Saudi Endodontic Journal

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 9  |  Issue : 1  |  Page : 14--20

Restorative methods to rehabilitate endodontically treated posterior teeth by students and new graduates of King Saud University: A survey study


Sahar A AlZain 
 Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia

Correspondence Address:
Dr. Sahar A AlZain
Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh
Saudi Arabia

Abstract

Aim: The aim of the study was to evaluate the efficiency of dental students and new graduates of College of Dentistry, King Saud University, in Riyadh, Saudi Arabia, to select the appropriate methods of restoring endodontically treated posterior teeth (ETPT) at different conditions of remaining sound tooth structure. Materials and Methods: A questionnaire was distributed among the 4th- and 5th-year dental students and new graduates. Respondents were requested to indicate their gender and level of education and to select the preferred restoration of ETPT at different conditions. Results were analyzed using one-way frequency and two-way cross-tabulations. Results: At >50% tooth remaining (condition A), 39.9% of the respondents preferred to use an amalgam restoration, while 30.9% preferred to use a restoration followed by a crown at 50% of remaining tooth (condition B). At <50% tooth remaining (condition C), 74.6% preferred to use a cast post-and-core and a crown. Respondents changed their choices of restoration to more advanced ones when teeth served as abutments for fixed or removable prostheses. Chi-square analysis demonstrated a statistically significant relationship between the selected restorative method at condition A and both gender (P = 0.045) and level of education (P = 0.001), between the method of restoration at condition B and both the gender (P = 0.000) and the level of education (P = 0.003), and between the selected restorative method at condition C and the level of education (P = 0.000). Conclusions: Respondents demonstrated a high knowledge when selecting the appropriate method of restoring ETPT at different clinical conditions.



How to cite this article:
AlZain SA. Restorative methods to rehabilitate endodontically treated posterior teeth by students and new graduates of King Saud University: A survey study.Saudi Endod J 2019;9:14-20


How to cite this URL:
AlZain SA. Restorative methods to rehabilitate endodontically treated posterior teeth by students and new graduates of King Saud University: A survey study. Saudi Endod J [serial online] 2019 [cited 2019 Feb 21 ];9:14-20
Available from: http://www.saudiendodj.com/text.asp?2019/9/1/14/249591


Full Text

 Introduction



The prognosis of endodontically treated teeth (ETT) depends not only on the outcomes of endodontic treatment but also on the selected definitive restoration depending on the amount of remaining coronal tooth structure.

In the literature, different restorations of endodontically treated posterior teeth (ETPT) were recommended depending on the amount of destruction of the tooth structure. In posterior teeth, access cavity preparations were reported to result in a great flexure.[1] However, Gonzaga et al.[2] stated that ETPT in which the majority of coronal tooth structure remained intact except for the access opening cavity were found to be best restored with only amalgam restoration. When occlusal access cavities of the premolars were restored with glass ionomer and composite, fracture resistance was found to be close to that of the intact teeth; however, when those premolars fractured, they were found to be nonrestorable.[3] It was recommended that posterior teeth with a small cavity size (Class I, Class II mesio-occlusal/disto-occlusal, or Class II mesio-occluso-distal [MOD]) be restored using a conservative approach such as direct composite or inlay restorations.[4] The fracture strength of endodontically treated (ET) maxillary premolars, with MOD and access cavities, restored with conventional amalgam, bonded amalgam, and composite resin, did not differ significantly.[5] Restorations of ETPT with cusp coverage should be considered to assure long-term success of the tooth.[1] A large cavity size should be restored with onlay restoration.[4]

A greater dentin surface area is available in the posterior teeth than that in the anterior teeth. Hence, a bonded build-up core is preferable to the conventional post-and-core systems.[6] Sorrentino et al.[7] stated that “direct restoration of premolars with MOD cavity with fiber post and composite resin without crown coverage might be considered a valid alternative to the unconservative crown restoration.” However, bonded restoration with no crown was found to adversely affect the long-term success of the restoration in patients who had excessive biting forces or para-functional habits.[7]

Teeth with a remaining intermediary coronal tooth structure often required the use of prefabricated fiber posts and direct composite restorations.[2],[4]

Extensive loss of coronal tooth structure resulted in an increase in cusp deflection.[8] When little or no coronal tooth structure remained, the use of intra-canal post-and-core was considered mandatory to retain the coronal restoration.[2],[4] However, molars sometimes do not require post-and-core because of their bulk tooth structure and large pulp chamber that can retain a core.[2] Moreover, molars are more subject to vertical forces due to their position in the dental arch. On the other hand, premolars have less amount of coronal tooth structure and a smaller pulp chamber than molars. Thus, they require posts and cores.[2] However, some anatomical features should be considered during intra-radicular preparation of premolars such as root taper and curvature, thin mesiodistal root structure, and proximal invaginations.[2]

The 2-mm ferrule effect in the ET premolars was found to positively affect the fracture strength of the fiber post.[9] It was found that post length in the canal did not improve the fracture strength of the post when the ferrule length was 2 mm.[9]

Clinical experience as well as theoretical knowledge of the most appropriate method of restoration of ETT with different clinical conditions by dental students and new graduates is mandatory. Currently, there is no published data concerning Saudi dental students and new graduates on this topic. Therefore, the purpose of this study was to evaluate the efficiency of dental students and new graduates of College of Dentistry at King Saud University in Riyadh, Saudi Arabia, to select the appropriate methods of restoring ETPT at different conditions of remaining sound tooth structure.

 Materials and Methods



A questionnaire was designed, validated, and distributed among the 4th- and 5th-year dental students and new graduates of the College of Dentistry, King Saud University, in Riyadh, Saudi Arabia as part of course requirement. Respondents were directly approached and asked to respond to the questionnaire. Questionnaires were then collected, and the response rate was 98%. Respondents were asked to indicate their gender and level of education. Only students “at 4th- and 5th-year of dental education” who were pursuing clinical training in prosthodontics were included in this study. Students were approached at the end of the academic year for their responses based on their theoretical background and clinical experience throughout the year. The questionnaire contained different restorative treatment methods of restoration of ETPT at different conditions (percentages) of remaining sound tooth structure (>50%, =50%, and <50%). One or more of these conditions (percentages) were used in some studies as a guide to restore teeth.[1],[4] Respondents were asked to indicate their preferred restorative method of those teeth. They were also asked to indicate whether their chosen method would change if the same tooth at the same condition of remaining sound tooth structure was used as an abutment for fixed or removable partial dentures (FPDs/RPDs). A total of 233 questionnaires were collected.

Statistical analysis

The statistical analysis was performed using IBM Statistical Package for the Social Sciences (IBM SPSS version 20) (Chicago, IL, USA). One-way frequency tables were generated to summarize the responses. Two-way cross-tabulations were analyzed to show the associations between the preferred method of restoration and the gender and level of education.

 Results



Condition A (more than 50% of sound tooth structure remaining)

Results showed that 39.9% of the respondents preferred to use only an amalgam restoration and 25.3% selected to use a tooth-colored restoration [Table 1]. Female (47.1%) and 4th-year students (56.4%) preferred to use an amalgam restoration, while male (28.7%) and 5th-year students (33.3%) preferred to use a tooth-colored restoration [Table 2] and [Table 3]. Chi-square analysis demonstrated a statistically significant relationship between the selected restorative method and gender (P = 0.045) and level of education (P = 0.001). When the same tooth is to be used as an abutment for an FPD/RPD, respondents preferred to restore it with amalgam/tooth-colored restorations followed by crown restorations (33.9%) [Table 4]. This method was preferred more by male (36.8%) and 4th- and 5th-year students (33.8% and 39.3%, respectively) [Table 5] and [Table 6]. Chi-square analysis demonstrated a statistically significant relationship only between the selected restorative method and the level of education only when the tooth is to be used as an abutment for FPD/RPD (P = 0.015).{Table 1}{Table 2}{Table 3}{Table 4}{Table 5}{Table 6}

Condition B (about 50% of sound tooth structure remaining)

The majority of respondents (30.9%) preferred to restore the teeth with amalgam/tooth-colored restoration followed by a crown restoration [Table 1]. This selection was preferred more by female students (35.6%) and new graduates (41.3%) [Table 2] and [Table 3]. Moreover, a prefabricated stainless steel post with a build-up core material (amalgam/tooth-colored) and a crown were preferred by 22.3% of respondents more by male respondents (28.7%) and 5th-year students (36.6%). Chi-square analysis demonstrated a statistically significant relationship between the selected restorative method and both the gender (P = 0.000) and the level of education (P = 0.003). When the same tooth is to be used as an abutment for FPD/RPD, most of respondents (39.3%) preferred to use a prefabricated stainless steel post with a build-up core material and a crown [Table 4]. This restoration was preferred more by male (43.6%) and 5th-year students (55.7%) [Table 5] and [Table 6]. Chi-square analysis demonstrated a statistically significant relationship only between the selected restorative method and the level of education only when the tooth is to be used as an abutment for FPD/RPD (P = 0.023).

Condition C (less than 50% of sound tooth structure remaining)

Results showed that 74.6% of the respondents preferred to use a cast post-and-core and a crown restoration [Table 1]. This method was comparably preferred by both genders and more by 5th-year students (92.2%) [Table 2] and [Table 3]. Chi-square analysis demonstrated a statistically significant relationship between the selected restorative method and the level of education (P = 0.000). When the same tooth is to be used as an abutment for FPD/RPD, 85.2% of respondents preferred to use a cast post-and-core and a crown restoration [Table 4]. This method was comparably preferred by both genders [Table 5] and more by 5th-year students (93.4%) [Table 6]. No statistically significant relationship existed between the selected restoration and the gender or level of education when the tooth is to be used as an abutment for FPD/RPD (P = 0.051).

 Discussion



The majority of respondents in the present study selected to restore ETPT that had a large amount of coronal tooth structure remaining with an amalgam and tooth-colored restorations (39.9% and 25.3%, respectively). This was supported by the study of Gonzaga et al.,[2] who recommended using only a direct composite resin or an amalgam restoration to restore the endodontic access, with very good prognosis.[2] They stated that “when tooth-reinforcing structures, such as marginal ridges, are still present and the tooth displays a deep pulp chamber, only a composite resin restoration may be used without the need of an intra-radicular post.”[2]

Onlay restoration was used in this study at conditions A and B by 9.87% and 10.3%, respectively. It was found that onlay restorations with cusps coverage may be used to restore ETT in which one wall was present and could be preserved.[2]

The amalgam or the tooth-colored restoration was further protected by a crown at conditions A (18.4%) and B (30.9%) in this study. Full-coverage restoration for ETPT exhibited a higher success rate than that of teeth with intra-coronal restoration.[10]

In the present study, the use of posts (either prefabricated or custom cast) was preferred to restore ETT at conditions B and C more than those at condition A. It was stated that “posts may not be used for restoration of ETT unless there is an extensive destruction of coronal tooth structure, resulting in an insufficient retention for the core is obvious.”[4] In this study, a fiber post was used at condition B with and without a crown (6% and 12%, respectively). The highest stress concentration was found when using a cast post-and-core.[11] Metal and zirconia are stiffer than dentin and have higher moduli of elasticity. Thus, they can increase the risk of a vertical root fracture that is not repairable.[6] On the other hand, a fiber-reinforced post provides stress distribution similar to a sound tooth with a modulus of elasticity closer to dentin.[6],[12] A fiber post was found to induce less stress concentration at the apical area, whereas more stress concentration was reported in the cervical region.[6] This may lead to post fracture, debonding of core materials, and loss of retention all of which are repairable.[6] However, Zicari et al.[13] did a clinical study and concluded that both cast gold and glass fiber post-and-core performed well after 3 years of follow-up.

It is important to consider the ferrule effect when preparing ETT. It is actually achieved by having 2 mm of coronal tooth structure above the preparation margin. It optimizes tooth biomechanical behavior.[4],[8] The ferrule effect greatly increases the strength of the tooth and prevents root fractures.[4],[8],[14] It embraces the coronal aspect of the tooth by the encircling band of cast metal.

A fiber-reinforced composite restoration with the polyethylene ribbon fibers was introduced to restore severely damaged ETPT. It resulted in a stress distribution that is more similar to that in a natural tooth.[12],[15] Inserting the polyethylene ribbon fiber buccolingually on the occlusal surface of ET premolars with MOD cavities resulted in increased fracture strength.[16]

Goga and Purton[8] recommended to avoid using ETT as distal abutments of cantilever FPDs. Any increase in stresses in the abutments compromises the biologic and restorative structures.[11] Meyenberg[6] concluded that metallic posts are preferred over fiber posts to restore abutments with large defects that require crown restorations in long-span FPDs or in cases in which heavy loads are expected. In the present study, more respondents preferred to use cast post-and-core and crown restorations to restore ETT serving as abutments for FPDs/RPDs at condition C (85.2%) than those not serving as abutments for any prostheses (74.6%). This reflected the respondents' awareness of the need to give more attention to those teeth serving as abutments for FPDs/RPDs.

The amount of remaining coronal tooth structure of ETT is very critical when the tooth is used an abutment for an RPD. The possible need for post placement should be considered.[8] However, regular maintenance recalls were strongly recommended.[8] Respondents in the present study preferred to change their restorative methods of ETT at all conditions when teeth would serve as abutments for FPRs/RPDs to more advanced ones. A statistically significant relationship existed between the selected restorative method and the level of education at conditions A and B.

In a survey study of 438 ETT (anterior and posterior teeth), adequate coronal restorations demonstrated significantly better periapical status (82.2%) than those of inadequate coronal restorations (37.2%).[17] Both well-performed endodontic and well-sealing restorative treatment of teeth play a significant role in obtaining an optimal success rate of ETT.[17]

In this study, the respondents' knowledge of the most appropriate restorative method of ETT with different amounts of remaining sound tooth structure was evident. The preferred restorative method of ETT may be influenced by both by gender and level of the education. A statistically significant relationship existed between the preferred method and both the gender and level of education at conditions A and B and level of education at conditions C.

The decision to maintain an endodontically involved tooth or do extraction is complex, so each patient should be examined and evaluated to come-up with a long-term treatment outcome.[18]

In general, the clinician should carefully evaluate and consider all clinical and radiographic factors to provide the best restorative treatment for ETT, assuring a good prognosis and higher clinical longevity.

 Conclusions



The results of this study showed that selection of the most appropriate restorative method of ETPT, at different clinical conditions, by students and new graduates of King Saud University was evident. A periodic evaluation of clinical experiences of students and new graduates is recommended to assure proper delivery of dental treatments.

Acknowledgment

I acknowledge Mr. Nassr Mefleh, the Biostatistician at the College of Dentistry Research Center (CDRC), for his help in the statistical analysis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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