A survey assessing the knowledge and perception of dental practitioners on the need for prophylactic endodontic treatment in abutment teeth for fixed partial dentures.

Background: Tooth preparation for fixed prosthodontic procedures often induces enough thermal or mechanical stresses on the pulp. The extent of pulpal injury and ability to repair depends on factors like amount of remaining dentin, extent of heat produced, and permeability of dentinal tubules. However, there is no infallible method to predict the pulpal response and so the treatment outcome. Aim: This survey tries to assess the knowledge and perception among dental practitioners on the need for prophylactic endodontic therapy in abutment teeth for fixed partial denture (FPD). Setting and Design: Questionnaire-based survey. Methodology: An observational study was then conducted among 303 dental practitioners in the state of Tamil Nadu and 250 participants responded. Statistical Analysis Used: Descriptive statistics and multiple linear regression analysis. Results and
Conclusion: The survey further imparts light on the clinical outcomes that help minimize the incidence of biological failure underneath a FPD. Copyright:

INTRODUCTION

Tooth preparation for fixed partial denture (FPD) often generates thermal and mechanical stimuli to the pulp.[1] Intensity of these stimuli and the extent of injury caused to the pulp and surrounding tissues is still unclear. For a clinician, it is important to understand these factors and determine whether a particular clinical situation calls for a minimally traumatic tooth preparation procedure or an endodontic treatment prior to the procedure.[2] Comprehensive knowledge and extensive experience in handling a variety of challenging clinical outcomes go hand in hand in providing optimal dental care with fool proof evidence. This article is a survey on the need for prophylactic endodontic therapy before performing tooth preparation for FPD.

Pulp–dentin complex is the term used to ascertain the physiologic nature of dentin and pulp functioning as a single unit. The net response of pulp to operative procedures is the result of complex interaction of multiple factors including mechanical trauma to the odontoblastic process, thermal stimulation of the pulp, amount of remaining dentin present, and dentinal tubular permeability.[3] Survival of odontoblast underneath the site of injury is crucial for pulp vitality and dentin repair. However, the nature of insult, whether of sudden onset (cavity preparation) or gradual (caries) is also of great importance. Trauma during cavity preparation is the main determinant of the extent of odontoblast injury and not the effect of chemical insults from restorative materials.[4]

Coupled with far-reaching clinical expertise and extensive understanding of molecular changes in pulp dentin complex, this article tries to address the long existing dilemma in dentistry and further enlighten us on the contemporary philosophies pertaining to tooth preparation and clinical decision making.

METHODOLOGY

Study design

The survey questionnaire was drafted, and validation process was carried out by giving out the first draft to ten professional experts. Experts were chosen based on the field with the highest frequency of procedures performed. After a week, the first drafts were collected from the experts and Individual–Content Validity Index (I-CVI) was calculated. Items having I-CVI <0.75 were removed from the questionnaire and were replaced with new questions suggested by the panels. Modifications were made to the first draft, and a second questionnaire was generated and distributed to the practitioners. A pilot study was performed by distributing the survey to 30 dental practitioners to calculate the sample size.

A cross-sectional observational study was then conducted among 303 dental practitioners in the state of Tamil Nadu, India. A confidential questionnaire was then prepared and distributed to 303 dental practitioners registered with the dental council practicing in private clinics and dental institutions, either through post or handling in person. A letter describing the objectives of the study and requesting for consent was attached to the questionnaire. Out of 303 questionnaires sent, 250 were filled and returned within a month. The confidentiality of all the participants was maintained throughout the study. Exclusion criteria included dental practitioners retired from clinical practice, and dentists who did not hold a current practising certificate.

The questionnaire was designed to collect information in three sections, namely, a sociodemographic profile of the participants, self-assessed perceived knowledge regarding the need for prophylactic endodontic treatment prior to FPD, and questions based on the perception regarding the management of the same. The collected data were analyzed and discussed in accordance with the recent developments pertaining to research. An E-mail reminder was sent 4 weeks after the questionnaire was sent to all the nonrespondents.

Statistical analysis

Microsoft Excel was used for data entry and SPSS software (SPSS for Windows version 18.0; IBM Malaysia, Selangor, Malaysia) was used for data analysis. Descriptive statistics like frequency and percentage were calculated for categorical variables. The mean, standard deviation (SD), and range were calculated for quantitative variables. Regarding knowledge questions, score “1” was given to the correct answer and score “zero 0” was given to the wrong answer or those who answered, “not sure.” Total score was computed and converted to percentage. The mean and its 95% confidence interval (CI) in each demographic group of practicing dentists is described in the bar graph. Multiple linear regression analysis was done to determine the association between gender, degree, clinical practice year, and knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis among practicing dentists. Level of significance was set at 0.05.

RESULTS AND DISCUSSION

Data analysis

Microsoft Excel was used for data entry and SPSS version 18.0 was used for data analysis. Descriptive statistics such as frequency and percentage were calculated for categorical variables while mean, SD, and range were calculated for quantitative variables. Regarding knowledge questions, score “1” was given to the correct answer and score “zero 0” was given to the wrong answer or those who answered, “not sure.” Total score was computed and converted to percentage. The mean and its 95% CI in each demographic group of practicing dentists also described in bar graph. Multiple linear regression analysis was also used to determine the association between gender, degree, clinical practice year, and knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis among practicing dentists. Level of significance was set at 0.05.

Demographic profile of the participants comprises 32.5% male respondents and 67.5% female respondents. Among the respondents, 55% had a bachelor's degree in dentistry while 45% had master's degree. The clinical practice years ranged from newly joined (0 year) to 25 years, while the mean was 4.0 years (SD 4.1).

Table 1 shows that 35.8% of the dentists recommended prophylactic endodontic therapy on abutment teeth for fixed prosthesis. Among the dentists, 24.8% never encounter a biological failure (pulp necrosis/Irreversible pulpitis) in abutment teeth for FPDs, 70.8% encountered <5 out of 10 cases, and 5% encountered more than 5 out of 10 cases. Regarding knowledge about prophylactic endodontic therapy, 70% of the participants correctly answered about clinical situation, in which prophylactic endodontic therapy was advised, while 21.7% had correct answer about common reason for failure, 12.6% about most common teeth to develop endodontic complication following tooth preparation, 63.9% about pulpal changes during tooth preparation, 60.8% about use of high speed hand pieces with sufficient air water spray, and 20% about blowing air on a prepared tooth which can induce odontoblastic cell death. 35% of the respondents were aware of Immediate Dentin Sealing (IDS), and among them 52.6% knew what IDS was. The knowledge score was ranged from 0 to 100 in this study; however, the mean knowledge score was 41.6 (SD 18.5) [Table 1].

Table 1

Prophylactic endodontic therapy on abutment teeth for fixed prosthesis and knowledge about it among practicing dentists (n=120)

Question	n (%)
Do you perform pre-operative radiographic assessment of abutment teeth before tooth preparation for FPDs
Yes	103 (85.8)
No	17 (14.2)
Not regularly	0
Do you recommend prophylactic endodontic therapy on abutment teeth for FPDs
Yes	43 (35.8)
No	47 (39.2)
Not sure	30 (25.0)
In which clinical situation do you advice prophylactic endodontic therapy before tooth preparations?
Attrited teeth, rotated teeth and teeth with pulpal exposure*	84 (70.0)
All mandibular incisors due to smaller dimension	25 (21.2)
Any abutment tooth for FPD	9 (7.6)
What is the most common reason for failure of FPD?
Loss of retention*	26 (21.7)
Loss of pulp vitality/irreversible pulpitis or carious involvement of abutment teeth	34 (28.3)
Periodontal breakdown or fracture of FPD	60 (50.0)
Which are the most common teeth to develop endodontic complication following tooth preparation when an unblemished abutment (no history of trauma, no restoration/caries) was used?
Maxillary and mandibular anterior*	15 (12.6)
Maxillary and mandibular pre-molar	69 (58.0)
Maxillary and mandibular molars	35 (29.4)
Increased incidence of pulpal necrosis/irreversible pulpitis following crown preparation, in your clinical practice, was observed in?a
Anterior FPDs	54 (48.2)
Posterior FPDs	31 (27.7)
Single crowns	28 (25.0)
How often do you encounter a biological failure (pulp necrosis/irriversible pulpitis) in abutment teeth for FPDs”?
0 out of 10 cases	29 (24.2)
<5 out of 10 cases	85 (70.8)
>5 out of 10 case	6 (5.0)
Pulpal changes during tooth preparation can occur due to
Heat, desiccation and vibration	22 (18.5)
Proximity to the pulp	21 (17.6)
All of the above*	76 (63.9)
How often do you change your burs?
After every single preparation	16 (13.5)
After 5 but before 10 preparations	88 (73.9)
>10 preparations	15 (12.6)
Use of high speed hand pieces with sufficient air water spray?
Increases the pulpal temperature	19 (15.8)
Decreases the pulpal temperature*	73 (60.8)
Not sure	28 (23.3)
Blowing air on a prepared tooth can induce odontoblastic cell death?
Yes	45 (37.5)
No*	24 (20.0)
Not sure	51 (42.5)
Do you always place provisional restoration after tooth preparation for FPD?
Yes	82 (68.3)
No	38 (31.7)
Not regularly	0
Are you aware of IDS?
Yes	42 (35.0)
No	75 (62.5)
Not sure	3 (2.5)
What is IDS? (n=38)
Application of dentin bonding agent to freshly cut dentin prior impression making*	20 (52.6)
Application of dentin bonding agent to freshly cut dentin after impression making	10 (26.3)
Application of flowable composite to freshly cut dentin prior to impression making	8 (21.1)
Do you perform IDS every time after tooth preparation? (n=42)
Yes	14 (33.3)
No	28 (66.7)
Not regularly	0
Knowledge total score
Mean (SD)	41.6 (18.5)
Minimum-maximum	0-100

*Correct answer, aMultiple answers. FPDs: Fixed partial dentures, IDS: Immediate dentin sealing, SD: Standard deviation

Graphs 1 and 2 show the mean and 95% CI of knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis between different gender and degree, respectively.

Graph 1

Knowledge regarding prophylactic endodontic therapy on abutment teeth for fixed prosthesis between male and female

Graph 2

Knowledge regarding prophylactic endodontic therapy on abutment teeth for fixed prosthesis between BDS and MDS

Multiple linear regression was used to determine the association between gender, degree, clinical practice year, and knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis among practicing dentists. There was no evidence of multicollinearity, as assessed by tolerance values >0.1. The multiple linear regression model was not statistically significant predicting the outcome (F (3.113) = 1.649; P = 0.182; adjusted R2= 0.016). There were no statistically significant association between gender (regression coefficient - 3.65, 95% CI - 11.15–3.86), degree (regression coefficient - 6.01, 95% CI - 13.90–1.88), clinical practice year (regression coefficient 0.91, 95% CI - 0.07–1.90) and knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis [Table 2].

Table 2

The association between gender, degree, clinical practice year and knowledge about prophylactic endodontic therapy on abutment teeth for fixed prosthesis among practicing dentists

Variable	B (95% CI)	SE	P
Gender
Male	Reference	3.79	0.338
Female	−3.65 (−11.15-3.86)
Degree
BDS	Reference	3.98	0.134
MDS	−6.01 (−13.90-1.88)
Clinical practice years	0.91 (−0.07-1.90)	0.50	0.069

B=Regression coefficient, CI=Confidence interval, SE=Standard error

DISCUSSION

The present study investigated the knowledge and the perception of dental practitioners on the need for prophylactic endodontic treatment in teeth used as abutment for FPD. The intent of the study was to provide a clinical evidence base, derived from genuine experiences in dental practice, to help guide the practitioner in planning the treatment protocol. Maximum proportion of participants confirmed to performing preoperative assessment of the abutment teeth before commencing the procedure and 35.8% of them recommended prophylactic endodontic therapy on abutment teeth for fixed prosthesis whereas 39.2% chose to disagree. According to Kannan et al., who studied the methodology for fabrication of FPD, 35% of practitioners advocated intentional root canal treatment (RCT) for abutment teeth which were symptomatic, and a marginally equal 32% advised the for all cases to ensure longevity.[5] In a previous study conducted by Cheung et al. on patients with fixed bridges, 20 of 169 (15.6%) bridges examined had failed due to endodontic reasons.[6]

On assessment of the knowledge of dental practitioners, 70% of the participants correctly answered about clinical situation in which prophylactic endodontic therapy was advised, which could be attributed to the various guidelines reported in literature,[789101112131415] that rationalize and affect the prognosis of the FPD such as crown-root ratio, periodontal health, root surface area, morphology, cross section, and convergence/divergence of roots. On inquired about the reasons for failure of FPD, only 21.7% had recognized the correct response. Goodacre et al. reviewed the complications arising from FPDs and concluded that there were multiple studies reporting the different complications, but did not provide data regarding the reasons for failure or any information about complications.[16] In another retrospective study, it was suggested that tooth reduction procedures combined with air coolant from the dental handpiece could simply assure minimal damage to the pulp.[17]

The survey further provides clinical insight on the extent and incidence of pulpal necrosis following tooth preparation for FPD. According to the survey maxillary premolars and molars (58%) are the most common to develop pulpal necrosis following tooth preparation, in contrast, the mandibular incisors (15%) with smaller dimensions are minimally affected following tooth preparation. In contrast to the current research, it has been reported earlier that there was a higher rate of pulpal necrosis when maxillary anterior teeth were used as bridge abutments compared to other tooth types.[6] About 70% of doctors report that out of 10 FPDs delivered, 1–5 cases have reported hypersensitivity or other pulpal symptoms.

IDS consists of application of dentin bonding agent to the freshly cut dentin following tooth preparation for indirect restorations before impression making.[18] The procedure is said to limit bacterial penetration of dentinal tubules and prevent hypersensitivity during the term the provisional restoration was given.[19] However, in the current survey it was observed that about 75% of practitioners are still unaware of the procedure. In addition, 67% of professionals aware of IDS have reported failure to perform the same in clinical practice. This may be the reason for increased incidence of pulpal symptoms following tooth preparation.

Although practitioners provided mixed response for performing intentional endodontic therapy, certain clinical conditions often necessitate intentional root canal therapy. The conditions include doubtful pulps indicated for fixed prosthodontic procedures, sound teeth scheduled to receive overdentures, calcific metamorphosis of the pulp leading to discoloration of clinical crown following trauma, teeth requiring root amputation for periodontal healing, surgical procedures for bone lesions of odontogenic or non-odontogenic origin approximating the root apex, tetracycline discoloration in teeth with absolutely normal pulp where intentional endodontic treatment followed by internal bleeding has been was advocated.[19]

CONCLUSION

This survey suggested that about 25% of the study population were unassertive whether to perform elective RCT or not, in abutment teeth for FPD. The survey tried to address all the factors that need to be considered before planning elective root canal procedures. The dental curriculum should also consider incorporating definitive guidelines for elective RCTs to help practitioners, in crucial decision making, when planning an FPD.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.