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Background: Paediatric‐preformed zirconia crowns have been associated with several issues, primarily their inability to be crimped and the need for extensive tooth preparation. Additionally, the capacity to adjust the size, shape, and fit of these crowns is very limited. Aim: To evaluate and compare the fracture strength of four different types of dental crowns intended for paediatric patients. Design: The fracture resistance of four types of paediatric crowns was evaluated using the universal testing machine; freshly extracted primary molars received one of the following: preformed zirconia crowns, custom‐made computer‐aided design and computer‐aided manufacturing (CAD–CAM) zirconia crowns, custom‐made CAD–CAM ceramic crowns, and custom‐made CAD–CAM hybrid composite crowns. Data were statistically compared using the Kruskal–Wallis test followed by the Bonferroni test, and the level of significance was set at 5%. Results: Results showed that there was a statistically significant difference among the four groups (p <.001). The highest value of fracture force was observed for the milled zirconia crown and the lowest for the prefabricated zirconia. Conclusion: The implementation of the CAD–CAM digital crown fabrication technique has the potential to address issues associated with preformed crowns in paediatric patients, particularly in terms of fracture resistance. [ABSTRACT FROM AUTHOR]

Background: The Hall Technique (HT) is now regarded as one of the biological management options for carious primary molars and has shown significant clinical success. Aim: To investigate the perception and the use of the HT among dentists engaging in paediatric dentistry in East China. Design: This was an electronic questionnaire‐based cross‐sectional study. A quick response code of the questionnaire via WeChat, a common communication tool in China, was sent to dentists in East China. Results: A total of 313 dentists participated in this study. Most surveyed clinicians had heard about the HT (n = 286, 91.4%). Of them, 40.2% (n = 115) reported having used the HT. Of 67 dentists working in private clinics, 34 (50.7%) had used the HT, whereas only 37% of dentists from public hospitals had used the HT. Of 115 dentists having used the HT, 91.3% (n = 105) would consider using the HT for Class II cavitated molars; 23.5% (n = 27) would consider using the HT for Class I cavitated molars. Most dentists who had not used the HT were concerned about complications such as pulp inflammation or necrosis after applying the HT. Conclusion: The HT is well known in East China; the lack of systematic training or courses, however, may decrease its utilization. [ABSTRACT FROM AUTHOR]

Background: Endodontic treatment of primary molars represents one of the challenges in pediatric dentistry. There is a lack of consensus in the literature about the endodontic techniques and filling paste for primary teeth with pulp necrosis. Aim: To compare the effectiveness of the LSTR technique (lesion sterilization and tissue repair) with CTZ paste (chloramphenicol, tetracycline, zinc oxide and eugenol) and pulpectomy with ZOE paste (zinc oxide and eugenol) in the treatment of primary molars with pulp necrosis. Design: Eighty‐eight primary molars with pulp necrosis from 70 children between the ages of 3 and 8 years were included. The teeth were randomized to the LSTR with CTZ paste group or pulpectomy with ZOE paste group. Clinical and radiographic evaluations were performed at 18, 24, 30 and 36 months. Results: At 36 months, clinical success was 86.4% in LSTR with CTZ paste and 90.9% in pulpectomy with ZOE paste (p =.45). Radiographic success was 43.2% in both groups (p = 1.00). The overall success was 40.9% in LSTR with CTZ paste and 43.2% in pulpectomy with ZOE paste (p = 1.00). Conclusion: After 36 months of evaluation, the effectiveness of the LSTR technique with CTZ paste and pulpectomy with ZOE paste was similar for the treatment of primary molars with pulp necrosis. [ABSTRACT FROM AUTHOR]

Introduction: The objective of this study was to assess an original learning intervention to train students and paediatric dentistry teachers in radiographic diagnostic accuracy of pulpo‐periodontal complications in primary molars. Materials and Methods: The learning intervention was based on 250 different randomly ordered radiographs of primary molars within three quizzes (A, B and C) for 5 sessions (S): quiz A (50 X‐rays), B and C (100 X‐rays) were, respectively, completed in S1 to assess the extent of agreement with 5 experts' diagnoses, in S2 and S3 (B at days 8 and 23) and in S4 and S5 (C at days 90 and 105). During S1 and at the end of S3 and S5, the participants (48 students and 16 teachers) were informed of correct diagnoses. A satisfaction questionnaire was completed by all the students. Alongside the descriptive analyses, generalised linear mixed model (GLMM) analyses assessed the odds of participants' correct diagnosis over the study duration. Results: At S1, the odds of diagnostic accuracy among students were significantly lower than those among the teachers. After receiving feedback at S1, GLMM analyses showed that among all the participants, accuracy improved over time with the odds of correct diagnoses higher in S2‐5 than in S1; and there were similar increases across sessions between teachers and students, except in S3, where the improvement among teachers tended to be greater than that among the students. All students were satisfied though one‐third reported that quizzes with 100 radiographs felt too long. Conclusion: The online case‐based learning was a good training format for dental education. [ABSTRACT FROM AUTHOR]

Background: Manual or mechanized instruments can be used for root canal preparation. Manual instrumentation using K‐files is widely used in primary teeth, but there are many limitations. Mechanized root canal preparation can lead to easy access to all canals, decrease instrumentation time, and result in more funnel‐shaped root canals, resulting in a more predictable uniform paste fill. Aim: This study aimed to evaluate the shaping ability and instrumentation time of VDW.ROTATE™ and EdgeTaper Platinum™ during the preparation of resin‐printed primary molars. Hand K‐files were used as a reference for comparison. Design: Sixty‐six resin‐based maxillary second primary molars, obtained from extracted tooth cone‐beam computed tomography (CBCT) image and printed on a three‐dimensional printer, were divided into three groups: VDW.ROTATE™, EdgeTaper Platinum™, and K‐files. The specimens were scanned using CBCT imaging before and after root canal preparation. Images were registered using a dedicated software, and changes (Δ) in the canal area, volume, and untouched canal surface were calculated. Instrumentation time was evaluated. Data were statistically analyzed using the SPSS program. Results: There was no significant difference among the tested file systems for Δ canal volume and area (p >.05). VDW.ROTATE™, however, showed significantly lower untouched canal surface area than other systems in all roots (p <.001). The VDW.ROTATE™ was found to be significantly faster (6.47 ± 0.39 min) than EdgeTaper Platinum™ (7.71 ± 0.73 min) and K‐files (8.22 ± 0.72 min), (p <.05). Conclusions: The shaping ability and the instrumentation time were directly influenced by the root canal instrumentation system used during the preparation of resin‐printed primary molars, with VDW.ROTATE™ being the faster system and associated with the lower amount of untouched canal surface area. [ABSTRACT FROM AUTHOR]

This study aimed to compare the amount of debris extrusion of four endodontic systems made of Nickle‐Titanium alloy. This in vitro study was done on 80 extracted primary molars. They were selected by cone‐beam computed tomography and randomly divided into four groups (n = 20) to be prepared to the apical size of 25 by one of the systems: Reciproc, Protaper Universal, Neolix, or Hyflex CM. Debris was collected into Eppendorf microtubes and placed in an incubator to evaporate the washing solution. Debris was weighed by a digital scale of 0.01 g precision. Data were statistically analysed using SPSS software. Tukey's comparison was used to determine the difference between the four file systems (α = 0.05). Debris extrusion after Reciproc preparation (0.00320) was significantly higher than the other (P < 0.05), with no significant difference having been observed among the other systems (P > 0.05). It can be concluded that all systems under investigation exhibited debris extrusion. [ABSTRACT FROM AUTHOR]

Introduction: Evidence regarding the impact of early loss of primary molars (ELPM) on Oral Health‐Related Quality of Life (OHRQoL) is lacking. The aim of the present study was evaluating the impact of ELPM on OHRQoL of Brazilian schoolchildren aged 6–10 years. Methods: This observational prospective cohort study was conducted with 163 schoolchildren, assigned in the primary tooth loss group (PTLG), in which all tooth loss was caused by carious lesions, and in a control group without tooth loss (CG). Two calibrated examiners conducted the clinical oral assessments to determine caries experience and tooth loss. OHRQoL was assessed using the Child Perception Questionnaire 8–10 years (CPQ8‐10) instrument administered at baseline and at 10–12 months of follow‐up. Results: Children in PTLG exhibited significantly more negative impact on OHRQoL at baseline (p < 0.01) than CG, and also after the follow‐up period (p < 0.01). It was also possible to observe a significant reduction in the negative impact on OHRQoL in both CG and PTLG in the longitudinal analysis (p < 0.01). Nevertheless, there was an even more substantial reduction in the negative impact on OHRQoL in children in PTLG. Conclusions: This study provides evidence that early tooth loss is associated with negative impact on OHRQoL. Moreover, it indicates that access to dental treatment can have a positive impact on the OHRQoL of children with dental caries and ELPM. [ABSTRACT FROM AUTHOR]

Background: Prefabricated fibreglass crowns (PFCs) require less tooth structure reduction than prefabricated zirconium crowns (PZCs) for restoring primary molars. Little is known, however, about their mechanical properties. Aim: To investigate the fatigue survival and fracture resistance of PZCs and PFCs cemented with two different types of luting cement [glass‐ionomer cement (GIC) and resin‐modified GIC (RMGIC)]. Design: One hundred and twenty extracted human primary molars were randomly divided into subgroups (n = 15) according to the crown type (PFCs/PZCs), the luting cement (GIC/RMGIC) and crowns subjected to the chewing simulation test with thermocycling mechanical loading (CSTTML). The surfaces of the teeth were reduced by approximately 2 mm in the PZC group and 1 mm in the PFC group. All the samples were subjected to fracture tests. Results: None of the samples subjected to CSTTML exhibited signs of surface damage, fracture or premature debonding. The forces required to fracture PFCs were higher than those required for PZCs in all groups (p =.001). The highest mean fracture resistance values were obtained from the group of PFCs cemented with GIC that were subjected to the CSTTML (2515.8 N ± 619.2 N). Conclusions: PFCs presented high fatigue survival and could be used as alternatives to PZCs as they require less tooth structure reduction. Crowns cemented with GIC had a similar fracture resistance value when compared with RMGIC. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this retrospective study was to evaluate the outcome of preformed metallic crowns (PMC) utilizing the HT in carious primary molars for children treated within public dental clinics across the Sydney region. Materials and Methods: A retrospective cohort study was designed, whereby two investigators evaluated 113 primary molars treated with HT PMCs involving 71 participants (aged between 5 and 11 years) after a minimum of 6 months post treatment. The mean time elapsed between crown placement (treatment) and the review was 1.42 years (17 months). The outcome of the HT was assessed by clinical and radiographic criteria. Results: One hundred thirteen HT PMCs were reviewed from 71 participants. The overall success rate of PMCs placed utilizing the HT was 99%, with only one case presenting with confirmed failure. Conclusions: HT PMCs have an overall high success rate as a treatment option in carious primary molars. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to evaluate the effects of sealants in preventing pit and fissure caries in primary molars. The secondary objective was to assess the sealant retention during a 2‐yr study period. A 2‐yr split‐mouth randomized clinical trial including 90 3–7‐yr‐old children was conducted in the paediatric dental department of Montpellier hospital. The dentition of each included patient was divided into an experimental side and a control side, with annual follow‐up visits. Caries increments, measured as the number of new occlusal cavitated lesions, were not different between the sealed (mean 0.23) and the control primary molars (mean 0.29). A multiple mixed‐effects logistic regression showed that male gender, moderate/high caries risk, and a higher oral hygiene index score, had a statistically significant effect resulting in higher caries increments in the primary molars, than did female gender, low caries risk, and lower oral hygiene index scores. Sealing showed no statistically significant influence on the development of new caries lesions. After 2 yr, the percentages of partially or totally lost sealants were 22.7% and 32.0%, respectively. In this sample of children, the caries increment was not significantly different between the sealed and the unsealed molars. At the end of this 2‐yr study, more than half of the sealants were totally or partially lost, which could explain the low sealant effectiveness. [ABSTRACT FROM AUTHOR]

Background/aim: To investigate the susceptibility of Cusp of Carabelli (CoC) to caries in 3- to 4-year-old children.Methods: The prevalence of CoC was obtained, by two calibrated examiners using 2128 maxillary posterior sectional die models of 1064 caries-free children (that were prepared 8 months back). Four months after recording the CoC, prospective clinical examination of above-mentioned children was carried out by a calibrated third examiner. International Caries Detection and Assessment System was used to record caries of the mesiopalatal surfaces (site of CoC) of the primary maxillary second molars. Data were expressed in numbers and percentages and subjected to chi-square and logistic regression analyses.Results: The prevalence of CoC was 90.6%. The incidence of caries in association with CoC was 10.5%, and this association was statistically significant (0.004), with an odds ratio of 4.7. A statistically significant association was found between positive and negative expression of CoC and caries (0.001), with an odds ratio of 7.7 in positive expression and 4.1 in negative expression.Conclusion: The prevalence of CoC was high, with an increased risk for caries with a positive cusp expression. This highlights the need for closer assessment of the mesiopalatal surfaces of primary maxillary second molars during examination. [ABSTRACT FROM AUTHOR]

Background: Root canals of primary teeth are commonly prepared with endodontic files that are originally manufactured for permanent teeth. Aim: This micro‐computed tomography (micro‐CT) study evaluated and compared the changes in root canal morphology after preparation with different conventional and rotary files in primary teeth and young permanent teeth. Design: Seventy‐two extracted primary and permanent molars were selected and randomly assigned to three subgroups according to the file systems used (n = 12/each). After pre‐scanning of teeth with micro‐CT, root canals were prepared with One Shape and Revo‐S rotary systems and conventional endodontic files. After rescanning procedure, changes in canal volume, surface area, uninstrumented surface area, and apical transportation were evaluated. Mann‐Whitney U test, Kruskal‐Wallis test, and Conover's multiple comparison test were used for statistical analysis (P =.05). Results: Instrumentation with rotary files resulted in significantly greater volume and surface area of root canals and less uninstrumented areas (P <.001) than with manual files (P <.001). Primary molars showed significantly less apical transportation than permanent teeth (P <.001). Conclusions: Preparation of canals with rotary files could be a viable alternative to conventional files in primary teeth. Regardless of the file system used, uninstrumented areas still exist in both primary teeth and permanent teeth. [ABSTRACT FROM AUTHOR]

Objectives: Fluoride varnishes are reported to reduce 37-43% of dental caries; however, it remains unclear whether they can prevent severe decay. The study investigated the association between the government-supported preventive fluoride varnish application service (FVAS) and the risk of undergoing treatments of pulp-involved primary molars.Methods: Children who were younger than 6 years and did not receive any dental treatment between the first and last services within 2 years were defined as the "preventive-FVAS group." After the matching process, 45,296 children were selected for further analysis until the end of 2013. The log-rank test and Cox proportional hazard models were employed to estimate the effects of preventive-FVAS on the treatments of pulp-involved primary molars, including pulpectomy and early extraction before the age of 8 years.Results: After adjusting for confounding factors, adjusted hazard ratios for the treatments of pulp-involved primary molars for children who received preventive-FVAS were 0.96 (95% CI = 0.92-1.00) for initiation of pulpectomy, 0.93 (95% CI = 0.86-1.00) for completion of pulpectomy, and 0.87 (95% CI = 0.82-0.92, P < 0.0001) for early extraction, especially for those who received three or more FVAS.Conclusions: Although preventive-FVASs were associated with a 4-13% decreased risk of undergoing treatments of pulp-involved primary molars within a lower risk subset, we suggest the implementation the current Taiwan government-supported FVAS program needs to be modified. Further studies are warranted to evaluate whether it would be a better strategy if the program focused only on the high-risk group. [ABSTRACT FROM AUTHOR]

Background: The Hall Technique is a less invasive caries management technique for treating carious primary molars. It has become a routine treatment at specialists' practices. Aim: To retrospectively evaluate the clinical success and survival rates of preformed metal crowns placed on primary molars using the Hall Technique in a Paediatric Dentistry Setting. Design: Patient records of children receiving Hall crowns (with or without proximal slicing) between 2011 and 2017 were reviewed. Teeth with no clinical or radiographic evidence of pulp involvement at baseline and at least six months' follow‐up were included. Kaplan‐Meier survival analyses and Mantel‐Cox statistics were carried out. Results: In total, 181 Hall crowns performed in 2‐ to 10‐year‐olds with a mean follow‐up period of 22 months were included for analysis. Mean d3mft/D3MFT was 6.55 ± 3.48/0.18 ± 0.66. The majority of crowns were successful (92.3%; n = 167), four presented at least one minor failure (2.2%; reversible pulpitis, crown lost, or secondary caries) and ten were major failures (5.5%; irreversible pulpitis or abscess). When comparing crowns performed with no tooth preparation to crowns performed with proximal slicing, no differences were observed (P = 0.70, CI = 0.68‐0.83). Conclusion: The survival rate and clinical efficacy of Hall crowns were high in a secondary care‐based setting. The HT is an effective and less invasive management option for asymptomatic carious primary molars. [ABSTRACT FROM AUTHOR]

This study indented to assess the clinical and radiographic assessment of Allium sativum extract as an intracanal irrigant for pulpectomy of primary molars. Ninety children with 110 teeth submitted were categorized into two groups. Clinical and radiographic success rates were checked at 3, 6, and 12 months. Qui‐square test at a level of significance was ˂0.05. There was no statistically significant difference (p ˂ .05) between the two groups that has not been detected clinically or radiographically. Clinical and radiographic success rates of garlic extract at 3 months were (80% and 72.7%), which declined at 6 and 12 months to be 76.4% 6 and 74.5% respectively. For NaOCl group, clinical and radiographic success rates were 87.3% and 85.5% at 3 months, 87.3% and 87.3% at 6 months and 89.1% and 87.3% at 12 months. A. sativum extract can be used efficiently as an irrigant for pulpectomy of primary molar root canals. [ABSTRACT FROM AUTHOR]

Background: Evidence regarding the impact of premature loss of primary molars on oral health‐related quality of life (OHRQoL) is lacking. Aim: To evaluate the prevalence of premature loss of primary molars in schoolchildren and its impact on OHRQoL. Design: We randomly selected 667 children aged 8‐9 years enrolled in public and private schools from Aracaju (Brazil). The presence of untreated dental caries and early loss of primary molars were recorded, and its impacts on OHRQoL evaluated using Child Perceptions Questionnaire (CPQ8‐10). Influence of some variables on tooth loss and OHRQoL was assessed by multilevel Poisson's regression analysis (P < 0.05). Results: The prevalence for early tooth loss was 65.4% (95% confidence interval 51.1%‐77.3%). Children with untreated dental caries and attending public schools presented higher prevalence of early tooth loss. Moreover, early loss of primary molars provoked negative impact on OHRQoL considering total score of CPQ8‐10 and domains "oral symptoms," "functional limitations" and "emotional well‐being." Children presenting early teeth loss presented significantly higher scores of CPQ8‐10, as well as females and children with dental caries in other teeth. Conclusions: The prevalence of early loss of primary molars is high, and it impacts the OHRQoL of children aged 8‐9 years. [ABSTRACT FROM AUTHOR]

Paediatric endodontics is an integral part of dental practice that aims to preserve fully functional primary teeth in the dental arch. Pulpectomy of primary molars presents a unique challenge for dental practitioners. Negotiation and thorough instrumentation of bizarre and tortuous canals encased in roots programmed for physiological resorption are the main challenges for this treatment approach. Consequently, numerous in vitro and in vivo studies have been conducted to validate the application of some contemporary endodontic armamentarium for effective treatment in primary molars whilst maintaining favourable clinical outcomes. Electronic apex locators, rotary nickel-titanium files and irrigation techniques are at the forefront of endodontic armamentarium in paediatric dentistry. Hence, this review aims to map out the root and root canal morphology of primary molars, to discuss the application of electronic apex locators in primary molars and to provide an update on the preparation of their root canal systems. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to clinically examine the efficacy of tunnel preparations in primary molars restored with glass-ionomer cement during a 36-month observation period. Methods: A total of 233 tunnel restorations were placed in primary molars of 203 patients aged 6–10 years. Restorations were evaluated after 12, 24 and 36 months using the modified USPHS criteria for secondary caries, marginal discolouration, marginal adaptation and anatomic form. The Alpha+Bravo score (except for caries) and absence of clinical signs of endodontic complications was considered as a clinical success. Results: At the end of the 36-month experimental period, the cumulative survival rate of tunnel restorations in primary molars was 72 per cent. The main reasons for failure were endodontic complications (46 per cent of the failures), secondary caries (31 per cent of the failures) and marginal ridge fractures (19 per cent of the failures). Conclusions: The tunnel preparation filled with reinforced restorative glass-ionomer cement is a suitable treatment for minimal proximal caries lesions in primary molars. [ABSTRACT FROM AUTHOR]

The objectives of this study were to clinically evaluate the effectiveness of 2% buffered glutaraldehyde in pulpotomies of human primary molars and to compare the success rate of glutaraldehyde with calcium hydroxide and glutaraldehyde with zinc oxide eugenol as dressing material on the radicular pulp. Pulpotomies were completed on 61 primary molars in 19 children. The teeth were divided into two groups by random allocation. One group had a dressing of zinc oxide-eugenol base (IRM) incorporated with one drop of 2% buffered glutaraldehyde while the other group had a dressing of calcium hydroxide base incorporated with one drop of 2% buffered glutaraldehyde after the initial placement of 2% buffered glutaraldehyde on cotton pellet for 3 min. All teeth had light-curing compomer (Dyract) placed over the dressing material followed by a stainless steel crown restoration within 1 or 2 weeks after the pulpotomy. Blind clinical and radiographic evaluations of 57 teeth available after 12 months showed a success rate of 92.9% and 73.6% respectively. The clinical and radiographic success rates for glutaraldehyde/zinc oxide eugenol pulpotomies were 96.5% and 75.8% respectively while those for glutaraldehyde-calcium hydroxide were 89.2% and 71.4%. There was no statistically significant difference between the two groups either clinically or radiographically. The overall clinical success rate suggested that 2% buffered glutaraldehyde was an effective agent in the pulpotomy of human primary molars. [ABSTRACT FROM AUTHOR]

The life-span of amalgam restorations placed in primary molars by three general dental practitioners is investigated. Two methods of analysis have been carried out. In the analysis of "non-independent" restorations (i.e. using several restorations from each mouth), the median survival time was 52.8 months with an apparent standard error of 2.1 months. In the analysis of "independent" restorations (i.e. only using one restoration from each mouth), three random samples were chosen and their median survival times were 68.2 months (s.e.= 6.9), 60.5 months (s.e.= 6.9), and 56.8 months (s.e. = 3.7). The two methods are compared and discussed. It is concluded that the analysis of "independent" restorations should be the method of choice in studying the life-span of restorations. [ABSTRACT FROM AUTHOR]

The view that primary teeth are only rarely affected by periodontitis has been generally adopted. The aim of the present work was to measure attachment loss and to establish its prevalence, severity and distribution in stained, extracted primary molars. The material consisted of 4 groups of 50 teeth each: first and second upper and first and second lower primary molars. Teeth were selected to fulfil 2 criteria: (1) a carious cavity not extending beyond the cemento-enamel junction and involving only 1 of the proximal surfaces, the other 3 surfaces being sound: (2) root resorption, if present, not affecting more than the apical third of the roots. The teeth were stained in 1% aqueous crystal violet and examined under a stereomicroscope fitted with an ocular micrometer. The distance between the cemento-enamel junction and the most coronal attachment fibres was measured in the mid-line of each surface. Attachment loss was found in 94% of the teeth and on &frac;23 or the surfaces. This indicates that periodontitis in primary teeth is not a rare phenomenon. The mean loss of attachment was 0.26±0.32 mm, which cannot he regarded as clinically important. The maxillary molars and the first molars, and, the proximal surfaces showed more loss of attachment than did the mandibular molars and the second molars, and the buccal and lingual surfaces taken together. This pattern of attachment loss is similar to that seen in permanent molars. On the carious proximal surfaces, significantly more attachment loss was noted than on the sound proximal surfaces. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to introduce and discuss four indices to be used in epidemiologic recording of pulp treatment and extraction of primary molars. The indices are constructed on the basis of the four combinations existing between pulp treatment/no pulp treatment and extraction/no extraction. The NPE-index (No Pulptreatment or Extraction) reflects the relative number of teeth which are neither extracted nor pulp treated. EPM-index (Extracted Primary Molars) reflects the relative number of teeth, which have been extracted. PPM-index (Pulp treatment Primary Molars) reflects the ralative number of teeth which have been pulp treated. PNE-index (Pulp treatment No Extraction) reflects the relative number of pulp treated and not extracted teeth. [ABSTRACT FROM AUTHOR]

The width of plaque-free zones on stained surfaces of extracted primary molars showing attachment loss was measured. The teeth were divided into 4 groups: maxillary first and second molars, mandibular first and second molars. 30 measurements were made under a stereomicroscope on each of the 4 surfaces in every group. The plaque-free zone had a mean width of 1.75±0.49 mm and a range of 1.0-4.3 mm. The plaque-free zone was significantly (P < 0.001) wider on the proximal surfaces (1.94 ± 0.56 mm) than on the combined buccal and lingual surfaces (1.56 ± 0.32 mm). There was no difference between the 2 proximal surfaces while the lingual surfaces gave higher values than the buccal ones. On the second and on the lower primary molars, the plaque-free zones were wider than on the first and on the upper molars. [ABSTRACT FROM AUTHOR]