A survey of contemporary methods of restoring

endodontically treated teeth in Riyadh area-Part I: Anterior teeth

Sahar Sabbak, BDS, MSc , Amal Al-Qahtanr, BDS 
Huda Tulba, BDS
Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, KSA

Proper selection of a restoration for endodontically treated teeth is mandatory. This study was initiated to detect the frequency of preferred methods of restoring endodontically treated anterior teeth under different conditions. A questionnaire was distributed among prosthodontists and general practitioners in Riyadh area. They were also asked to indicate their year and institution of graduation, acquired degree and current institution. In the questionnaire, they were asked about their preferred restorative methods of the teeth under different clinical conditions. Responses from 150 dentists were collected and statistically analyzed. The results indicate that 71.3% of respondents preferred to use a composite restoration when more than 50% of sound tooth structure remains (condition A). When about 50% of sound tooth structure remains (condition B), most of the respondents preferred to use composite/crown (39.3%). However, when less than 50% of sound tooth structure remains (condition C), 79.3% of respondents preferred to use a cast post and core/crown. When the teeth are used as abutments for fixed or removable partial dentures (F/RPDs), the use of a more advanced methods of restorations is preferred. Other factors were found to affect the choice of treatment method. It can be concluded that most of respondents of this study are clinically capable of making proper decisions concerning the restoration of endodontically treated anterior teeth.

Loss of coronal tooth structure can occur as a result of trauma, caries, previous restoration and endodontic access procedure. This may range, from a very minimal access preparation of an intact tooth to a very extensive damage that endangers the longevity of the tooth itself.1 The restorative decision depends on factors like the amount of remaining sound tooth structure, the location of the tooth in the dental arch, the functional demands that are placed on the tooth and the need of this tooth to serve as an abutment for fixed or removable partial dentures.2,3 When coronal damage is minimal and the tooth is esthetically accepted, the complete coverage is not required, and a composite resin, glass ionomer or amalgam restoration is considered adequate.4-6 It has been shown repeatedly that the fracture resistance of an intact endodontically treated anterior tooth approaches that of an untreated tooth and that an intact anterior tooth with conservative endodontic access and intact marginal ridges does not require a post or coronal coverage.7,8 However, ElKhodery et al.9 indicated the importance of reinforcing endodontically treated anterior teeth even if they are sound and not carious. When a crown is indicated for esthetic reasons, the axial reduction combined with an endodontic access preparation frequently leaves insufficient sound dentin to support a crown especially if a metal-ceramic crown is planned. Therefore, a dowel core is probably needed. Ko et al.10 found that under vertical loading, posts reduce dentin stress substantially because they are under compression. As incisors and canines are rarely subjected to vertical loading, the reinforcement effects of posts seem to be doubtful in these teeth.10 When restoring endodontically treated anterior teeth with moderate damage and those with severe destruction, cast posts and cores are considered by several researchers as the restorative method of choice.11-13 Many restorative dentists base their decision-making process regarding restoration of endodontically treated teeth on past clinical experience rather than follow a specific protocol.4

The purpose of this survey study was to determine the frequency of the preferred methods of restoring endodontically treated anterior teeth at different conditions (percentages) of remaining sound tooth structure by prosthodontists and general practitioners in Riyadh area.    

A questionnaire was designed and distributed among prosthodontists and general practitioners who work in private and governmental clinics in Riyadh area. Respondents were asked to indicate their year and institution of graduation, obtained degree and current institution. The questionnaire contained different choices of restorative treatment methods of restoration of endodontically treated anterior teeth at different conditions (percentages) of remaining sound tooth structure (>50%: minimal coronal tooth structure is missing with no previous restoration, = 50%: up to one-half of the coronal tooth structure is missing with minor previously placed restorations and <50%: all or more than one-half of the coronal tooth structure is missing). Respondents were asked to indicate their preferred method of restoration of those teeth. They were also asked to indicate whether the chosen method would change if the same tooth at the same condition of remaining sound tooth structure were used as an abutment for fixed or removable partial dentures. Responses from 150 prosthodontists and general practitioners were collected. The data were entered into microcomputer using FOX PRO (Window ver. 2.5). A Statistical Package of Social Sciences (SPSS ver 7.5) was used for all computational purposes. One-way frequency tables were generated to summarize the responses. Two-way cross tabulation tables were computed to show the relationship between the variables.

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

Results showed that majority of respondents (71.3%) preferred to restore the tooth only with a tooth-colored restorative material (Table 1). The use of only a tooth-colored restorative material was preferred more by respondents who graduated in the 90s (82%) as shown in Table 2, more by graduates of Kingdom of Saudi Arabia (KSA) institution (79.5%) as shown in Table 3, more by those with Bachelor (BDS) degree (73.9%) as shown in Table 4 and more by governmental workers (80.8%) as shown in Table 5. Statistical analysis using Chi-square demonstrated a statistically significant relationship only between the year and institution of graduation and the current institution and the preferred restorative method. When the same tooth is used as an abutment for fixed or removable partial dentures (F/RPDs), 51.9% of respondents preferred to protect the tooth with a crown (Table 6). This is also used more by respondents who graduated in the 90s (54.7%) as shown in Table 7, almost equally by graduates of both institutions (Table 8), more by those with BDS degree (53.2%) as shown in Table 9 and more by private practice workers (Table 10).

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

Majority of respondents preferred to use the tooth-colored restorative material/crown and a prefabricated post and restorative material/crown 39.3% and 31.3%, respectively (Table 1). The percentage of those who preferred to use a tooth-colored restorative material was significantly reduced at this condition to 2.7%. The use of a tooth-colored restorative material/crown was preferred more by respondents who graduated in the 90s (46.1%) as seen in Table 2, more by graduates of  KSA institution (40.4%) as seen in Table 3, more by general practitioners (45.2%) as seen in Table 4 and more by governmental workers 42.3%) as seen in Table 5. However, when the same tooth is used as an abutment for F/RPDs, a greater percentage of respondents (43.2%) preferred to use a prefabricated post and a restorative material core/crown (Table 6). This treatment method is preferred more by those who graduated in the 80s (50%) as seen in Table 7, more by graduates of institutions other than KSA (46.2%) as seen in Table 8, almost equally by respondents with BDS and MSc/PhD degrees (43.5% and 42.1%, respectively) as seen in Table 9 and more by governmental workers (44.3%) as seen in Table 10. The Chi-square analysis demonstrated a statistically significant relationship only between the degree and the choice of treatment method whether or not the teeth are used as abutments for F/RPDs (P>0.05).       

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

At this condition, most of respondents preferred to use a cast post and core/crown (79.3%) as seen in Table 1. This percentage increases to 91.1% when the teeth are used as abutments for F/RPDs (Table 6). Whether or not the tooth was used as an abutment for F/RPDs, this restorative method is used more by respondents who graduated in the 90s (Tables 2 & 7), more by graduates of KSA institution (Tables 3 & 8), more by respondents with MSc/PhD degree (Tables 4 & 9) and more by governmental workers (Tables 5 & 10).

In this study, 95.3% of respondents believed that multiple factors like: patient medical condition, patient financial support and cooperation, time factor, laboratory support and availability of required materials may affect their choice of treatment method.

Discussion

The finding of this study is supported by other studies which stated that when coronal damage is minimal, a conservative treatment in a form of composite resin, glass ionomer or amalgam restorations should be considered.1,2,5,6 In the present study, the importance of protecting teeth that serve as abutments of F/RPDs by fabricating extra-coronal restorations reflects the awareness of the clinicians about the extra load and additional stresses that are exerted on such teeth.

A prefabricated post with a restorative material core build-up is widely used. Christensen14 stated that core materials that are used under crowns and replace most of the coronal portion of the tooth should have at least the compressive strength of the tooth structure being replaced (40,000 psi). At this time, only two types of core materials were found to meet this requirement: composite resin (~ 40,000 psi) and silver amalgam (~ 65,000 psi).14 It was found that amalgam cores under artificial crowns had the lowest rate of defects.15 Amalgam and composite cores recorded a statistically significant higher resistance to cyclic fatigue loading than reinforced glass ionomer cements.15 On the basis of strength, both resin composites and amalgam may be indicated for use as core materials while glass ionomer-based materials are not.16,17 Composite resin and silver amalgam should be bonded to tooth structure using dentin bonding materials to reduce leakage and increase retention to tooth structure.18 It is well known that a composite restoration is recommended for restoration of anterior teeth to avoid possible root staining by the amalgam restoration that could hinder esthetics.19  Several studies indicated the importance of placing a post in the root portion to attach the root structure to the core material that is being bonded to the remaining coronal tooth structure.1,2,4,5,7 The posts can be prefabricated or custom-cast. Prefabricated posts are best suited for circular canals, while custom-cast posts and cores possess superior adaptation to all root canals.2,4 Cast posts and cores do not require auxiliary retention such as pins to retain the core as in some prefabricated systems. On the other hand, a prefabricated post with a restorative material core  build-up  is  widely  used.  In  1987,  Brandal et al.13 reported the highest mean failure load of prefabricated post and composite buildup restorations of endodontically treated anterior teeth. Glass-ionomer/amalgam coronal-radicular buildups exhibited the lowest failure load.13 In a survey study in the United States, the majority of dentists used either cast posts exclusively or both cast posts and prefabricated posts in their practices.20 However, Morgano and Milot11 and, Morgano and Brackett12 considered cast posts and cores as the restorative method of choice for endodontically treated anterior teeth with moderate destruction. Fraga et al.21 reported a significantly higher resistance to fracture of single-rooted teeth restored with nickel-chromium cast posts and cores than that of single-rooted teeth restored with steel prefabricated posts. It was concluded that a cast post and core is indicated where alignment of the proposed crown is significantly different from the inclination of the canal, which is often the case with anterior teeth.22 In most of anterior teeth, there is an inadequate room for sufficient bulk of build up material around the post to provide a solid unit.22 Thus a cast post and core is required for restoring these teeth.22 In the present study, more percentages of respondents at condition B preferred to use a tooth-colored restorative material with and without a prefabricated post and a crown than those seen at condition A.  On the other hand, the use of only a tooth-colored restorative material is significantly reduced more than that at condition A. This also reflects the awareness of the respondents regarding the need of an additional reinforcement mean by using an occlusal coverage for replacement of the lost tooth structure. Several authors stated that if the tooth is significantly damaged, esthetically poor or serves as an abutment for F/RPDs, a complete coverage is indicated and the tooth will require a post and core for a crown retention and support.4,22 In this study, a high percentage of respondents of KSA institution preferred to protect the teeth that serve as abutments for F/RPDs by extra-coronal restorations. This can give a clear idea about attained high levels and proper treatment choices of graduates of KSA institution.

Authors are thankful to Dr. Nazeer Khan, Statistician of the Research Center, for his valuable help in the statistical analysis of data.