Braz Dent J (1998) 9(2): 105-108 ISSN 0103-6440
| Introduction | Material and Methods | Results | Discussion | Conclusions | References |
The effectiveness of three methods of lingual dentin edge removal was evaluated in maxillary canines: Batt burs (group I), Gates-Glidden burs (group II) and manual reamers, Batt burs and Gates-Glidden burs (group III). The results showed better dentin edge removal and degree of conicity in group III.
Key Words: root canal therapy, dental pulp cavity.
The access and preparation of the pulp chamber are important factors during endodontic therapy. According to Korzen and Pulver (1990), this phase must include: 1) visualization: easier to locate the orifice entrance of the root canal; 2) straight line access: provides a straight access to the apical portion of the root canal; 3) the removal of all "debris" from the pulp chamber: it is important that all remaining tissues be removed from the pulp chamber before instrumentation in order to prevent bacterial recontamination and the consequent darkening of the tooth crown; 4) condition for temporary sealing: the access of the pulp chamber must have a shape that allows the intra-canal medication to remain between visits, without displacement or infiltration.
According Janik (1984), for many dentists the preparation of the pulp chamber represents nothing more than an opening made in a tooth through which the pulp can be reached. Because of this, several teeth may be lost. Weine (1982) reported that all endodontic treatment is based on the correct and precise preparation of the pulp chamber. Ingle (1974) believes that as in dentistry, the final restoration is rarely better than the initial cavity preparation. According to De Fazio et al. (1990), access to the pulp chamber should seek three targets: 1) the access to the floor of the pulp chamber and its walls, 2) removal of all pulp chamber roof, and 3) visibility of the orifice entrance of the root canals.
Thus, the access to the pulp chamber should allow a perfect access of instruments to all walls of the root canal. It is very important that during this phase all of the pulp chamber roof be entirely removed.
In relation to the anterior teeth it is important that besides this measure, the lingual dentin edge located at the entrance of the root canal should be removed.
The aim of this study is to evaluate three different methods for the removal of this dentin edge.
Material and Methods
A total of 54 maxillary canines were used after being extracted due to many reasons and kept with no special care. Initially, the teeth were kept in numbered bottles with physiologic saline for 72 hours for hydration. The teeth were then removed from the bottle, and access to the pulp chamber was made. Initially with a diamond conic shaped bur, a sulcus was made on the lingual surface of the tooth approximately 1.0 mm from the cingulum.
Using a diamond spherical shaped bur, we made a triangular section cavity from this sulcus in the incisal direction, and as this cavity was enlarged, we deepened the bur in the direction of the pulp chamber until the dentin was reached. Of course, the bur reached to the tooth apex.
Once the dentin was reached we proceeded using a round carbide bur until the vicinity of the pulp chamber, and we made the trephination of the pulp chamber with this bur and removed the pulp chamber roof.
The teeth were divided into three groups, each one representing a different method of lingual dentin edge removal: Group I: Batt burs (Maillefer, Switzerland ) ISO 012, 014 and 016; Group II: Gattes-Glidden burs (Maillefer) # 1, 2 and 3; Group III: manual reamers (Maillefer) # 1, 2 and 3, Batt burs (Maillefer) ISO 012, 014, and Gattes-Glidden burs (Maillefer) # 1 and 2.
After this procedure, the tooth was returned to its original bottle. An impression of the cavities was made with a silicon-based material with a vacuum aspirator after at least 7 days.
Before the impressions, the teeth were externally dried with filter paper, and the canals with a metallic aspiration tip connected to a vacuum bomb and paper points. After the impressions, the teeth were submitted to decalcification with 35% chloride acid for 48 hours. The remaining dental tissue was then removed with a shaving blade leading to the access cavity.
The specimens were examined with a 20X lens in order to see the degree of removal of the dentin edge and the conicity of the preparation.
The results can be found in Tables 1 and 2.
The removal of the dentin edge was partial in four specimens of groups I and II and in 2 teeth of group III.
There was total conicity of the preparation in 10 teeth from both groups I and II and in all specimens examined from group III.
Statistical analysis with the Fisher test revealed a significance of 1% for group III in terms of conicity.
Endodontic therapy aims at maintaining the tooth in its total function within the dental arcade. Thus, endodontics varies from diagnosis to control.
According to a technical point of view, endodontic treatment includes the adequate access and preparation of the pulp chamber, both being fundamental for the appropriate emptying, preparation and filling of root canals.
It is very important to remember that the access surgery differs from tooth to tooth and as reported by De Fazio et al. (1990), access should involve the floor and walls of the pulp chamber, the removal of the roof and the perfect visibility of the canal entrance. Instrumentation of the root canal would be more uniform if the dentin edge was removed.
This study analyzed 3 techniques with the aid of silicone impressions. The Batt and Gates-Glidden burs showed the same performance for both the dentin edge removal and the conicity of the root canal. On the other hand, when these instruments were associated with manual reamers the results were more satisfactory.
We believe that the use of the Batt bur should be complemented with the Gates-Glidden bur. The use of reamers promotes an enlargement of the canal which provides a better adaptation of the rotary instruments.
1. Group III proved to be more effective in the total removal of the dentin edge.
2. The comparison of Groups I and II in the removal of the dentin edge and the conicity of the preparation showed no difference.
3. Group III showed more frequent conic preparation in relation to Groups I and II.
De Fazio P, Petrecca S, Esposito P, Petrelle T: Metodiche di apertura della camera pulpare. G di Endo 4: 6-10 1990
Ingle JI: Endodontics. Lea and Febiger, Philadelphia 1974
Janik JM: Access cavity preparation. Dent Clin N Am 28: 809-818, 1984
Korzen BH, Pulver WH: Endodontic access cavities - The first step to success. Ontario Dentist 55: 19-22, 1978
Weine FS: Endodontic therapy. 3rd ed. CV Mosby Co., St. Louis 1982
Correspondence: Admilson Carrascoza, Av. Salgado Filho 38, Centro, 07115-000 Guarulhos, SP, Brasil.
Accepted June 5, 1998
Electronic publication: April, 1999