Abstract
Objectives
To investigate repairs of direct restorations by a group of Dutch general dental practitioners (GDPs) and its consequences on longevity of restorations.
Methods
Data set was based on dental records of patients attending 11 general dental practices (24 Dentists) in the Netherlands. Patients that received Class II Amalgam or Composite restorations were included in the study. The outcomes were considered in two levels: “Success” – When no intervention was necessary on the original restoration, it was considered clinically acceptable. “Survival” – Repaired restorations were considered clinically acceptable. Kaplan–Meier statistics and Multivariate Cox regression were used to assess restorations longevity and factors associated with failures (p < 0.05).
Results
59,722 restorations placed in 21,988 patients were analyzed. There was a wide variation in the amount of repairs among GDPs when a restoration had failed (Level 1). Repairs of multi-surface restorations were more frequent (p < 0.001). A total of 9253 restorations (Level 1) or 6897 restorations (Level 2) had failed in a 12-year observation time. “Success” and “Survival” of the restorations reached 65.92% (AFR = 4.08%) and 74.61% (AFR = 2.88%) at 10 years, respectively. Patient (age, removable denture) and tooth/treatment-related factors (molars, >2 restored surfaces, endodontic treatment, Amalgam) were identified as risk factors for failure (p < 0.001).
Conclusion
Overall, the GDPs showed satisfactory rates of restoration longevity over 10 years. Repair can increase the survival of restorations although, substantial differences exist among practitioners in repair frequency and AFRs. Molars, multi-surface restorations, presence of an endodontic treatment and a removable denture were identified as risk factors for failure.
Clinical significance
Repair, instead of total replacement of a defective restoration, is a Minimally Invasive procedure which can increase the survival of the original filling, reducing the risk for pulp complications and treatment costs.
1
Introduction
Placing dental restorations is core business for dentists all around the world. Dental restorations are most commonly placed due to caries or fracture and are often considered as ‘failed’ when a restoration does not meet certain standards that are designed by dental researchers and clinicians or when a patient experiences problems with a restored tooth like pain, unpleasant esthetic appearance etc. In case a restoration has been considered as ‘failed’ and a restorative intervention is needed, there are two possible options. In some cases it is decided to remove the entire restoration which is defined as replacement. Alternatively, only a part of the restoration is removed or a preparation is ground next to a restoration including the outline of the existing restoration. In those cases, the restorative intervention includes an additional restoration, which is defined as repair .
Although repair was traditionally often considered as ‘bad dentistry’ and not done by all dentists , nowadays repair is more and more considered as state-of-art as it limits the size of the restorative intervention, reduces the risk for complications and limits the costs of the intervention . For indirect restorations, Anusavice et al. defined repaired restorations, as an example due to porcelain fracture or endodontic treatment access opening, not as failures but as survived restorations. Accordingly, an indirect restoration that is still in function without any intervention is considered as a success and only totally replaced restorations (including extractions) are considered as real failures.
For direct restorations, the difference between survival and success is not defined yet in clinical studies as in most longevity studies, any intervention on a direct restoration is considered as failure . Meanwhile, dentists are implementing the concept of repair more and more in their clinical practice and modern dental schools are educating their undergraduates in repair techniques and indications .
Longevity of repair restorations, as expressed in the time between the repair restoration and the next intervention, is seldom investigated and includes several studies on interventions on restorations that are not failed yet (B scores for Ryge) showing good survival of small sized repairs. Two studies investigated actually failed restorations placed in some special general practices and demonstrated that repair can increase the longevity of dental restorations while at the same time the longevity of the repair restoration is less compared to the original restoration, depending from material and reason for repair .
Although from questionnaires it is known that dentists actually do repairs in their practices, the amount of repairs performed by general dental practitioners and the consequence for restoration survival is not known yet. The present study investigates among a group of general dental practitioners (GDPs) the amount of repairs and its consequences for longevity of class II restorations.
2
Materials and methods
2.1
Study design, characteristics and participants
This retrospective practice-based study was developed at the Department of Preventive and Restorative Dentistry, Radboud University, Nijmegen, The Netherlands. The data set was based on dental records of patients attending regularly eleven general dental practices. To be included in the analysis, each dentist from a general dental practice should contribute with a minimum of 200 restorations. The research protocol of the present study was approved by the local Ethics Committee METC (CMO file nr. 2013/483).
The target population was patients treated during the period between January 2000 and December 2011. To be eligible for the study, patients should have received at least one restoration performed with Composite Resin (CR) or Amalgam (Amg), placed in vital or endodontically treated posterior permanent teeth (pre-molars and molars). Only Class II restorations in two (MO; DO) or more surfaces (MOD; MOB; MODB; MODBL; MODBP; MODL; MODP; MOL; MOP) were included in the study. The patients should attend the dental clinic, at least, once a year for regular check-up. Restorations with missing information and uncertainties were excluded from the dataset.
2.2
Data collection
All the information was retrieved from Electronic Medical Files (EMF) of the patients. Data on the restorations were gathered anonymously by the dentists using software (Exquise, Kwadijk, NL), transformed into excel data files and sent to the research group. Individual (age; jaw; removable denture) and tooth/treatment related variables (tooth type; endodontic treatment; restorative material; n. surfaces) potentially associated with failure of restorations were investigated.
Date of restoration placement, dates of re-intervention (repair, replacement, crown, endo, extraction), as well as the last patient’s check-up were considered to calculate the survival of restorations and repaired restorations.
2.3
Outcome parameters
The outcomes were considered in two levels:
2.3.1
Level 1
When no intervention was necessary on the original restoration until the date of censoring (last check-up), it was considered clinically acceptable. A restoration was considered failed if at least one of the original surfaces in the restoration was re-restored later or if another treatment affecting the restoration was necessary (crown, endo, tooth extraction). An exception was made for mesial-occlusal (MO) and distal-occlusal (DO) class II restorations. When a MO restoration was placed as the first restoration and the intervention treatment was a DO restoration, analysis for the initial restoration was censored, because many MO and DO restorations in posterior teeth are two independent restorations (box type), and it would not be appropriate to qualify them all as failed. All restorations followed for less than 2 weeks were excluded.
2.3.2
Level 2
Repaired restorations were considered clinically acceptable. A “repaired restoration” occurred when, at least, one “original’ surface of the primary restoration remained in the ‘new’ intervention. Whenever all surfaces in the original restorations were replaced and a new treatment was necessary, it was considered as a failure and the date of the new treatment was considered as the failure time. In cases of multiple repairs at the same restoration (multiple restorative follow-ups), the surfaces of follow-ups were joined. Only at the time when the whole restoration was redone it was considered as failure.
Also, when teeth received an endodontic and prosthetic treatment (crown), or were extracted, it was categorized as a failure of the treatment.
2.4
Statistical analysis
The descriptive analysis provides the distribution summary according to the independent variables. Data collected from patient records were included in a database and analyzed using the Statistical Package for Social Sciences version 20.0 (SPSS Inc. Chicago, IL, USA, 2011). The annual failure rate (AFR) of the restorations and repaired restorations was calculated according to the formula: (1-y)z = (1-x), in which “y” expresses the mean AFR and “x” the total failure rate at “z” years. Longevity of restorations was assessed through Kaplan-Meier statistics.
Multivariate Cox regression models with shared frailty were performed to identify factors associated with failure of restorations. These models consider that observations within the same group (patient) are correlated, sharing the same frailty. Hazard ratios and their respective 95% confidence intervals (HR; 95%CI) were obtained.
2
Materials and methods
2.1
Study design, characteristics and participants
This retrospective practice-based study was developed at the Department of Preventive and Restorative Dentistry, Radboud University, Nijmegen, The Netherlands. The data set was based on dental records of patients attending regularly eleven general dental practices. To be included in the analysis, each dentist from a general dental practice should contribute with a minimum of 200 restorations. The research protocol of the present study was approved by the local Ethics Committee METC (CMO file nr. 2013/483).
The target population was patients treated during the period between January 2000 and December 2011. To be eligible for the study, patients should have received at least one restoration performed with Composite Resin (CR) or Amalgam (Amg), placed in vital or endodontically treated posterior permanent teeth (pre-molars and molars). Only Class II restorations in two (MO; DO) or more surfaces (MOD; MOB; MODB; MODBL; MODBP; MODL; MODP; MOL; MOP) were included in the study. The patients should attend the dental clinic, at least, once a year for regular check-up. Restorations with missing information and uncertainties were excluded from the dataset.
2.2
Data collection
All the information was retrieved from Electronic Medical Files (EMF) of the patients. Data on the restorations were gathered anonymously by the dentists using software (Exquise, Kwadijk, NL), transformed into excel data files and sent to the research group. Individual (age; jaw; removable denture) and tooth/treatment related variables (tooth type; endodontic treatment; restorative material; n. surfaces) potentially associated with failure of restorations were investigated.
Date of restoration placement, dates of re-intervention (repair, replacement, crown, endo, extraction), as well as the last patient’s check-up were considered to calculate the survival of restorations and repaired restorations.
2.3
Outcome parameters
The outcomes were considered in two levels:
2.3.1
Level 1
When no intervention was necessary on the original restoration until the date of censoring (last check-up), it was considered clinically acceptable. A restoration was considered failed if at least one of the original surfaces in the restoration was re-restored later or if another treatment affecting the restoration was necessary (crown, endo, tooth extraction). An exception was made for mesial-occlusal (MO) and distal-occlusal (DO) class II restorations. When a MO restoration was placed as the first restoration and the intervention treatment was a DO restoration, analysis for the initial restoration was censored, because many MO and DO restorations in posterior teeth are two independent restorations (box type), and it would not be appropriate to qualify them all as failed. All restorations followed for less than 2 weeks were excluded.
2.3.2
Level 2
Repaired restorations were considered clinically acceptable. A “repaired restoration” occurred when, at least, one “original’ surface of the primary restoration remained in the ‘new’ intervention. Whenever all surfaces in the original restorations were replaced and a new treatment was necessary, it was considered as a failure and the date of the new treatment was considered as the failure time. In cases of multiple repairs at the same restoration (multiple restorative follow-ups), the surfaces of follow-ups were joined. Only at the time when the whole restoration was redone it was considered as failure.
Also, when teeth received an endodontic and prosthetic treatment (crown), or were extracted, it was categorized as a failure of the treatment.
2.4
Statistical analysis
The descriptive analysis provides the distribution summary according to the independent variables. Data collected from patient records were included in a database and analyzed using the Statistical Package for Social Sciences version 20.0 (SPSS Inc. Chicago, IL, USA, 2011). The annual failure rate (AFR) of the restorations and repaired restorations was calculated according to the formula: (1-y)z = (1-x), in which “y” expresses the mean AFR and “x” the total failure rate at “z” years. Longevity of restorations was assessed through Kaplan-Meier statistics.
Multivariate Cox regression models with shared frailty were performed to identify factors associated with failure of restorations. These models consider that observations within the same group (patient) are correlated, sharing the same frailty. Hazard ratios and their respective 95% confidence intervals (HR; 95%CI) were obtained.
3
Results
In this retrospective practice-based study, the information was collected from 11 general dental practices, with 24 GDPs meeting the inclusion criteria of 200 contributing restorations. Data from 21,988 patients (10,652 male) with mean age of 38.2 (±14.8) years old were evaluated. A removable denture was present in 994 patients.
The analysis included 59,722 restorations (mean: 2.71 per patient) placed in premolars (28,883) and permanent molars (30,839). 112 restorations were placed in teeth with a reported status of endodontically treated. The observation period ranged from 2 weeks to 11.9 years.
Overall, 9253 restorations had failed (Level 1) over 12 years. When repair was not considered as a failure, 6897 restorations had failed (Level 2). Repairs were more frequent in multi-surface (1555) than in two-surface (801) restorations (p < 0.001). For repaired restorations, the mean observation time raised from 3.93 (±2.68) years (Level 1) to 6.91 (±3.02) years (Level 2).
A wide variation in annual failure rate was found between GDPs, ranging from 2.1% to 8.9% (5–10 years). Likewise, the percentage of repairs in case of a failed restoration varied among practitioners between 0 and 50%. The distribution of restorations placed by 24 dentists working in 11 practices, the failures and frequency of repairs and replacements, as well as AFRs at 5 and 10 years, are shown in Table 1 .
| a) Restorations placed by GDPs | b) Any intervention is a failure | c) Repair is not a failure | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Practice-Dentist id. | Restorations placed (n) | Failures (n) | Repairs (n) | Repairs (%) | Replacements (n) | Replacements (%) | Success | Annual failure rates | Survival | Annual failure rates | ||||||
| 5y | 10y | 1–5y | 1–10y | 5–10 y | 5y | 10y | 1–5y | 1–10y | 5–10 y | |||||||
| 1−1 | 305 | 16 | 8 | 50% | 8 | 50% | * | * | * | * | * | * | * | * | * | * |
| 1–2 | 1919 | 387 | 113 | 29% | 274 | 71% | 84% | 64% | 3,5% | 4,3% | 5,2% | 88% | 75% | 2,4% | 2,8% | 3,1% |
| 2−1 | 10212 | 1813 | 436 | 24% | 1377 | 76% | 80% | 61% | 4,4% | 4,8% | 5,2% | 85% | 71% | 3,2% | 3,4% | 3,7% |
| 2−2 | 2203 | 269 | 62 | 23% | 207 | 77% | 80% | * | 4,4% | * | * | 85% | * | 3,2% | * | * |
| 3−1 | 5192 | 1238 | 250 | 20% | 988 | 80% | 74% | 55% | 5,8% | 5,8% | 5,8% | 82% | 64% | 3,9% | 4,3% | 4,7% |
| 3−2 | 613 | 90 | 27 | 30% | 63 | 70% | 62% | * | 9,1% | * | * | 81% | * | 4,2% | * | * |
| 4−1 | 8061 | 1074 | 188 | 18% | 886 | 82% | 87% | 66% | 2,8% | 4,0% | 5,2% | 90% | 72% | 2,1% | 3,2% | 4,2% |
| 5−1 | 857 | 114 | 23 | 20% | 91 | 80% | 83% | * | 3,7% | * | * | 87% | * | 2,7% | * | * |
| 5−2 | 214 | 24 | 2 | 8% | 22 | 92% | 71% | * | 6,6% | * | * | 75% | * | 5,5% | * | * |
| 5−3 | 363 | 50 | 9 | 18% | 41 | 82% | 85% | * | 3,1% | * | * | 89% | * | 2,4% | * | * |
| 6−1 | 2637 | 590 | 253 | 43% | 337 | 57% | 80% | 54% | 4,3% | 6,0% | 7,7% | 90% | 72% | 2,1% | 3,3% | 4,5% |
| 7−1 | 1472 | 124 | 37 | 30% | 87 | 70% | 92% | 86% | 1,7% | 1,5% | 1,2% | 95% | 90% | 1,1% | 1,0% | 0,9% |
| 7−2 | 2604 | 249 | 104 | 42% | 145 | 58% | 86% | 69% | 2,9% | 3,6% | 4,3% | 92% | 85% | 1,6% | 1,6% | 1,6% |
| 8−1 | 4685 | 661 | 173 | 26% | 488 | 74% | 87% | 72% | 2,8% | 3,3% | 3,7% | 91% | 79% | 1,9% | 2,3% | 2,7% |
| 8−2 | 1657 | 333 | 61 | 18% | 272 | 82% | 60% | 38% | 9,6% | 9,2% | 8,9% | 68% | 46% | 7,4% | 7,5% | 7,5% |
| 8−3 | 211 | 33 | 15 | 45% | 18 | 55% | 77% | * | 5,1% | * | * | 88% | * | 2,5% | * | * |
| 8−4 | 252 | 30 | 7 | 23% | 23 | 77% | 85% | * | 3,2% | * | * | 89% | * | 2,3% | * | * |
| 8−5 | 510 | 16 | 0 | 0% | 16 | 100% | * | * | * | * | * | * | * | * | * | * |
| 8−6 | 1634 | 75 | 30 | 40% | 45 | 60% | 90% | * | 2,2% | * | * | 94% | * | 1,1% | * | * |
| 9−1 | 6217 | 1159 | 232 | 20% | 927 | 80% | 80% | 61% | 4,4% | 4,8% | 5,1% | 85% | 68% | 3,2% | 3,8% | 4,4% |
| 9−2 | 623 | 121 | 30 | 25% | 91 | 75% | 88% | 74% | 2,6% | 3,0% | 3,3% | 91% | 81% | 1,9% | 2,1% | 2,3% |
| 10−1 | 5010 | 625 | 229 | 37% | 396 | 63% | 90% | 78% | 2,2% | 2,4% | 2,7% | 93% | 87% | 1,4% | 1,4% | 1,3% |
| 10−2 | 441 | 2 | 2 | 100% | 0 | 0% | * | * | * | * | * | * | * | * | * | * |
| 11−1 | 1830 | 160 | 65 | 41% | 95 | 59% | 91% | 82% | 1,8% | 1,9% | 2,1% | 95% | 90% | 1,1% | 1,1% | 1,0% |
| Total | 59722 | 9253 | 2356 | 6897 | ||||||||||||
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