Abstracts
Introduction
Accurate dimensions of cast-metal posts are relevant to the survival of dental prostheses.
Objective
The aim of this study was to verify if the dimensions of cast-metal posts accord with ideal clinical criteria.
Material and method
For the evaluation, 285 periapical radiographs, from a total of 80 teeth, were taken from the charts of patients that attended the clinics at the Dental School of the Federal University of Goiás, from March 2008 to October 2012. Only periapical radiographs of single-rooted teeth with post and core were included in the study. The radiographic evaluation was conducted with the assistance of a magnifying glass and a view box, in a room with low luminosity. The dimensions of the post and core were established with the help of a digital caliper, and the following measurements were considered: a) LR (Length Remnant); b) LP (Length Post); c) BS (Bone Support); d) DR (Diameter Root); e) DP (mesiodistal diameter post). The post and core were classified as acceptable or deficient by reference values with a margin of error of 0.2 mm. For descriptive analysis, the data were cataloged using SPSS software (version 17.0).
Result
With regard to the length of the post and core, only 26.25% and 43.75% of the post and core were classified as acceptable according to the two-thirds rule and fulcrum dental rule, respectively. With regard to the mesiodistal diameter of the post and core, 55% were classified as acceptable.
Conclusion
Within the limits of this study, it can be concluded that the cast-metal posts evaluated do not accord with the ideal clinical criteria.
Post and core technique; quality control; partial fixed denture
Introdução
As dimensões corretas de um retentor intrarradicular são bastante relevantes para a longevidade de uma prótese.
Objetivo
O objetivo deste estudo foi comprovar se as dimensões de retentores metálicos fundidos estão de acordo com critérios clínicos ideais.
Material e método
Foram analisadas 285 radiografias periapicais de diagnóstico, totalizando 80 dentes, de pacientes que procuraram atendimento na Faculdade de Odontologia/UFG, no período de março de 2008 a outubro de 2012. Foram incluídas no estudo as radiografias periapicais de dentes unirradiculares, que apresentavam retentor intrarradicular metálico fundido. A avaliação radiográfica foi realizada em ambiente com pouca luminosidade e com auxílio de um negatoscópio com lupa. A dimensão dos retentores foi estabelecida através de um paquímetro digital considerando as seguintes medidas: a) comprimento do remanescente (CR); b) comprimento do retentor intrarradicular (CRI); c) suporte ósseo (SO), diâmetro mésio-distal da raiz (DR); d) diâmetro mésio-distal do retentor intrarradicular (DRI). Por meio de parâmetros de referência os retentores foram classificados em aceitáveis, com margem de erro de até 0,2 mm, ou deficientes. Para a análise descritiva os dados foram catalogados utilizando-se o software SPSS 17.0.
Resultado
Quanto ao comprimento, pela análise da regra dos 2/3 apenas 23,75% dos retentores foram classificados como aceitáveis, enquanto na regra do fulcro dentário essa porcentagem foi de 37,5%. Com relação ao diâmetro mésio-distal 52,5% dos retentores foram aceitáveis.
Conclusão
Dentro dos limites deste estudo, pode-se concluir que os retentores metálicos fundidos avaliados não estão de acordo com os critérios clínicos ideais.
Técnica para retentor intrarradicular; controle de qualidade; prótese parcial fixa
INTRODUCTION
Endodontically treated teeth usually exhibit pronounced coronal destruction11 Raiden GC, Gendelman H. Effect of dowel space preparation on the apical
seal of root canal fillings. Endod Dent Traumatol. 1994 June;10(3):109-12.
http://dx.doi.org/10.1111/j.1600-9657.1994.tb00534.x. PMid:7995238
http://dx.doi.org/10.1111/j.1600-9657.19...
as a result of caries or endodontic
treatment22 Pilo R, Cardash HS, Levin E, Assif D. Effect of core stiffness on the in
vitro fracture of crowned, endodontically treated teeth. J Prosthet Dent. 2002
Sept;88(3):302-6. http://dx.doi.org/10.1067/mpr.2002.127909.
PMid:12426501
http://dx.doi.org/10.1067/mpr.2002.12790...
. When teeth are
severally damaged, posts are indicated to retain stability for the final
restoration11 Raiden GC, Gendelman H. Effect of dowel space preparation on the apical
seal of root canal fillings. Endod Dent Traumatol. 1994 June;10(3):109-12.
http://dx.doi.org/10.1111/j.1600-9657.1994.tb00534.x. PMid:7995238
http://dx.doi.org/10.1111/j.1600-9657.19...
. Additionally,
factors such as quality of bone support and type of forces to which teeth will be
submitted must be considered in the selection of restorative procedure33 Teófilo LT, Zavanelli RA, de Queiroz KV. Retentores intra-radiculares:
revisão de literatura. PCL Rev Ibero-Am Prót Clín Laboratorial. 2005
Apr-June;7(36):183-93..
The posts are classified as conventional metallic and pre-fabricated44 Goracci C, Ferrari M. Current perspectives on post systems: a literature
review. Aust Dent J. 2011 June;56(1 Suppl):77-83.
http://dx.doi.org/10.1111/j.1834-7819.2010.01298.x. PMid:21564118
http://dx.doi.org/10.1111/j.1834-7819.20...
, and are indicated in situations with
wide coronal destruction, when the remaining tooth is unable to retain the core. Four
factors must be analyzed to promote a suitable retention to the post: length, wall
inclination, width and surface characteristics55 Klautau EB, Souza PS, Barros CMTM, Garcia V, Maranhão KM. Radiographic
evaluation of endodontic treatment and radicular retainer quality. Salusvita. 2009;
28(1):21-9.. The appropriate length of the post is synonymous with
prostheses longevity; therefore, inadequate length will contribute to stress
concentration in some areas, which can lead to radicular fractures55 Klautau EB, Souza PS, Barros CMTM, Garcia V, Maranhão KM. Radiographic
evaluation of endodontic treatment and radicular retainer quality. Salusvita. 2009;
28(1):21-9.. Such fractures are more frequent when the
intraradicular portion of the post is shorter than the crown length. These circumstances
occur at a stress concentration in the apical portion of the post; the site of root
fracture.
According to the literature, some criteria are to be adopted together or individually to
determine the ideal length of the post. In this case, the ideal post is considered to
have a length equal to two-thirds the total length of the remnant dental structure
(two-thirds rule), half the length of the root66 Zmener O. Effect of dowel preparation on the apical seal of
endodontically treated teeth. J Endod. 1980 Aug;6(8):687-90.
http://dx.doi.org/10.1016/S0099-2399(80)80132-4. PMid:7005379
http://dx.doi.org/10.1016/S0099-2399(80)...
, a length equal to or greater than the crown of the future
restoration11 Raiden GC, Gendelman H. Effect of dowel space preparation on the apical
seal of root canal fillings. Endod Dent Traumatol. 1994 June;10(3):109-12.
http://dx.doi.org/10.1111/j.1600-9657.1994.tb00534.x. PMid:7995238
http://dx.doi.org/10.1111/j.1600-9657.19...
and half the bone
support surrounding the root (dental fulcrum rule)66 Zmener O. Effect of dowel preparation on the apical seal of
endodontically treated teeth. J Endod. 1980 Aug;6(8):687-90.
http://dx.doi.org/10.1016/S0099-2399(80)80132-4. PMid:7005379
http://dx.doi.org/10.1016/S0099-2399(80)...
.
Selby77 Selby A. Fixed prosthodontic failure. A review and discussion of
important aspects. Aust Dent J. 1994 June;39(3):150-6.
http://dx.doi.org/10.1111/j.1834-7819.1994.tb03083.x. PMid:8067930
http://dx.doi.org/10.1111/j.1834-7819.19...
systematically reviewed the
likely failure of fixed prostheses and found that short and narrow posts, as well as
conventional metallic posts, were the main factors leading to the failure of many
endodontically treated teeth.
Although the techniques for obtaining the posts are very well defined and of great
importance for the success of rehabilitative treatment, there are studies showing that
even nowadays, the step of determining the dimensions (length and diameter) of metallic
post retainers is often neglected88 Hilgert E, Buso L, Mello EB, Valera MC, Araújo MAM. Avaliação
radiográfica de retentores intra-radiculares metálicos fundidos. Ciênc Odontol Bras.
2004; 7(4):52-9..
This may explain the high rates of failure in teeth with this kind of treatment99 Sorensen JA, Martinoff JT. Intracoronal reinforcement and coronal
coverage: a study of endodontically treated teeth. J Prosthet Dent. 1984
June;51(6):780-4. http://dx.doi.org/10.1016/0022-3913(84)90376-7.
PMid:6376780
http://dx.doi.org/10.1016/0022-3913(84)9...
.
Given the importance of the topic in the context of oral rehabilitation, the aim of this study was to prove the null hypothesis that the dimensions of metallic posts of patients seeking dental care at the Dental School of the Federal University of Goiás (UFG) accord with ideal clinical criteria.
MATERIAL AND METHOD
A total of 285 periapical radiographs, totaling 80 teeth, were analyzed. The radiographs were obtained from the medical records of patients seen in the disciplines of integrated clinical internship at the Dental School of UFG, from March 2008 to October 2012. There was not any damage on radiographs and patient identity was not revealed. Prior to data collection, the project was approved by the Ethics Committee in Research of UFG (protocol 147/12).
As inclusion criteria, only periapical radiographs of single-rooted teeth with metallic posts were selected. Unclear radiographs of poor quality and those with distortion and an average degree of density and contrast were excluded.
Radiographic analysis was performed by two calibrated observers, in an environment with low light and a light box (model: Endo Bench) with magnifier (Protécni, Araraquara, Brazil). The dimensions (in mm) of the metallic posts were established with the aid of a digital caliper (Mitutoyo Model 500-144B, Mitutoyo Sul Americana, São Paulo, Brazil) taking into consideration the parameters illustrated in Figure 1.
The parameters were: LR (Length Remnant), LP (Length Post), BS (Bone Support), DR (Diameter Root), and DP (mesiodistal diameter post). Measurements for the diameter were performed in the middle third of the root.
Given the impossibility of determining the buccolingual diameter radiographically, the data regarding the diameter of posts in the present study are limited to the mesiodistal direction.
Radiographs were identified by ascending order of numbers. The average of three measurements (in mm) was obtained for each of the five parameters. The obtained values were applied to the formulations described in Table 1.
For the length of the two benchmarks, the two-thirds rule and the dental fulcrum were analyzed separately and together.
According to the adopted reference parameters, the posts were classified as acceptable or deficient. Measurements with a margin of error of up to 0.2 mm were considered acceptable. The cataloged data were evaluated by descriptive analysis using SPSS 17.0 software (SPSS Inc., Chicago, IL, USA).
RESULT
The results of the analysis of the 80 teeth with respect to the length, two-thirds rule and dental fulcrum rule, and the ideal diameter of the post are shown in Table 2.
Only 26.25% of the posts were classified as acceptable according to the two-thirds rule, and only 43.75% according to the dental fulcrum rule. Considering the two references of length together, the results were identical to those obtained with the two-thirds rule, with 26.25% of the posts considered acceptable. However, with respect to the diameter, there was a lower number of disabled posts, with 55% classified as acceptable.
DISCUSSION
With the increasing advancement of dental materials and with the advent of adhesive
systems, many changes are occurring in the dental specialties22 Pilo R, Cardash HS, Levin E, Assif D. Effect of core stiffness on the in
vitro fracture of crowned, endodontically treated teeth. J Prosthet Dent. 2002
Sept;88(3):302-6. http://dx.doi.org/10.1067/mpr.2002.127909.
PMid:12426501
http://dx.doi.org/10.1067/mpr.2002.12790...
in reference to rehabilitation procedures. In this
context, a growing number of studies suggest the use of fiberglass posts instead of the
conventional metallic posts1010 Sarkis-Onofre R, Jacinto RC, Boscato N, Cenci MS, Pereira-Cenci T. Cast
metal vs. glass fibre posts: a randomized controlled trial with up to 3 years of
follow up. J Dent. 2014 May;42(5):582-7.
http://dx.doi.org/10.1016/j.jdent.2014.02.003. PMid:24530920
http://dx.doi.org/10.1016/j.jdent.2014.0...
.
However, conventional metallic posts are still needed. Notably, there is a higher
prevalence of this type of rehabilitative treatment, especially in undergraduate courses
in dentistry, due to its low cost when compared with the use of fiberglass posts1111 Heling I, Gorfil C, Slutzky H, Kopolovic K, Zalkind M, Slutzky-Goldberg
I. Endodontic failure caused by inadequate restorative procedures: review and
treatment recommendations. J Prosthet Dent. 2002 June;87(6):674-8.
http://dx.doi.org/10.1067/mpr.2002.124453. PMid:12131891
http://dx.doi.org/10.1067/mpr.2002.12445...
.
In the present study, most of the retainers (73.75%) were classified as deficient, taking into account the two-thirds rule. When considering the dental fulcrum rule, 56.25% of the retainers were considered deficient.
This type of deficiency concentrates the forces that will act away from the dental
fulcrum, and can contribute to the fracture of the dental
fulcrum, since the mechanical behavior between the prosthetic
crown and post is the cross-resistance of a lever, wherein
occlusion represents the strength of action, the apical portion of the root represents
the fulcrum, and the strength of resistance is given by intraradicular1212 Zarone F, Sorrentino R, Apicella D, Valentino B, Ferrari M, Aversa R, et
al. Evaluation of the biomechanical behavior of maxillary central incisors restored
by means of endocrowns compared to a natural tooth: a 3D static linear finite
elements analysis. Dent Mater. 2006 Nov;22(11):1035-44.
http://dx.doi.org/10.1016/j.dental.2005.11.034. PMid:16406084
http://dx.doi.org/10.1016/j.dental.2005....
.
Pinzetta et al.1313 Pinzetta AL, Inoue RT, Feltrin PP. Avaliação radiográfica da proporção
comprimento de pinos intra-radiculares em relação ao comprimento radicular em dentes
suporte de próteses fixas unitárias e compostas. RGO – Rev Gaúcha Odontol. 2006
Out-Dez; 54(4):302-7. evaluated 96 teeth
and found that 96.9% had posts with a length less than two-thirds of the remaining
dental structure. Although inadequate length is one of the main reasons for failure in
teeth with this kind of rehabilitative treatment1414 Pinto LR, Bonfante G, Lopes JFS. Evaluation of cast metallic posts
reproduction according to its quantity and position inside the casting ring. J Appl
Oral Sci. 2005 Mar;13(1):62-6. http://dx.doi.org/10.1590/S1678-77572005000100013.
PMid:20944883
http://dx.doi.org/10.1590/S1678-77572005...
, a direct relationship of this factor with the longevity of
the prosthesis cannot be established. Other important factors must be included in this
analysis, such as antagonist quality and sex of the patient, which are important
determinants of incident power for the prosthesis.
The effects of a short post include displacement by inadequate retention and root
fracture introduced into the lower lever. Even with several in vitro and clinical
studies indicating that the length of posts significantly affects retention and several
other properties1515 Stockton LW. Factors affecting retention of post systems: a literature
review. J Prosthet Dent. 1999 Apr;81(4):380-5.
http://dx.doi.org/10.1016/S0022-3913(99)80002-X. PMid:10095205
http://dx.doi.org/10.1016/S0022-3913(99)...
, Morgano et
al.1616 Morgano SM, Milot P. Clinical success of cast metal posts and cores. J
Prosthet Dent. 1993 July;70(1):11-6. http://dx.doi.org/10.1016/0022-3913(93)90030-R.
PMid:8366452
http://dx.doi.org/10.1016/0022-3913(93)9...
found that most of the
analyzed posts that failed were less than half the length recommended by the literature.
This shows the important influence of the length of posts in the success of this type of
rehabilitative treatment.
With respect to radiographic diameter, 45% of cases (Table 2) presented below what is advocated in the literature. However, it is
known that increasing the diameter of posts increases the retention and strength, but
there is also an increased risk of fracture due to increased intraradicular wear on the
remaining dentin. In vitro studies have confirmed the importance of maintaining healthy
dental structure (intraradicular dentin) surrounding the post to prevent root
fracture1717 Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay FR, Breschi L, et al. A
randomized controlled trial of endodontically treated and restored premolars. J Dent
Res. 2012 July;91(7 Suppl):72S-78S. http://dx.doi.org/10.1177/0022034512447949.
PMid:22699672
http://dx.doi.org/10.1177/00220345124479...
,1818 Fokkinga WA, Kreulen CM, Bronkhorst EM, Creugers NH. Up to 17-year
controlled clinical study on post-and-cores and covering crowns. J Dent. 2007
Oct;35(10):778-86. http://dx.doi.org/10.1016/j.jdent.2007.07.006.
PMid:17716800
http://dx.doi.org/10.1016/j.jdent.2007.0...
. Increasing the diameter of the post
does not guarantee a significant increase in retention of the post1919 Hunter AJ, Feiglin B, Williams JF. Effects of post placement on
endodontically treated teeth. J Prosthet Dent. 1989 Aug;62(2):166-72.
http://dx.doi.org/10.1016/0022-3913(89)90306-5. PMid:2668511
http://dx.doi.org/10.1016/0022-3913(89)9...
; however, it may increase the stiffness of the post
and reduce the resistance to root fracture2020 Trope M, Maltz DO, Tronstad L. Resistance to fracture of restored
endodontically treated teeth. Endod Dent Traumatol. 1985 June;1(3):108-11.
http://dx.doi.org/10.1111/j.1600-9657.1985.tb00571.x. PMid:3893998
http://dx.doi.org/10.1111/j.1600-9657.19...
. Therefore, the diameter of posts must be controlled to not
only preserve intraradicular dentin, but also resist root fractures.
Due to limitations in the information provided by periapical radiographs in this study, it was only possible to determine the mesiodistal diameter of the posts evaluated. This should be considered when interpreting the data.
Given the direct relationship between the dimensions of posts and the longevity of the tooth root, it is necessary to adopt well-defined criteria for predictability in treatments with these restraints.
A tooth that has received a post with the length following the two-thirds rule, but in which the sealing of the apical third root has been compromised and is subsequently attacked by a periapical lesion, is considered a failure. In this situation, even with a suitable mechanical post, there will be a need for corrective interventions, either by removing the post via endodontic retreatment or by surgery for sanitization of the periapical region.
Given the results of this study, the proposed hypothesis was rejected, revealing a clear need for change in clinical management with respect to the determination of the dimensions of posts. More than half of the teeth examined presented with posts with a length that did not follow the dental fulcrum rule. Knowing this can help professionals provide prosthetic treatments with greater clinical longevity.
CONCLUSION
Within the limits of this study, it can be concluded that the conventional metallic posts evaluated do not accord with the ideal clinical criteria.
REFERENCES
-
1Raiden GC, Gendelman H. Effect of dowel space preparation on the apical seal of root canal fillings. Endod Dent Traumatol. 1994 June;10(3):109-12. http://dx.doi.org/10.1111/j.1600-9657.1994.tb00534.x. PMid:7995238
» http://dx.doi.org/10.1111/j.1600-9657.1994.tb00534.x -
2Pilo R, Cardash HS, Levin E, Assif D. Effect of core stiffness on the in vitro fracture of crowned, endodontically treated teeth. J Prosthet Dent. 2002 Sept;88(3):302-6. http://dx.doi.org/10.1067/mpr.2002.127909. PMid:12426501
» http://dx.doi.org/10.1067/mpr.2002.127909 -
3Teófilo LT, Zavanelli RA, de Queiroz KV. Retentores intra-radiculares: revisão de literatura. PCL Rev Ibero-Am Prót Clín Laboratorial. 2005 Apr-June;7(36):183-93.
-
4Goracci C, Ferrari M. Current perspectives on post systems: a literature review. Aust Dent J. 2011 June;56(1 Suppl):77-83. http://dx.doi.org/10.1111/j.1834-7819.2010.01298.x. PMid:21564118
» http://dx.doi.org/10.1111/j.1834-7819.2010.01298.x -
5Klautau EB, Souza PS, Barros CMTM, Garcia V, Maranhão KM. Radiographic evaluation of endodontic treatment and radicular retainer quality. Salusvita. 2009; 28(1):21-9.
-
6Zmener O. Effect of dowel preparation on the apical seal of endodontically treated teeth. J Endod. 1980 Aug;6(8):687-90. http://dx.doi.org/10.1016/S0099-2399(80)80132-4. PMid:7005379
» http://dx.doi.org/10.1016/S0099-2399(80)80132-4 -
7Selby A. Fixed prosthodontic failure. A review and discussion of important aspects. Aust Dent J. 1994 June;39(3):150-6. http://dx.doi.org/10.1111/j.1834-7819.1994.tb03083.x. PMid:8067930
» http://dx.doi.org/10.1111/j.1834-7819.1994.tb03083.x -
8Hilgert E, Buso L, Mello EB, Valera MC, Araújo MAM. Avaliação radiográfica de retentores intra-radiculares metálicos fundidos. Ciênc Odontol Bras. 2004; 7(4):52-9.
-
9Sorensen JA, Martinoff JT. Intracoronal reinforcement and coronal coverage: a study of endodontically treated teeth. J Prosthet Dent. 1984 June;51(6):780-4. http://dx.doi.org/10.1016/0022-3913(84)90376-7. PMid:6376780
» http://dx.doi.org/10.1016/0022-3913(84)90376-7 -
10Sarkis-Onofre R, Jacinto RC, Boscato N, Cenci MS, Pereira-Cenci T. Cast metal vs. glass fibre posts: a randomized controlled trial with up to 3 years of follow up. J Dent. 2014 May;42(5):582-7. http://dx.doi.org/10.1016/j.jdent.2014.02.003. PMid:24530920
» http://dx.doi.org/10.1016/j.jdent.2014.02.003 -
11Heling I, Gorfil C, Slutzky H, Kopolovic K, Zalkind M, Slutzky-Goldberg I. Endodontic failure caused by inadequate restorative procedures: review and treatment recommendations. J Prosthet Dent. 2002 June;87(6):674-8. http://dx.doi.org/10.1067/mpr.2002.124453. PMid:12131891
» http://dx.doi.org/10.1067/mpr.2002.124453 -
12Zarone F, Sorrentino R, Apicella D, Valentino B, Ferrari M, Aversa R, et al. Evaluation of the biomechanical behavior of maxillary central incisors restored by means of endocrowns compared to a natural tooth: a 3D static linear finite elements analysis. Dent Mater. 2006 Nov;22(11):1035-44. http://dx.doi.org/10.1016/j.dental.2005.11.034. PMid:16406084
» http://dx.doi.org/10.1016/j.dental.2005.11.034 -
13Pinzetta AL, Inoue RT, Feltrin PP. Avaliação radiográfica da proporção comprimento de pinos intra-radiculares em relação ao comprimento radicular em dentes suporte de próteses fixas unitárias e compostas. RGO – Rev Gaúcha Odontol. 2006 Out-Dez; 54(4):302-7.
-
14Pinto LR, Bonfante G, Lopes JFS. Evaluation of cast metallic posts reproduction according to its quantity and position inside the casting ring. J Appl Oral Sci. 2005 Mar;13(1):62-6. http://dx.doi.org/10.1590/S1678-77572005000100013. PMid:20944883
» http://dx.doi.org/10.1590/S1678-77572005000100013 -
15Stockton LW. Factors affecting retention of post systems: a literature review. J Prosthet Dent. 1999 Apr;81(4):380-5. http://dx.doi.org/10.1016/S0022-3913(99)80002-X. PMid:10095205
» http://dx.doi.org/10.1016/S0022-3913(99)80002-X -
16Morgano SM, Milot P. Clinical success of cast metal posts and cores. J Prosthet Dent. 1993 July;70(1):11-6. http://dx.doi.org/10.1016/0022-3913(93)90030-R. PMid:8366452
» http://dx.doi.org/10.1016/0022-3913(93)90030-R -
17Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay FR, Breschi L, et al. A randomized controlled trial of endodontically treated and restored premolars. J Dent Res. 2012 July;91(7 Suppl):72S-78S. http://dx.doi.org/10.1177/0022034512447949. PMid:22699672
» http://dx.doi.org/10.1177/0022034512447949 -
18Fokkinga WA, Kreulen CM, Bronkhorst EM, Creugers NH. Up to 17-year controlled clinical study on post-and-cores and covering crowns. J Dent. 2007 Oct;35(10):778-86. http://dx.doi.org/10.1016/j.jdent.2007.07.006. PMid:17716800
» http://dx.doi.org/10.1016/j.jdent.2007.07.006 -
19Hunter AJ, Feiglin B, Williams JF. Effects of post placement on endodontically treated teeth. J Prosthet Dent. 1989 Aug;62(2):166-72. http://dx.doi.org/10.1016/0022-3913(89)90306-5. PMid:2668511
» http://dx.doi.org/10.1016/0022-3913(89)90306-5 -
20Trope M, Maltz DO, Tronstad L. Resistance to fracture of restored endodontically treated teeth. Endod Dent Traumatol. 1985 June;1(3):108-11. http://dx.doi.org/10.1111/j.1600-9657.1985.tb00571.x. PMid:3893998
» http://dx.doi.org/10.1111/j.1600-9657.1985.tb00571.x
Publication Dates
-
Publication in this collection
Mar-Apr 2015
History
-
Received
16 May 2014 -
Accepted
07 Oct 2014