Evaluation of Restorative Procedures in Children following Dental Rehabilitation under General Anesthesia Omar A.S El Meligy*, Niveen S. Bakry**, Maha M.A. El Tantawi*** Abstract: The present study was carried out to assess the success of oral rehabilitation performed under general anesthesia (GA) in the "Special Care Unit", in the Department of Pediatric and Community Dentistry, Faculty of Dentistry, Alexandria University, in terms of restoration survival and absence of new/recurrent caries. The study involved 93 healthy patients who had previously received oral rehabilitation under GA in 2002-2003 and who were recalled for follow up examinations after a time period ranging from 20-42 months. The mean age of the children was 3.79 ± 1.23 years. Data were collected from the children and their families through clinical examination to assess the success of the restorations previously inserted under GA and the presence of new caries. Background information about the education and occupation of parents as well as dietary and oral hygiene habits and visits to dentists were also collected through a questionnaire. Kaplan Meier survival analysis was performed to determine the mean survival time in months of the different restorations. Cox regression model was used to examine the effect of different variables on the time to restoration failure. Logistic regression was used to study the effect of different variables on presence of new caries in different surfaces. The failure rate for anterior restorations was 49.3% and 12.7% for posterior restorations with a total number of restorations failing = 207 out of 746 initially inserted. The longest and shortest survival times were for strip crowns and anterior glass ionomer for anterior restorations (38 and 32 months respectively) and for posterior restorations stainless steel crowns and amalgam (40 and 36 months respectively). Not visiting the dentist increased the hazards of failure of both anterior and posterior restorations (hazards * ** *** Lecturers in Pediatric Dentistry, Faculty of Dentistry, Alexandria University Lecturer in Dental Public Health, Faculty of Dentistry, Alexandria University 1 ratio = 1.54 and 1.89 respectively). Out of 42 subjects who had new caries lesions, 29 had proximal lesions with a total number of new caries lesions on any surface = 53. Not eating snacks significantly lowered the risk of new caries on any surface (odds ratio= 0.05, CI= 0.01, 0.19). Strip crown and stainless steel crown had the longest survival times among anterior and posterior restorations. In spite of the radical treatment delivered to these children, they will need further treatment mostly to replace failed restorations. Introduction: Treatment under general anesthesia (GA) is an important modality for managing young children in need of comprehensive restorative and surgical dental treatment. These patients may need GA either due to their young age, limited ability to cooperate in a normal dental setting, having special needs or due to extensive treatment required (1). It has the advantage of permitting treatment in a single visit, allowing immediate relief of pain and requiring little or no cooperation from the child (2-4). In addition, it is supposed to provide the operator with the ideal working environment during delivery of treatment which can lead to improved success rates for treatment. At the same time, treatment under GA imposes on the operator the selection of radical treatment choices to avoid the need for replacement of failed restorations. Other problems associated with dental rehabilitation under GA is the high cost (5), small but significant risk of mortality (6,7) and the risk of new and recurrent caries due to the initial high level of decay (1). Furthermore, evidence suggests that restorations have a limited life span and that once a tooth is restored, the filling is likely to be replaced many times producing what is known as the “restorative cycle” (8). For treatment provided on the dental chair, it is estimated that about 60% of all restorative work is concerned with replacing existing restorations (9). In addition, children who receive oral rehabilitation under GA are 2 particularly susceptible to future high caries increment because they are high caries risk by definition since their caries level is high and their dietary and oral hygiene habits are unsatisfactory. All these problems necessitate the objective evaluation of the process of oral rehabilitation under GA to determine if the dentition restored to function under GA remains in a functional and painless condition following such massive intervention. Moreover, there is a need to examine both technical factors such as material and technique used in addition to parent and patient factors which are known to affect restoration longevity but have generally been less studied (10). Such factors include oral hygiene and dietary habits, visits to dentist, patient's age and gender. Therefore, this study was carried out to assess the success of oral rehabilitation performed under GA in the "Special Care Unit" in the Department of Pediatric and Community Dentistry, Faculty of Dentistry, Alexandria University, in terms of restoration success and absence of new caries. Parent characteristics and patient attitude was also analyzed to identify children at risk for repeated sessions of dental treatment. Materials and Methods: The present study was based on dental records of healthy patients who had undergone comprehensive dental treatment under general anesthesia in the "Special Care Unit", in the Pediatric and Community Dentistry Department, Faculty of Dentistry, Alexandria University. Healthy children included were defined according to Sheller et al (11) as those patients classified by attending anesthesiologist as ASA I or II at time of surgery and having no developmental delays or disabilities. There were 32 patients' 3 records for operations performed in 2002 and 61 for patients receiving treatment in 2003. Patients whose records were available were recalled for follow up in July- August 2005 and examined by a single examiner. Recalled patients were provided with topical fluoride gel application and oral hygiene instructions and referred to treatment if needed. Collected data included date when oral rehabilitation was performed under GA, patient's age at GA, number of sound, decayed and extracted teeth present at GA, as well as details about the tooth and surface affected. In addition, patient's records included also information about type of restoration inserted. At the follow up visit, the purpose of the study was explained to the parent/s and consent for participation in the study was obtained. Parents were given a questionnaire to fill in and- if needed- help was provided to them to fill it. This questionnaire collected information about the education and job of both father and mother. In addition, there were questions investigating the child's oral hygiene habits (frequency and if it was supervised by parent or not) and dietary habits (if the child snacked in between meals) in addition to frequency of visits to the dentist after GA rehabilitation. The child was examined to determine the fate of restorations previously inserted under GA. Restoration failure was considered to occur if a restoration needed replacement due to structural breakdown (fracture or dislodgement of the restoration), if there was pulpal or dentoalveolar infection associated with the restored tooth or if there was recurrent decay. Lost stainless steel crown was considered to be a failure. Intact restorations without new caries at the time of follow up were considered to be successful. Intra oral examination at follow up also checked for new carious lesions. Bitewing radiographs were used to diagnose proximal caries. New carious lesions were recorded 4 clinically on smooth surfaces and pits and fissures. The behavior of the child at follow up examination was rated according to Corah's Dental anxiety Scale (12). Statistical analysis consisted of descriptive statistics for the study sample characteristics and the status of teeth (decayed, extracted or filled). Analytical statistics comprised Kaplan Meier survival analysis performed to determine the mean survival time in months of the restoration types under study (13). Tarone Ware test for comparing the equality of survival distributions was used. In this test, time points are weighted by the square root of the number of cases at risk at each time point. Pairwise comparisons between different restorations types was done for two separate strata: anterior and posterior restorations separately. Cox regression model was used to examine the effect of different variables on time to restoration failure. Backward stepwise selection method was used for variables selection into model. Logistic regression analysis was used to determine the predictors of new caries lesions in any surface, in pits and fissures and in proximal surfaces. Bar graph was used to display the mean number of decayed surfaces totally and by surface affected. Results: The study included 93 patients, 32 of whom had been treated under GA in 2002 (mean age=4.21 ± 1.22), and the remaining 61 in 2003 (mean age= 3.57 ± 1.11). The interval between the time when the first operation was performed under GA and the time when children were examined at follow up ranged from 20- 42 months. Table 1 shows the sociodemographic, oral hygiene, dietary habits and dental visiting of the study sample. The majority of children in the study had mothers who were 5 housewives (66.7%) and who had secondary school level or higher education (68.8%), had fathers who worked as skilled workers (75.3%) and had secondary school level or higher education (78.5%). The majority of children exhibited good behavior during examination at follow up (76.3%) reported brushing frequently (71%) and that this brushing was under supervision (52.7%). They also reported visiting the dentist regularly (57%) and eating snacks (58.1%). Table 1: Sociodemographic, oral hygiene, dietary habits and dental visits of the study sample Variables Categories Frequency Percent Occupation of mother Housewife 62 66.7 Professional 10 10.8 Skilled worker 21 22.6 Professional 23 24.8 Skilled worker 70 75.3 Secondary / diploma or more 64 68.8 Primary 29 31.2 Secondary / diploma or more 73 78.5 Primary 20 21.5 Good 71 76.3 Bad 22 23.7 Frequent 66 71 Not frequent 27 29 49 52.7 Occupation of father Education of mother Education of father Behavior in clinic Brushing frequency Supervision of Yes brushing No 44 47.3 Visits to dentists Yes 53 57 No 40 43 Yes 54 58.1 No 39 41.9 Eating snacks 6 Table 2 shows the number of restorations inserted, percent failed, percent survived as well as the mean survival time in months. Among the different types of anterior restorations inserted, the longest survival rates was for strip crown followed by composite and lastly anterior glass ionomer (survival rates= 64.5%, 47% and 43.8 respectively). No statistically significant differences existed between the mean survival time of composite (33 months) and that of anterior glass ionomer (32 months) (p value >0.5). However, the difference between the mean survival time of strip crown (38 months) and both composite and glass ionomer was statistically significant (p<0.05). Among the posterior restorations inserted the longest survival rates were for stainless steel crown, posterior glass ionomer and then lastly amalgam restorations (91.7%, 81.4% and 76.5% respectively). For posterior restorations, there was a statistically significant difference between the mean survival time of stainless steel crowns (40 months) and both posterior glass ionomer (39 months) and amalgam (36 months) (p<0.05) but not between amalgam and posterior glass ionomer (p>0.05). The difference between the survival times of anterior and posterior restorations was also statistically significant (p<0.05). Figures 1 and 2 show the cumulative survival functions plots of anterior and posterior restorations in the study. 7 Table 2: Number of restorations inserted, percent failed, percent survived and mean survival time in months Anterior Type of restoration Inserted: Failed: / N (% of N posterior total) (% Survived: Mean of N (% of survival inserted) inserted) time in months (95% CI)* Anterior Strip crown 76 (24.8) 27 (35.5) 49 (64.5) 38 (37, 40) Composite 166 (54.2) 88 (53) 78 (47) 33 (32, 34) 36 (56.2) 28 (43.8) 32 (29, 34) 151 (49.3) 155 (50.7) 34 (33, 35) steel 289 (65.7) 24 (8.3) 265 (91.7) 40 (39, 41) glass 70 (15.9) 13 (18.6) 57 (81.4) 39 (37, 41) Amalgam 81 (18.4) 19 (23.5) 62 (76.5) 36 (34, 37) Total 440 56 (12.7) 384 (87.3) 39 (38, 40) 746 207 (27.7) 539 (72.3) 37 (36, 37) Anterior glass 64 (20.9) ionomer Total Posterior Stainless 306 crown Posterior ionomer Total anterior and posterior * CI: confidence interval 8 Figure 1: Cumulative survival plot of anterior restorations Survival Functions for posterior restorations 1.0 amalgam stainless steel crown posterior glass ionomer censored amalgam censored st st crown censored posterior glass ionomer Cum Survival 0.8 0.6 0.4 0.2 0.0 20 25 30 35 40 45 time in months Figure 2: Cumulative survival plot of posterior restorations 9 Table 3 shows the factors significantly affecting time to failure of anterior and posterior restorations. Strip crown had one third the hazards ratio of failure compared to other anterior restorations (HR=0.33, CI= 0.20, 0.55). Absence of new caries decreased the hazards ratio of anterior restorations (HR= 0.49, CI= 0.33, 0.73). Not visiting the dentist regularly increased the hazards ratio for both anterior and posterior restorations (HR = 1.54 and 1.89, CI = 1.05, 2.26 and 1.08, 3.32 respectively). Not eating snacks decreased the hazards ratio of posterior restoration (HR= 0.42, CI= 0.21, 0.83). Table 3: Factors significantly affecting failure of restorations (Cox proportional hazards model) Anterior / Variables posterior Wald chi P value HR 95% CI <0.0001* 0.33 0.20, 0.55 <0.0001* 0.49 0.33, 0.73 0.03* 1.54 1.05, 2.26 0.03* 1.89 1.08, 3.32 0.02* 0.42 0.21, 0.83 square Anterior Using strip crown 18.2 restoration Not having new 12.45 caries Not visiting the 4.93 dentist Posterior Not visiting the 4.90 restorations dentist Not eating snacks 6.18 HR= hazards ratio, CI= confidence interval *= Statistically significant at p ≤ 0.05 Table 4 shows the number of new caries, fillings and extraction in the study sample. The majority of new caries occurred in proximal surfaces (mean ± SD= 0.31 ± 0.47, percent of subjects= 31.2%, percent of total surfaces = 1.66%). Almost half of the patients recalled for follow up (42 patients forming 45.2% of the study sample) were 10 found to have new caries lesions. There were 53 new caries lesions (3.03% of all teeth in the study). Figure 3 shows the mean number of teeth with new caries in all surfaces, in pits and fissures, in proximal surfaces and in smooth surfaces. Table 4: New carious lesions, previous fillings and missing teeth in study sample Min Max Mean ± SD Subjects with Surfaces with condition: condition: N (%) N (%) New pit and fissure caries 0 2 0.24 ± 0.52 18 (19.4) 22 (1.26) New proximal caries 0 1 0.31 ± 0.47 29 (31.2) 29 (1.66) New smooth caries 0 1 0.02 ± 0.15 2 (2.2) 2 (0.11) New total caries 0 3 0.57 ± 0.71 42 (45.2) 53 (3.03) Missing 0 10 0.96 ± 1.85 32 (34.4) 110 (6.3) Filled 2 18 8.25 ± 3.55 93 (100) 746 (42.7) DMF 3 28 9.77 ± 4.16 93 (100) 909 (52.03) Sound 1 17 10.3 ± 3.93 93 (100) 838 (47.97) All surfaces 14 20 19.85 ± 0.74 - 1747 (100) 11 0.6 Mean number of teeth 0.5 0.4 0.3 0.2 0.1 0 total new caries new pit and fissure caries new proximal caries new smooth caries Figure 3: Mean number of teeth with new caries in different sites Table 5 shows the factors significantly affecting the occurrence of new caries lesions. Because there were only two new smooth surface lesions, they were not included in the logistic regression analysis. For caries in pits and fissures, in proximal surfaces or in any surface, not eating snacks significantly reduced the risk of new caries (OR= 0.03, CI= 0.003, 0.38, OR= 0.16, CI= 0.05, 0.54 and OR= 0.05, CI= 0.01, 0.19 respectively). 12 Table 5: Factors significantly affecting occurrence of new lesions (logistic regression model): Caries Predictor Wald chi P value OR CI square Pit and fissure caries Not eating snacks 7.58 0.006* 0.03 0.003, 0.38 Proximal caries Not eating snacks 8.64 0.003* 0.16 0.05, 0.54 Any caries Not eating snacks 17.94 <0.0001* 0.05 0.01, 0.19 OR= odds ratio, CI= confidence interval, *= Statistically significant at p ≤ 0.05 Discussion: The study involved data from records and clinical examinations of 93 healthy patients receiving oral rehabilitation under GA. Almost one third of these patients (29%) did not brush regularly and 43% of them did not visit a dentist regularly for check ups after GA. The majority (58.1%) still had snacks between meals. In view of the radical treatment these children had undergone under GA and the cost involved, their dietary and oral hygiene habits were expected to be better, but it seems that dental treatment under GA has little effect on promoting oral health by itself (14). Oral health education and prevention should closely follow GA to educate the patient and ensure an environment promoting restoration success. Failed anterior and posterior restorations formed 27.7% of all restorations previously inserted under GA. Several studies have shown that the percentage of failed restorations in primary teeth is in the range 20-30% (15, 16). Posterior restorations generally survived longer than anterior restorations with nearly half (49.3%) of the latter failing after three and half years of insertion. Composite was the most frequently inserted 13 anterior restoration, but nearly half of these restorations failed. Sheller et al (11) reported a similar failure rate (55%) of multisurface composite restorations in patients who required another GA session for dental treatment. Strip crown is the first choice of many clinicians due to superior esthetics and ease of repair if the crown should subsequently chip or fracture. The success rate of composite strip crown in the present study was 64.5% which is similar or somewhat higher to the 49% success rate reported by Tate et al (17). GA allows treatment to be done under good condition of isolation which enhances composite retention. However, the rate of success of composite restorations was 47%. Composite was used to restore class III and class V. it would appear that when removing interproximal or cervical decay on primary incisors, keeping a very small conservative preparation may not be the best choice. Pulp chamber of primary incisors is comparatively large and the enamel and dentin are thin. Consequently the depth of cavity preparation becomes very shallow, which may result in insufficient amount of restorative material, predisposing to loss of restoration (18). Therefore, it has been recommended that even small class III in primary teeth should have a labial or lingual dove tail or should incorporate a large surfaces area for bonding to enhance retention (19). The success rate of glass ionomer restorations was 43.8%. These results were comparable to the results of Basso and Edelberg (20) and Lo and Holmgren (21) who evaluated long term success of glass ionomer cement placed into class III preparation which ranged from 20-73% after one year and only 14% after 30 months respectively. Glass ionomer cements are useful in situations where economics or access to care is a significant problem but they can not deliver predictable and esthetic restoration of primary incisors. 14 Distribution of posterior restorations indicates that clinicians in the Special Care Unit favor maximum coverage using stainless steel crown since stainless steel crowns were the most frequently inserted posterior restoration and it seems that their choice was justified since it was the most successful among all posterior restorations. Sheller et al (11) also reported that stainless steel crowns had the highest success rates (93% for stainless steel crowns alone and 83% for stainless steel crowns with pulp treatment) in children who needed another GA session for dental treatment. Tate et al (17) reported an almost identical small failure rate (8%) for stainless steel crown inserted under GA after a follow up period ranging from 3 to 11 years. Studies evaluating the success and longevity of different restorations in a routine dental setting support the superiority of stainless steel crowns (22). Similar results were also concluded from studies of outcomes of restorations placed under GA (23). The choice of material for posterior restorations indicates a move towards posterior glass ionomer which in the present study was almost equal to the number of inserted amalgam restorations. The same situation is starting to show in different areas of the world, especially in Scandinavia and Germany (24). Part of the reason for this phenomenon may be due to the potential cariostatic effect of glass ionomer cements owing to the release of fluoride. However, no such effect has been shown in comparative studies of amalgam and glass ionomers (24), or in the present study. Similar to the present study, Mjor et al (24) in a practice based study found that the median age of replaced amalgam in children was 3 years, but their study found that the mean age of amalgam was significantly higher than that of glass ionomer restorations which is contrary to our findings. This could be explained by the fact that in the present study, posterior glass ionomer was used for simple class I cavities which may have 15 increased its success rate compared to amalgam which was used in more extensive cases. A review by Hickel et al (25) found that the failure rate of posterior restorations ranged from 0-14%, for stainless steel crown and 0-35.3% for amalgam which is in accordance with our results. Restoration failure was affected by some technical factors such as choice of restoration; so that using strip crown significantly reduced the hazards of failure in anterior teeth. Other behavioral factors had significant effect on failure; so that not visiting the dentist increased the hazards of failure for both anterior and posterior restorations while avoiding snacks reduced the hazards of posterior restoration failure. Absence of caries reduced the hazards of anterior restoration failure. Mjor et al (24) found that the main reason for replacement of restorations in primary teeth was caries (ranging from 48% in conventional glass ionomer to 53% in amalgam) followed by fracture of restorations. Similarly, several studies confirm that diagnosis of caries is the most common reason for the replacement of restorations (10). Almeida et al (26) compared new caries lesions in patients with early childhood caries (ECC) and controls who were initially caries free. Both groups were followed up for more than two years. New pit and fissure caries occurred in 26% of the controls compared to 40% of cases with ECC, while new smooth surface caries occurred in 13% of controls compared to 60% of cases. The prevalence of new pit and fissure caries in the present study is thus considered comparatively lower than that reported in their study, while the prevalence of new smooth caries is similar to that reported in their study. The one factor significantly affecting absence of new caries lesions in any surface in the present study was avoiding snacks. 16 Appreciation of the multifactorial nature of dental caries is important when developing a treatment plan. Child, parent and dentist all influence the outcomes of treatment. A child will not voluntarily alter his/her diet or improve his/ her oral hygiene habits. The responsibility for these changes rest with the care giver. 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