Early prognostic indicators and outcome prediction model for replanted avulsed teeth.
AIM: To identify early clinical variables that are most predictive
of treatment outcome and to develop a model that will allow prediction
of treatment outcomes based on these variables. STUDY DESIGN AND
METHODS: A dental trauma database was used to randomly identify patients
who had received treatment for avulsed teeth between 1998 and 2007. A
data extraction form was designed and completed for each tooth.
Demographic, diagnostic and treatment information recorded in the
patient's records, in addition to radiographs, were viewed
retrospectively. STATISTICS: The significance and the predictive power
for each early clinical variable were assessed using a univariate
logistic regression model. Only significant variables (p [less than or
equal to] 0.05) were considered eligible for the prediction model and a
c-index was then constructed for their respective predictive power (0.5
= no predictive power, 1.0 = perfect prediction). RESULTS: Of the
original sample of 213 patients who had received treatment for avulsed
teeth between 1998-2007 only 105 fulfilled the criteria for evaluation.
Two models ('At first visit' and 'at initial treatment
visits') were produced with a total of five variables that were
significant and holding the greatest predictive power (high c-index):
patient age (p=0.001, c=0.80); stage of root formation (p=0.001,
c=0.76); storage medium (p=0.047, c=0.58); tooth mobility after dressing
(p=0.001, c=0.70); and tooth mobility after splinting (p=0.003, c=0.70).
These variables underwent multi-variate analysis and the final models
had good predictive abilities (c-index of 0.80 and 0.74). CONCLUSION:
These predictive models based on patient age, stage of root formation,
storage medium, tooth mobility after dressing and tooth mobility after
splinting were shown to have high predictive value and will enable a
clinician to estimate the long term prognosis of avulsed and replanted
teeth. It will enable planning for further treatment with a realistic
view of outcome at an early stage.
Key words: Dental avulsion, prediction, outcome
Avulsion fractures (Care and treatment)
Tooth fractures (Diagnosis)
Tooth fractures (Care and treatment)
Oral surgery (Patient outcomes)
Teeth (Physiological aspects)
|Publication:||Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 European Academy of Paediatric Dentistry ISSN: 1818-6300|
|Issue:||Date: August, 2012 Source Volume: 13 Source Issue: 4|
|Geographic:||Geographic Scope: United Kingdom Geographic Code: 4EUUK United Kingdom|
Dental avulsion injuries are distressing and when they occur can affect the daily life of both patients and their parents. Answers to a question from parents and patients about the prognosis for avulsed and replanted teeth remain unclear. Outcome prediction is useful for clinical decision making, family counseling, evaluation of quality of treatment, and medical resource allocation. Many variables and factors have been suggested in the literature that might affect the treatment outcome of these injuries [Cvek et al., 1990; Mackie and Worthington, 1992; Trope, 2002; Pohl et al., 2005a and 2005b], and many attempts have been conducted to study these variables [Andreasen, 1975; 1981; Weinstein et al., 1981; Al-Nazhan et al., 1995; Boyd et al., 2000; Kinirons et al., 2000; Andreasen et al., 2002, 2004; Cardoso et al., 2008; Stewart et al., 2008; Tzigkounakis et al., 2008; Hinckfuss and Messer, 2009; Petrovic et al., 2010]. Prior avulsion studies have presented survival analysis [Barrett and Kenny 1997; Pohl et al., 2005b; Petrovic et al., 2010] however, a mathematical model to estimate the long term prognosis of these injuries has not yet been established. The aim of this study was to: identify and to determine the early clinical variables (indicators) that were most predictive of treatment outcome and to develop a model(s) that would predict the outcome for replanted avulsed teeth based on these early clinical variables.
Material and methods
The study consisted of two parts. The first part was a review of patients' records gathering the target data together with assessment of each radiograph taken throughout the follow-up period. The second part was a review of all early related variables. These were subsequently added together to develop a model(s) that would predict the outcomes for replanted avulsed teeth based on early clinical variables. The outcome in all cases was assessed retrospectively and were categorised into two groups either failure or continued function based on the findings of the clinical and radiographic evaluation after at least one year of follow-up. The criteria in Table 1 are based upon every clinician's, 'goal'; namely to retain an avulsed and reimplanted tooth in the mouth functioning for as long as possible and if possible until full growth is achieved. Maintaining the tooth and its surrounding bone for a few years can be considered a successful treatment in the growing patient [McIntyre et al., 2007; Trope, 2011].
The study sample. The study population comprised patients treated within the Paediatric Department of Glasgow Dental Hospital and School, who had sustained traumatic injuries leading to avulsion of anterior permanent tooth/teeth. The department trauma database was used to identify all patients who had received treatment for dental avulsion in the period 1998-2007. For each patient only one avulsed tooth was randomly selected to be recruited in the study. For inclusion in the study teeth had to have been followed for more than one year after avulsion and replantation or until failure. Teeth were excluded from the study if: they had not been replanted; were lost to follow-up; had been followed for less than a year; had sustained a root or crown fracture; had been autotransplanted; or had sustained subsequent trauma after replantation.
Data elements. Diagnostic and treatment information recorded in each patient's records and on the formatted structured history trauma sheet in the records, in addition to radiographs, were the source of the data for this study. In order to aggregate all the target information from the patients' records, an extraction data form was designed to include all the early clinical variables including the patient's demographics. For each tooth, an extraction data form was completed and given a unique ID number and coded for computer entry. Confidentiality of patient information was considered throughout the study, as each patient's name and contact details were kept concealed. The data was retrieved by one of the authors (OR) and randomly reviewed by a senior consultant under standardised conditions.
Radiographic evaluation. Each tooth was evaluated for the presence of any radiographically detectible pathological changes including root resorption on a standard viewing box. Subsequently, each set of radiographs for each patient was analysed according to the chronological order of the visits until the pathological changes were detected. After determining the type and progress of root resorption, each radiograph was analysed till the tooth had either been retained or lost.
With regard to validity and reproducibility assessment for data extraction and to check for bias in data recorded in this study, a sample from the records was reviewed randomly by a senior consultant under standardised conditions. Consensus agreement was reached for the collection of the data and the clinical and radiographic outcomes.
Statistical methods. SPSS statistical software program 15.0 Standard version was adopted for use in data analysis. The data were subsequently coded, entered, processed and then analysed. Each variable in the study was examined initially by frequency tabulation. The variables were pooled into categories that represented natural grouping, whilst attempting to retain reasonable numbers of subjects in each category. The results for each variable were then expressed in the form of Pearson's Chi-square ([chi square]) test and odds ratios (OR) with 95% confidence intervals. In order to assess the individual significance for each variable a univariate logistic regression model was employed. Only those variables that were significant at the 5% level were considered for further assessment. For each variable the predictive ability was assessed using c-index. The c-index is equal to the area under the receiver operating characteristic (ROC) curve, which is commonly used as a summary index of the model performance [Harrell et al., 1984 and 1996]. Generally the area under the curve ranges from 0.5 to 1.0 and provides a measure of the model's ability to discriminate between those subjects who experience the outcome of interest versus those who do not [Altman and Bland, 1994; Hosmer et al., 2000]. A variable with no predictive power (no discrimination) has a c-index of 0.5 and a variable with perfect predictive power (excellent discrimination) has a c-index of 1.
Those variables that were identified as significant in this analysis were then analysed once more using forward stepwise logistic regression to produce a parsimonious model that can predict treatment outcome. Given the nature and specificity of this type of trauma and its treatment these variables were pooled together to form two groups based on the consequences of the variable in the process (variables at 'first visit' or at 'initial treatment visits'). Therefore two models were produced that could predict the treatment outcome: Model 1- 'At first visit'; Model 2- 'at initial treatment visits'. All cases were included in this analysis apart from those subjects omitted because of a missing subject data point, regardless of the availability of the others.
A total of 213 patients' records were studied. Of these 108 were excluded at the beginning of the study in accord with the exclusion criteria. There were 105 avulsed permanent teeth in 105 patients subsequently recruited. All patients were regular attenders in the period 1998-2007 with 60 male patients (57%) and 45 female patients (43%). The mean of patients ages at time of trauma was 10 years (SD [+ or -] 2.61 yrs), with a range of between 6-16 years. The trauma was most frequent in age group 6-9 years of age.
The most commonly traumatised teeth were the maxillary right and left central incisors (65 teeth, 62% and 31 teeth, 30% respectively). Falls and sporting accidents were the most common causes of trauma (42 teeth, 40% and 47 teeth, 45% correspondingly). Most of the injuries occurred in outdoor locations (67 teeth, 64%), while the second most frequent location was at school (19 teeth, 18%). Some patients sustained a complicated trauma comprising avulsion with enamel dentine fracture or with pulp exposure, while the majority (88 teeth, 84%) was avulsion only. In 42 patients (40%) had avulsed two or more teeth at the same occasion. There were no decoronation cases in the sample.
[FIGURE 1 OMITTED]
The mean follow-up period for the 105 teeth was about 4 years (SD [+ or -] 2.16yrs), ranging between 0.19 (failed) and 10.82 years. The mean number of attendances (visits) was 24 with a maximum of 60. Extra alveolar dry time (EADT) ranged between 0-420 min with a mean of 41 min. EADT was less than 60 min for 71 cases (68%).
The storage medium was varied. The majority of the cases (73 teeth, 70%) were stored in milk, whilst the remainder were stored either dry or in other media. For 48 teeth (46%) there were completely formed apices, 38 teeth (36%) had nearly completed roots and the remainder (19 teeth, 18%) were immature rooted teeth at the time of their presentation. The most common type of splint was composite/wire (73 teeth, 70%). In all, the fixation period for about 43 teeth (46%) of the cases was less than 10 days and 11-15 days for about 22 teeth (23%) of the cases. Mobility after splinting was recorded in 58 teeth.
Pulps were removed within 15 days in 48 teeth (46%) and only 4 teeth did not require pulpal removal as they revascularised. Non-setting calcium hydroxide (NS-Ca[(OH).sub.2]) was the most popular initial intra-canal dressing used (85%) compared with only 15% of cases with Ledermix. Mobility after commencement of root canal dressing was documented in 53 teeth (51%). The frequency and the number of times the root canal dressing were changed depended on both the stage of root formation and the dryness of the root canal.
Teeth with incompletely developed roots and teeth with canals which failed to dry required longer total durations of intra-canal dressings and more changes of dressings. Root resorption was observed in 81 cases (77%) and in more than 58 cases (55%) this was inflammatory root resorption. Replacement root resorption was observed in only 23 cases (22%). Based on the study assessment criteria (Table 1), the failure rate was 36 cases (34%), while continued function was recorded in 69 cases (66%).
Significance of study variables. The significance of all the variables in terms of p value and their predictive ability in terms of c-index are summarised in Table 2 in descending order of statistical significance.
Model production. The significant variables were selected for further analysis to produce an appropriate model for predicting outcome. Overall 82 of 105 teeth were entered into the final stage of analysis (model production process). There were 23 teeth omitted from the analysis because of missing data points in certain variables regardless of the availability of the others.
Model 1: At first visit. This model enables prediction of the outcome at the first day of trauma. Combinations of significant variables were selected and entered into the model (patient age 'age group', storage medium and stage of root formation). These three variables were entered together into one model (Table 3) which showed a good predictive ability (c-index of 0.80, Figure 1). The overall accuracy of the model to predict failure of the treatment was 77%. In summary the major factors influencing the outcome (treatment failure) at this stage of 'first visit' after dental avulsion and replantation would appear to be: younger age; dry storage medium; and immature roots.
Model 2: At initial treatment visits. This model enables prediction of long term outcome from early clinical information collected from 10-45 days after trauma. Combinations of significant variables were selected and entered into this model (tooth mobility after dressing and tooth mobility after splinting). These two variables were entered together into the model (Table 3) and showed good predictive ability (c-index of 0.74, Figure 1). The overall accuracy of the model to predict failure of treatment was 72%. In summary the major factors influencing the outcome (treatment failure) at this stage of 'initial treatment visits' after dental avulsion and replantation appear to be the recording of tooth mobility, either after splinting or after starting root canal dressing.
The main observations arising from this study were the magnitude of risk that dry storage medium, immature roots and a younger age exerts on the outcome (treatment failure) at an early stage after dental avulsion and replantation (at 'first visit after trauma'). This is the first study to have looked at the effects of clinical variables on the outcome of avulsed and replanted teeth and to have developed models to predict treatment outcome. Two models were produced from the five variables holding the greatest predictive power (c-index), which underwent multivariate analysis. The final models were developed with good predictive abilities 'c-index' of 0.80 and 0.74 (c-index of 1.0 being perfect prediction), with an overall prediction accuracy of 77% and 72% correspondingly. These levels of prediction abilities and prediction accuracy validate the models and hence their abilities to predict treatment outcome (treatment failure).
The study was designed to pool some of the advantages of previous prospective and retrospective studies. Objective diagnostic information was consistently accessible from patient records and was not subject to a recall bias (reporting bias). Special data extraction sheets were created retrospectively from existing patients records and study subjects were traced until discharge to ascertain whether their tooth was still functioning or whether it had failed based on the criteria in Table 1. Teeth diagnosed as having failed were compared against teeth that were still functioning. The purpose was to determine whether the two groups differed in the proportion of teeth exposed to risk factors.
There is a concern about the bias caused by having the same researcher (one of the authors) performing the analysis and assessment. However the dentist abstracting the records and performing the analysis and assessment was not the treating dentist. The patient's record was reviewed and analysed in entirety according to the chronological order of the visits until the pathological changes were detected. After determining the type and progress of pathological changes, each radiograph was analysed till the tooth had either been retained or extracted. This systematic evaluation, according to the study protocol, ensured consistency of evaluation and eliminated the problem of inter-observer variability. Subsequently, the comparison between the radiographs was made by the main researcher and a random sample of radiographs was independently reviewed by a senior consultant under identical standardised conditions. The findings were compared, and the outcome was assessed, and a final consensus agreement was reached.
This study recruited any anterior permanent tooth sustaining traumatic injuries leading to avulsion. Although these teeth had been treated under three different treatment protocols (BSPD1998 [Gregg and Boyd, 1998]; IADT 2001 [Flores et al., 2001]; IADT 2007 [Flores et al., 2007]), the comparison of outcome rates using these three protocols did not show any significant difference. Nevertheless any avulsed teeth that were lost at the time of the accident, had a short follow-up period, were lost to follow-up, had root fractures, had been autotransplanted, or had sustained subsequent trauma after replantation were all excluded from the study. Although this may have resulted in loss of some power in evaluating coefficients for the logistic regression models, the sample sizes were sufficient to fit valid models.
Post-operative outcomes. Pohl et al. [2005a] based their results on the post-operative healing classified as: functional healing; replacement resorption; and infection-related (inflammatory) resorption. Petrovic et al.  similarly classified post-operative outcomes according to the root resorption). Soares et al.  relied on clinical and radiographic post-operative outcomes as complete success, acceptable success, uncertain success, or failure. During this present study, the clinical diagnosis was based upon whether the tooth pulp and the root had any pathological changes and/or periapical involvement. A tooth/root that was retained and continued functioning, in absence of an abscess or sinus tract of pulpal or endodontic origin, but ultimately planned for extraction (because of root resorption) when patient was in their late teenage years was classified as continuing in function. This agrees with McIntyre's and Trope's definition of success, that maintaining the avulsed and replanted tooth and its surrounding bone for a few years can be considered a successful treatment in the growing patient [McIntyre et al., 2007; Trope, 2011]. This may effectively minimise a positive association between a risk factor and outcome.
Odds ratios (OR) were calculated for all clinical diagnostic variables. Some of the variables showing no association appeared statistically significant such as extra-alveolar dry time, EADT. This is probably due to the effect of the classification system criteria or sample size and identifies the need for further studies to support the results. In the overall data analysis, (EADT) was not a factor associated with the outcomes of the treatment (n=82, p=0.102). However it is an important observation that the majority of successful cases had a short EADT. Given the nature and specificity of this type of trauma and its treatment these variables were pooled together to form two groups based on the clinical consequences. Only variables that were identified as the strongest predictors of outcome at an early stage after avulsion were considered in the first logistic regression model (at first visit) e.g. dry storage medium, immature roots and younger age. In the same way, variables that were identified as the strongest predictors of outcome at the initial treatment visits (10-45 days after replantation) were involved in a second logistic regression model, e.g. tooth mobility, either after splinting or after starting root canal dressing. In this study, recording of tooth mobility greatly reduced a favourable prognosis.
These predictive models based on patient age, stage of root formation, storage medium, tooth mobility after dressing and tooth mobility after splinting were shown to have high predictive value and will enable clinicians to estimate the long term prognosis of avulsed and replanted teeth. It will enable planning for further treatment with a realistic view of outcome at an early stage.
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O. Rhouma, A.D. McMahon, R.R. Welbury Department of Paediatric Dentistry, Glasgow Dental Hospital and School, Glasgow, Scotland.
Postal address: Dr O. Rhouma, Department of Paediatric Dentistry, Level 5, (Prof. Welbury office), Glasgow Dental Hospital and School, 378 Sauchiehall Street, Glasgow, G2 3JZ, United Kingdom.
Table 1. Criteria used to determine treatment outcome Continued function Failure 1. A tooth is still in the mouth 1. Tooth extracted before with normal tooth function. achieving full growth age. 2. A tooth is retained with no 2. Tooth is still in the mouth clinical signs of infection up to with presence of clinical signs the age of full growth. of infection and expected to be extracted before the age of full 3. Tooth extracted after achieved growth. full growth age and long term treatment (Implant/Prosthesis) already started. Table 2. Univariate analysis of prognostic variables Outcomes Continued Variable function (%) Failure (%) Age at trauma (age group) 6-9 yrs old 17 (41.5) 24 (58.5) 10-13 yrs old 28 (71.8) 11 (28.2) [greater than or equal to] 24 (96.0) 1 (4.0) 14 yrs old Stage of root formation Immature 9 (47.4) 10 (52.6) Nearly complete 18 (47.4) 20 (52.6) Complete 42 (87.5) 6 (12.5) Tooth mobility after dressing No 41 (83.7) 8 (16.3) Yes 24 (46.2) 28 (53.8) Tooth mobility after splinting No 32 (82.1) 7 (17.9) Yes 30 (51.7) 28 (48.3) Storage medium Milk 52 (71.2) 21 (28.8) Dry 6 (37.5) 10 (62.5) Others 11 (68.8) 5 (31.3) Number of injured teeth One 37 (58.7) 26 (41.3) Two or more 32 (76.2) 10 (23.8) EADT <5 min 19 (86.4) 3 (13.6) 5-15 min 7 (58.3) 5 (41.7) 16-30 min 15 (60.0) 10 (40.0) 31-60 min 7 (58.3) 5 (41.7) > 60 min 4 (36.4) 7 (63.6) Contamination Not cited 27 (75.0) 9 (25.0) Washed off 39 (60.0) 26 (40.0) Not completely clean 3 (75.0) 1 (25.0) Trauma location Outdoor 45 (67.2) 22 (32.8) School 14 (73.7) 5 (26.3) Others 10 (52.6) 9 (47.4) Time to pulp access 1-15 days 34 (70.8) 14 (29.2) 16-30 days 10 (55.6) 8 (44.4) >30 days 21 (60.0) 14 (40.0) Main cause of trauma Fall 29 (69.0) 13 (31.0) Sport Accident 28 (59.6 19 (40.4) Others 12 (75.0) 4 (25.0) Type of root dressing NS-Ca[(OH).sub.2] 54 (63.5) 31 (36.5) Ledermix then 11 (73.3) 4 (26.7) NS-Ca[(OH).sub.2] Type of root dressing Maxilla Rt central incisor 40 (61.5) 25 (38.5) Maxilla Lt central incisor 22 (71.0) 9 (29.0) Others 7 (77.8) 2 (22.2) Additional coronal trauma Avulsion only 59 (67.0) 29 (33.0) Avulsion + crown fracture 10 (58.8) 7 (41.2) Root canal after dressing Dry and clean 57 (65.5) 30 (34.5) Pus (or any sign of 8 (57.1) 6 (42.9) infection) Use of antibiotics No 32 (66.7) 16 (33.3) Yes 37 (64.9) 20 (35.1) Splinting time 0-10 days 28 (65.1) 15 (34.9) 11-15 days 15 (68.2) 7 (31.8) >16 days 18 (62.1) 11 (37.9) Variable OR (95% CI) p value c-index Age at trauma (age group) 0.001 0.80 6-9 yrs old 1 10-13 yrs old 0.28 (0.11 - 0.71) [greater than or equal to] 0.03 (0.01 - 0.24) 14 yrs old Stage of root formation 0.001 0.76 Immature 1 Nearly complete 1 (0.33 - 3.01) Complete 0.13 (0.04 - 0.45) Tooth mobility after 0.001 0.70 dressing No 1 Yes 5.98 (2.35 - 15.21) Tooth mobility after 0.003 0.70 splinting No 1 Yes 4.27 (1.62 - 11.22) Storage medium 0.047 0.58 Milk 1 Dry 4.13 (1.33 - 12.80) Others 1.13 (0.35 - 3.64) Number of injured teeth 0.068 0.58 One 1 Two or more 0.45 (0.19 - 1.06) EADT 0.102 0,67 <5 min 1 5-15 min 4.52 (0.85 - 24.11) 16-30 min 4.22 (0.98 - 18.13) 31-60 min 4.52 (0.85 - 24.11) > 60 min 11.10 (1.97 - 62.51) 0.296 0.52 Contamination Not cited 1 Washed off 2 (0.81 - 4. 93) Not completely clean 1 (0.92 - 10.87) Trauma location 0.368 0.54 Outdoor 1 School 0.73 (0.23 -2.29) Others 1.84 (0.65 - 5.18) 0.415 0.60 Time to pulp access 1-15 days 1 16-30 days 1.94 (0.64 - 5.95) >30 days 1.62 (0.65 - 4 .06) Main cause of trauma 0.452 0.54 Fall 1 Sport Accident 1.51 (0.63 - 3.64) Others 0.74 (0.20 - 2.75) Type of root dressing 0.466 0.51 NS-Ca[(OH).sub.2] 1 Ledermix then 0.63 (0.19 - 2.16) NS-Ca[(OH).sub.2] Type of root dressing 0.487 0.58 Maxilla Rt central incisor 1 Maxilla Lt central incisor 0.66 (0.26 - 1.65) Others 0.46 (0.09 - 2.34) Additional coronal trauma 0.515 0.51 Avulsion only 1 Avulsion + crown fracture 1.42 (0.49 - 4.12) Root canal after dressing 0.545 0.55 Dry and clean 1 Pus (or any sign of 1.43 (0.45 - 4.49) infection) 0.850 0.55 Use of antibiotics No 1 Yes 1.08 (.05 - 2.43) Splinting time 0.902 0.51 0-10 days 1 11-15 days 0.87 (0.29 - 2.60) >16 days 1.14 (0.43 - 3.03) Table 3. Variables in Model 1 and Model 2 Outcomes Continued Variable function (%) Failure (%) OR (95%CI) Age at trauma (age group) 6-9 yrs old 10 (32.3) 21 (67.7) 1 10-13 yrs old 22 (73.3) 8 (26.7) 0.17 (0.06 - 0.52) >14 yrs old 20 (95.2) 1 (4.8) 0.02 (0.00 - 0.20) Storage medium Milk 41 (69.5) 18 (30,5) 1 Dry 6 (37.5) 10 (62.5) 3.80 (1.20 - 12.04) Others 5 (71.4) 2 (28.6) 0.91 (0.16 - 5.14) Stage of root formation Immature 7 (41.2) 10 (58.8) 1 Nearly complete 12 (42.9) 16 (57.1) 0.93 (0.28 - 3.07) Complete 33 (89.2) 4 (10.8) 0.09 (0.02 - 0.35) Tooth mobility after splinting No 33 (82.5) 7 (17.5) 1 Yes 19 (45.2) 23 (54.8) 5.71 (2.06 - 15.78) Tooth mobility after dressing No 35 (85.4) 6 (14.6) 1 Yes 17 (41.5) 24 (58.5) 8.24 (2.84 - 23.91) Yes 37(64.9) 20(35.1) 1.08 (.05 - 2.43)
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