient biological area.

Gingivectomy performed with a scalpel will guarantee a blood-free wound only in an area without gingivitis. This is, however, very rare in connection with a subgingival defect. Chemical gingivectomy, e.g. with the use of trichloro-acetic acid, is not widely used in this country.

This is why gingivectomy performed with a high power laser or high-frequency electrocauthery has become the most convenient method for treating subgingival defects during a patient`s single visit. Laser excision offers much higher precision (in tens of micrometers). Compared to the laser method, electrocauthery is less costly. Both the methods ensure coagulation of the tissue on the surface of the cut, which will help to avoid bleeding and exudation from the cut area.

Despite a number of publications focussing on this topic, some basic questions remain unanswered. To what extent will free gingiva regenerate its height? How safe are these prosesses? Which of the two methods is more suitable? The objective of this paper is to provide answers to these questions.

 

Material

Laser device:

For the purpose of our study we used a diode laser - Ceralas 25 (Germany).

Technical specifications: wavelength - 980 nm, output measured at laser outlet - 25 W, output adjustable by 1 W, quasipulse length - 0.01 - 99 s, guide ray - diode laser 670 nm, transmission - standard silicon flexible fibre. The system is approximately the size of a desktop computer. It is portable, which means further reduction in the operating costs.

We use this device for gingivectomy in a continual mode, at an output 1 - 3 Watts, depending on the particular conditions. Soft tissues are prepared in contact with the light-conducting fibre, diameter of 0.75 or 1.0 mm. The contact with the gingiva must be as brief as possible and the fibre must be moving constantly. The laser beam is directed along the tooth macrodiagonally in order to minimise the risk of thermal damage caused to the rooth cement. If possible, we  protect the surface of a tooth with a suitable tool placed between the prepared tissue and the tooth.

Electrosurgical unit:

For the purpose of this study we used electrosurgical instrument SMT 50 MB Stom (Czech Republic).

Technical parameters: maximum output 75 W, monopolar mode, adjustable for cutting, mixed cutting, coagulation and micro-coagulation.

For our purposes we switched the instrument to mixed cutting, with the power output usually at 1/3, depending on the particular condition, in order to ensure smooth movement of the electrode in the operated tissue. During the operation, the patient holds a neutral electrode tightly in his/her palm. Needle and loop electrodes are the most frequently used ones. The contact between active electrode and soft tissues must be as brief as possible (approximately 1 second), with a time interval between individual contacts. We try to form the cut tissue into a conical shape. It is necessary to avoid contact between the electrode and metal restorations and elements in the patient`s mouth.

 

Methods

The study included all the patients visiting our office from 1st January, 2000, thru 31st October, 2002, with no further selections or limitations.

We carried out gingivectomy with the use of laser or high-frequency instruments, in operative and prosthetic dentistry indications, wherever it was impossible to use a less traumatising retraction and wherever the biological area was under no threat.

1.    Operative dentistry  

• Treatment of subgingival dental caries                                         
• Treatment of subgingival crown fracture
• Removal of ingrown gingiva from a carious defect
• Extension of a clinical crown to ensure filling resistance (e.g. in amalgam papilla completion)

2.    Prosthetic dentistry

• Placement of a preparation margin in healthy solid tissue for the treatment of subgingival caries or subgingival abutment implantation
• Subgingival crown fracture
• Necessity to modify previous subgingival preparations during the remodelling of prosthetics
• Extension of a clinical crown to ensure an adequate retention

 

We performed all the operations using local anesthesia. We used both the laser and the electrocauthery for the removal of gingiva in a scope so that it was possible to complete the operations successfully, without problems (caries excavation, cofferdam application, application and finishing of filling material, prosthetic preparation, celaning of preparation margin etc.).

After the operation, we removed coagulated tissue residues and left the wound free, without bandaging.

During follow-up checks of our patients, we evaluated healing of the marginal periodontium and vitality of undecayed teeth. We examined our patients using a WHO peroidontal probe, monitoring the following 5 factors:

1. Ability and possibility of the marginal gingiva to reach the apical edge of the new restoration after healing. We identified the areas in which the margo gingivae did not reach the apical edge of restoration as areas with soft tissue deficits. Other areas are areas without deficits.
2. Possible destructing effects and high-frequency gingivectomy on periodontal tissues, based on the development of recesses or periodontal pockets.
3. Bleeding from the gingival sulcus identified during the WHO probing in areas with completed gingivectomy.
4. We recognised signs of vitality in undecayed teeth with a cotton swab cooled with an agent used to check vitality (Cognoscin spray, Aveflor, Czech Republic), placed on the tooth neck.
5. Patient`s subjective evaluation of pain after the operation.

We examined our patients and recorded the results on an ongoing basis during each of their visits. For the requirements of this study, we divided the patients into two groups, based on the time elapsing between the date of the operation and the date of their last check-up:

1. Patients last examined 9 to 24 weeks after the operation
2. Patients last examined more than 24 weeks after the operation

We did this in order to allow the soft tissues time to heal (at least 8 weeks), and we also intended to monitor any possible negative effects of gingivectomy on the periodontium from a long-term perspective, as we believe that the necrosis of tissue caused by the thermal effect of high-frequency or laser energy would be clinically evident 6 weeks after the operation. Patients who failed to have a check-up after the gingivectomy and patients with a gingivectomy carried out less than 8 weeks ago were excluded from the study.

 

Results

From 1st January, 2000, to 31st October, 2002, we performed gingivectomy and evaluation of monitored parameters in 357 areas of 139 teeth. Out of the total number, 25 teeth were vital, others were decayed.

There were  248 areas operated upon with laser; 109 areas werre treated with high-frequency instrument. We have monitored 143 areas over the period of less than 24 weeks (6 months) and 214 areas over the period of of more than 24 weeks. A total of 11 (7.7%) areas checked in weeks 8 and 25 after the surgery showed a deficit of soft tissues (margo gingivae did not reach apical edge of restoration). There were 14 (6.5%) areas with a deficit of soft tissues evaluated 24 and further weeks after the operation. (See diagram 1).

 

 For the relation between soft tissue deficit, the instrument used, and time see Diagram 2.

 

Of all the areas operated upon, the total number of soft tissue deficits was 25 (7.0%) (See Diagram 3)

 

According to Diagram 4, the deficit of soft tissues appears in most cases (60%) in the oral areas of teeth.

 

Of all the cases evaluated as a deficit of soft tissues, none of the deficits exceeded 0.5 mm. This means that there were no clinically significant recesses.

In four areas we identified a false periodontal pocket deeper than 4 mm, 2 of the pockets bled during probing. We identified neither any genuine periodontal pockets nor any clinically evident depletion of periodontal soft tissues (cement, alveolar bone).

During examinations with a WHO probe 23 areas bled (See Diagram 3). This was particularly due to plaque in the tooth neck (16 areas). In some other cases, bleeding was caused by restoration edge that was too deep (3 areas), tartar (1 area), subgingival solid bond (1 area) and one papilla was oedematous due to extensive caries on the counter marginal area of an adjacent tooth. None of the bleeding areas showed a deficit of soft tissue.

All the teeth were vital before the gingivectomy, and showed signs of vitality at subsequent check-ups.

Subjective evaluation of pain after the operation varied to a considerable extent. On one hand, some patients complained of difficulties persisting for several days after the operation, on the other hand we find it surprising to see some patients after extensive gingivectomy of several teeth claiming that they have had no problems at all. 

In general, the operation was bearable for approximately 75 % of the patients, with no significant difference between the treatment with laser and high-frequency electrocauthery.

 

Discussion

Placing the edge of a filling or a prosthetic restoration in the subgingival area is a delicate problem. If possible, we should always try to avoid this situation. Unfortunately, this is not possible in many cases, particularly when treating a defect which is promarily localised under margo gingivae. It is, therefore, necessary to ensure a clear operation area for an ideal preparation of solid tooth tissue and for an optimum application and preparation of all parts within the restoration in question.

In most cases, subgingival intervention is necessary for subgingival dental caries. In particular, secondary caries within tha marginal areas of the teeth are usually located deep beneath interdental papilla. Gingiva or interdental papillaeirritated with sharp edges of bacteria of dental caries are usually oedematous, collapsing into a caries defect which makes further treatment quite complicated. They are also a source of annoying bleeding caused by preparation tools or mere drying air jet. In order to make sure that dental caries can be effectively treated with the use of any material, it is necessary to ensure an environment without blood, saliva or other contaminations.

Other possible reasons for subgingival intervention are subgingival crown fracture, gingiva ingrown in the defect, short clinical crown. necessity to treat former subgingival preparation.

Provided that the circumstances described above require the treatment of a deep defect, this treatment should be performed in order to avoid iatrogenic chronic irritation of marginal periodontium. It is necessary to create a clear operating field for an ideal preparation of solid tooth tissue and for application and finishing of all parts within the restoration in question.

In addition, it is necessary to respect biological range, i. e. the apical edge of restoration should not be closer than 2 mm to the alveolar crista. This distance should be maintained even with the use of osteotomy or extrusion.

Gingivectomy is an operation which cannot ensure the necessary biological range. It is, therefore, indicated for the treatment of medium-deep defects, sufficiently distant from the alveolar bone which cannot be treated after a mere retraction of gingiva. 

In practice, we prefer a non-bleeding laser cut or high-frequency electrocautery to a classic scalpel. The use of a scalpel cannot guarantee a bloodless operation and, in some cases, operations even have to be postponed. We are convinced that completion of an operation during a single visit of the patient is beneficial for the tooth, periodontium, patient and dentist. A precisely adapted and arranged restoration edge will ensure the best conditions for trouble-free healing of soft tissues and there is no reason to postpone final treatment. Only in aesthetically exposed areas do we postpone final prosthetic treatment by at least 8 weeks after gingivectomy, as there is a threat of a deficit in soft tissue (reported in 25 of 357 areas, of which vestibular areas were affected in 7 cases).

Evaluation of the gingivectomy area carried out in this study did not prove any development of gingival recesses or genuine periodontal pockets. However, we have identified four false periodontal pockets. The mechanism of their development is as follows: as the gingiva cannot join the material of the subgingival filling or prosthesis, sulcus gingivae remains near the tooth-restoration transition. In cases where the gingiva tends to grow over the apical restoration margin (i.e. reach its original course), a false periodontal pocket develops.

According to the outcome of the study, gingivectomy performed with a diode laser (wavelength 980 nm) is a safe alternative in the treatment of subgingival defects, based on the observation of the indication, principles concerning the safety of work with class IV lasers and with correctly adjusted parameters. The effects of laser emission are fully controllable. Thanks to its high absorption in water, the scope of the thermal effect in soft tissue around the impact point is limited to tens of micrometers. This means that there is no threat of undesirable propagation of heat in the surrounding area. Another benefit of this technology is the possibility to treat patients with haemorrhaging problems (thanks to ideal coagulation effect) or with an implanted electronic pacemaker which is an absolute contra-indication for electrosurgery.

High price is one of the disadvantages of the laser device. Moreover, manipulation with rather inflexible and fragile light-conducting fibre may be quite complicated in some locations.

Compared to laser technology, high-frequency electrosurgery is much less expensive; however, there are some disadvantages. It cannot be used for patients with an implanted electronic pacemaker. Particularly with an oedematous gingiva, it may be quite complicated to make a cut without bleeding and it is, therefore, necessary to consider application of this technology particularly with haemorrhaging problems.

Passage of electrical power though patient`s body during electrosurgical operations is subject to a number of factors and its propagation cannot be controlled. Under some circumstances, effects of electrosurgery may lead to the loss of a tooth. Unfortunately, we have had the opportunity to see this for ourselves. In 1999, we performed gingivectomy in an endodontically treated tooth, a 45, with an intrapulpal titanium pin and a plastic amalgam completion. During the operation, the active electrode came into brief contact with the amalgam on the distal tooth area. Sometimes it is almost impossible to avoid a brief contact with metal restoration of the treated tooth and, as a general rule, it has no negative impact on the course and outcome of the treatment. Unfortunately, this case resulted in anaemia of the tissue located mesially and distally from the treated tooth. On the second day the patient returned with extensive necrosis of the soft tissues, the tooth showed looseness of the 3rd grade and was painful to tapping. After 3 weeks, we removed a loosened bone sequester. We splinted the tooth with composite material, together with teeth 44 and 46.

133 days after the operation the tooth was extracted due to persistent pain. After extraction we identified a longitudinal fracture of the radix, through which electric power used for gingivectomy might have propagated into the periodontium causing such an extensive destruction. We cannot say whether the fracture occurred as a consequence of the contact between the active electrode and the metal part of the tooth and subsequent heating, or whether it was there before the gingivectomy and served as a route for the propagation of electric power into humid environment.

We have not concluded this isolated case of complication in our study, as the operation was performed before our study actually commenced. However, it is a proof of the fact that high-frequency surgery is not an absolutely safe method for periodontal tissue.

In our study, only 25 (18%) of total 139 teeth were vital, while the rest was decayed. This is also a proof of the fact that we opt for gingivectomy only for the treatment of seriously damaged teeth.

 

Conclusions

• Gingivectomy is an invasive operation which will always be reflected in the periodontal microstructure and which is limited to a certain extent. It should therefore be based on a corresponding indication.
• Our clinical study has proven that laser gingivectomy is a safe and effective method for presice treatment of subgingival defects.
• Under certain circumstances, high-frequency gingivectomy may lead to heavy destruction of the periodontium for the treated tooth. This may lead to extraction of the tooth, as described above.
• The use of high-frequency instruments is absolutely contraindicated in patients with an implanted electronic pacemaker. For patients with haemorrhaging problems it is necessary to proceed carefully, particularly with a gingivectomy in inflated tissue, as the coagulating property is less reliable. Laser is subject to no such restriction.
• Compared to an operation performed with a high-power laser, electrocauthery is several times cheaper.
• Regarding the monitored parameters, we have identified no difference between laser and high frequency gingivectomy.

 

Acknowledgements

The authors want to thank IGA MH, Czech republic, for financial support (IGA 5887-3)

 

References

1. H. Buhler, Extruze a apikální prodloužení nepříznivě frakturovaných zubů, Quintessenz, Praha, 2/1993, p. 55-61
2. J. H. Cleen, Ošetření na první pohled ztraceného zubu endodonticko-ortodontickým postupem, Quintessenz, Praha 3/1994, p. 28-30
3. A. Dapeci, Fixní zubní náhrady v prevenci parodontopatií, Masarykova universita Brno, 1990
4. G. S. Hethesray, Léčba invazívní cervikální resorpce - výsledky po lokální aplikaci kyseliny trichloroctové, kyretáži a rekonstrukci, Quintessenz, Praha 2/2002, p. 24-35
5. G. Kesler et al., Periodontal plastic surgery: thermal effect analysis using Er:YAG Kesler`s handpiece, Lasers in dentistry VI, San Jose 2000, p. 2-11
6. G. J. Mount, An Atlas of Glass-Ionomer Cements, Martin Dunitz Ltd., 1994
7. R. E. Mutschelknauss et al., Praktická parodontologie - klinické postupy, Nakl. Quintessenz, Praha 2002
8. P. Ngan, L. Knobloch, Pracovní postup k estetickému prodloužení klinické korunky přesahující rámec jednoho oboru, Quintessenz, Praha 6/1994, p. 63-66
9. A. Parashis, A. Tripodakis, Prodloužení korunky a rekonstrukční léčba poškozených molárů, Quintessenz, Praha 2/1996, p. 44-48
10. P. Rechmann, D. S.Goldi, Er:YAG lasers in dentistry: an overview, Lasers in dentistry IV, San Jose 1998, p. 2-13
11. J. Roeters, J. P. Bressers, Kombinace chirurgického ošetření a adhezivní rekonstrukce hluboké fraktury korunky, Quintessenz, Praha 5/2001, p. 7-11
12. H. T. Shilliburg jr., R. Jacobi, E. E. Brackett, Zásady preparace ve fixní protetice, Nakl. Quintessenz, Praha 1997
13. R. Šmucler, J. Mazánek, Er:YAG and Nd:YAG lasers in treatment of patients with contraindications of conventional dental and maxillofacial surgery, Lasers in dentistry VI, San Jose 2000, p. 42-49
14. J. Štraus, Vysokofrekvenční proud, Progresdent, Praha 6/2001, p. 32-35
15. T. Taieb, F. Galois, M. Danan, Preprotetické chirurgické prodloužení korunek, Quintessenz - Parodontologie, Praha 1/2000, p. 16-25
16. G. N. Wolffe, F. A. Weijden, A. J. Spanauf, G. Quincey, Umělé prodloužení korunky - řešení parodontálních, konzervačních a estetických problémů, Quintessenz, Praha 2/1995, p. 21-26