Human Primary Molars Research Articles

A study of root canal morphology of human primary incisors and molars using cone beam computerized tomography: An in vitro study

Variations in morphology of root canals in primary teeth usually leads to complications during and after endodontic therapy. To improve the success in endodontics, a thorough knowledge of the root canal morphology is essential. The aim of this study was to assess the variation in number and morphology of the root canals of primary incisors and molars and to study the applicability of cone beam computerized tomography (CBCT) in assessing the same. A total of 60 primary molars and incisors with full root length were collected and various parameters such as the number of roots, number of canals, diameter of root canal at cementoenamel junction and middle-third, length and angulations of roots of primary molars and incisors were studied using CBCT. The observations were put to descriptive statistics to find out the frequency, mean, standard deviation and range for all four subgroups. Further, unpaired t-test was used to compare these parameters between subgroups and analysis of variance test was implemented to evaluate the parameters within the subgroups. The CBCT showed the presence of bifurcation of root canal at middle third in 13% of mandibular incisors while 20% of mandibular molars had two canals in distal root. The diameter of distobuccal root canal of maxillary molars and mesiolingual canal of mandibular molars was found to be minimum. CBCT is a relatively new and effective technology, which provides an auxiliary imaging modality to supplement conventional radiography for assessing the variation in root canal morphology of primary teeth.

Root canal morphology of human primary maxillary molars in Indian population using spiral computed tomography scan: An in vitro study

Aim: The aim of the study was to evaluate the root canal morphology of primary maxillary molars in Indian population using spiral computed tomography (SCT). Materials and Methods: The 30 extracted primary maxillary molars were collected. The teeth were scanned using SCT. The scanned data was then transferred to image analysis software and evaluated for the following: Distance between the central fissure to furcation, distance between the central fissure to the floor of the pulp chamber, height of the pulp chamber (roof-floor), distance between the floor of the pulp chamber to the furcation and number of canals. Results: The results of this study shows that the average mean distance from the central fissure to the floor of the pulp chamber is 5.02 mm and 5.32 mm in first maxillary primary molar and second maxillary primary molar. Conclusion: Knowledge of the root canal morphology and anatomical landmarks of the primary maxillary molar might be a very helpful indicator to the dentist during access opening.

Simvastatin versus Calcium Hydroxide Direct Pulp Capping of Human Primary Molars: A Randomized Clinical Trial.

Background and aims The aim of present study was to investigate pulp-dentin complex reactions following direct pulp capping (DPC) with calcium hydroxide [Ca(OH)2] and simvastatin as pulp-capping materials in the primary human molars. Materials and methods 120 primary molar teeth which had to be extracted for orthodontic reasons were randomly allocated into four groups. Group Ι as a control, underwent DPC with calcium hydroxide. The dental pulp in group ІІ, ІІІ and ІV were directly capped with simvastatin-based materials at concentrations of 1, 5 and 10 µM, respectively. All of the teeth were restored with stainless steel crown. After a mean period of 7.41 months teeth were extracted and processed for histological examination and categorized in terms of hard tissue formation and pulp inflammation. Results Teeth in group I had statistically favorable outcomes in hard tissue formation and pulp inflammation than did the groups ІІ, ІІІ and ІV (P < 0.001). Considering three different concentrations of simvastatin, the result showed a dose dependent trend. Teeth in group ІV showed significantly lower rates of hard tissue formation and higher rates of pulp inflammation and necrosis compared to those of groups ІІ (P < 0.05). Conclusion The findings of this study depicted that healing with no inflammation and hard tissue formation following statin treatment occurs with a lower rate than that with the calcium hydroxide.

Effect of thermo-mechanical loading on marginal quality and wear of primary molar crowns

To evaluate the effect of thermo-mechanical loading (TML) on marginal quality and wear of different crown types for primary molars. Eighty extracted human primary molars were used. After preparation, five groups received different crowns (n=16): preformed metal crowns (3M ESPE) and NuSmile crowns (Orthodontic Technologies Inc.) were inserted as preformed metal crowns; as semi-preformed crowns Protemp crowns (3M ESPE) were luted; and as individually manufactured resin composite crowns Filtek Z250 (3M ESPE) and Heliomolar (Ivoclar Vivadent) were used. Specimens were subjected to 2,500 thermal cycles between 5-55(o)C and chewing simulation for 100,000 cycles at 50N at a frequency of 0.5 Hz. Before and after thermo-mechanical loading, impressions of the teeth were taken and replicas were made. The replicas received marginal quality evaluation under a SEM at x200 magnification. Occlusal wear was measured as vertical height loss using a 3-D laser scanning microscope. After TML, all crowns were intact. The adhesively bonded crowns showed significantly better marginal quality to dentine/cementum compared with GIC luted crowns (p<0.05). Laboratory made crowns showed a good fit and nearly transition-free margins also after TML. Preformed metal crowns showed the significantly lowest wear rates compared to the resin composites (p<0.05). Among the resin composite groups, Protemp exhibited the most pronounced wear depths (p<0.05). The different crown types under investigation showed a good performance concerning the evaluated parameters marginal quality and wear.

Effect of Nd:YAG laser combined with fluoride on the prevention of primary tooth enamel demineralization

Most studies dealing with the caries preventive action of Nd:YAG laser have been done in permanent teeth and studies on primary teeth are still lacking. The aim of this study was to evaluate in vitro the effect of Nd:YAG laser combined or not with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction by assessing longitudinal microhardness and demineralization depth. Sixty enamel blocks obtained from the buccal/lingual surface of exfoliated human primary molars were coated with nail polish/wax, leaving only a 9 mm² area exposed on the outer enamel surface, and randomly assigned to 6 groups (n=10) according to the type of treatment: C-control (no treatment); APF: 1.23% acidulated phosphate fluoride gel; FV: 5% fluoride varnish; L: Nd:YAG laser 0.5 W/10 Hz in contact mode; APFL: fluoride gel + laser; FVL: fluoride varnish + laser. After treatment, the specimens were subjected to a des-remineralization cycle for induction of artificial caries lesions. Longitudinal microhardness data (%LMC) were analyzed by the Kruskal-Wallis test and demineralization depth data were analyzed by oneway ANOVA and Fisher's LSD test (á=0.05). APFL and APF groups presented the lowest percentage of microhardness change (p<0.05). Demineralization depth was smaller in all treated groups compared with the untreated control. In conclusion, Nd:YAG laser combined or not with fluoride gel/varnish was not more effective than fluoride alone to prevent enamel demineralization within the experimental period.

Comparison of Electrosurgical Pulpotomy with Zinc Oxide Eugenol or Zinc Polycarboxylate Cements Sub-Base

The aim of this study was to compare the clinical and radiographic success rates of electrosurgical pulpotomy of human primary molars with zinc oxide eugenol (ZOE) and zinc polycarboxylate (ZPC) cements. In this randomized clinical trial study, 120 primary second molar teeth were treated by electrosurgical pulpotomy. Teeth were randomly assigned to two groups according to whether ZOE or ZPC cement was used as a sub-base. Teeth were restored with stainless steel crowns and were evaluated clinically and radiographically after 3, 6, and 12 months by two independent examiners. Clinical treatment outcomes and radiographic findings were statistically analyzed using Fishers' exact test with statistically significant differences defined for P < 0.05. At 12 months, the clinical and radiographic success rates in the ZOE group were 98.2% and 84.2% and in the ZPC group were 96.2% and 75%, respectively (P > 0.05 for all). The outcomes of this study suggested that either ZPC or ZOE sub-base have similar clinical and radiographic success in electrosurgical pulpotomy.

Evaluation of Pulpal Blood Flow Changes in Primary Molars with Physiological Root Resorption by Laser Doppler Flowmetry and Pulse Oximetry

The aim of this study was to undertake a comprehensive quantitative investigation ofpulpal bloodflow (PBF) changes in human non-carious primary molar teeth with variable degrees of root resorption by Laser Doppler Flowmetry (LDF) and Pulse Oximetry (PO) methods. Data was collected from clinically and radiographically healthy 86 mandibular primary molars which have different physiological root resorption levels (PRRLs). PRRLs for each of the teeth were assessed using periapical radiographs and teeth were subdivided into three groups. The LDF values demonstrated a significant diference (p = 0.0001) between all groups although PO did not demonstrate any difference (p = 0.109). Statistical analysis of LDF values demonstrated significant differences between Groups A and C (p = 0.0001) and Groups B and C (p = 0.008). Furthermore, positive correlations were determined between LDF values and PRRL groups (p = 0.0001) and patients' ages (p = 0.0001). In our study, it was observed that the PBF values of human primary molars measured by LDF tended to increase with the progress of physiological root resorption and age. LDF was found to be a more effective method than PO to assess the pulpal vascularity changes of human primary molars.

Effect of Multiple Coatings of One-step Self-etching Adhesive on Microtensile Bond Strength to Primary Dentin

To investigate the effect of multiple coatings of the one-step self-etching adhesive on immediate microtensile bond strength to primary dentin. Twelve caries-free human primary molars were randomly divided into 2 groups with 6 teeth each. In group 1, each tooth was hemisected into two halves. One half was assigned to control subgroup 1, which was bonded with a single-step self-etching adhesive according to the manufacturer's instructions; the other half was assigned to experimental subgroup 1 in which the adhesive was applied three times before light curing. In group 2, the teeth were also hemisected into two halves. One half was assigned to control subgroup 2, which was bonded with the single-step self-etching adhesive according to the manufacturer's instructions; the other half was assigned to experimental subgroup 2 in which three layers of adhesive were applied with light curing each successive layer. Microtensile bond strength was immediately tested after specimen preparation. When the adhesive was applied three times before light curing, the bond strength of the experimental subgroup 1 (n=33, 57.49 +/-11.61 MPa) was higher than that of the control subgroup 1 (n=31, 49.71 +/-11.43 MPa, P<0.05). When using the technique of applying multiple layers of adhesive with light curing each successive layer, no difference of immediate bond strength was observed between the control subgroup 2 and the experimental subgroup 2 (P>0.05). strength to primary dentin when using the technique of light-curing after applying three layers of adhesive.

Effect of tube potential and image receptor on the detection of natural proximal caries in primary teeth

The aim of this study was to assess the detection of proximal caries in primary teeth at three different tube potentials using Ektaspeed films, storage phosphor plates (SPPs), and a charge-coupled device (CCD). Fifty-three extracted human primary molars with natural proximal caries were radiographed with three different imaging modalities--Digora Optime SPP system, RVGui CCD system, and Ektaspeed films--at 50-, 65-, and 70-kV tube potentials. Three observers scored the resultant images for the presence or absence of caries. The definitive diagnosis was determined by stereomicroscopic assessment. The diagnostic accuracy for each imaging modality was expressed as the area under the receiver operating characteristic curves (A(z)). Differences among the A(z) values were assessed using two-way ANOVA and t tests. Kappa was used to measure inter- and intra-observer agreement. Higher accuracy was found for SPPs compared to film and CCD images at all tube potentials. Accuracy was significantly different only at 50-kV tube setting in favor of SPPs (p < 0.05). Inter- and intra-observer agreement was high for all systems. A SPP system can be recommended for dental peadodontic clinics particularly with 50-kV tube potential for the diagnosis of proximal caries since further advantages include the elimination of chemical processing, image enhancement, and a better low-contrast detectability performance.

Temperature rise during Er:YAG cavity preparation of primary enamel

This study aimed to assess in vitro thermal alterations taking place during the Er:YAG laser cavity preparation of primary tooth enamel at different energies and pulse repetition rates. Forty healthy human primary molars were bisected in a mesio-distal direction, thus providing 80 fragments. Two small orifices were made on the dentin surface to which type K thermocouples were attached. The fragments were individually fixed with wax in a cylindrical Plexiglass® abutment and randomly assigned to eight groups, according to the laser parameters (n = 10): G1 - 250 mJ/ 3 Hz, G2 - 250 mJ/ 4 Hz, G3 - 250 mJ/ 6 Hz, G4 - 250 mJ/10 Hz, G5 - 250 mJ/ 15 Hz, G6 - 300 mJ/ 3 Hz, G7 - 300 mJ/ 4 Hz and G8 - 300 mJ/ 6 Hz. An area of 4 mm(2) was delimited. Cavities were done (2 mm long × 2 mm wide × 1 mm thick) using non-contact (12 mm) and focused mode. Temperature values were registered from the start of laser irradiation until the end of cavity preparation. Data were analyzed by one-way ANOVA and Tukey test (p ≤ 0.05). Groups G1, G2, G6, and G7 were statistically similar and furnished the lowest mean values of temperature rise. The set 250 mJ/10 and 15 Hz yielded the highest temperature values. The sets 250 and 300 mJ and 6 Hz provided temperatures with mean values below the acceptable critical value, suggesting that these parameters ablate the primary tooth enamel. Moreover, the temperature elevation was directly related to the increase in the employed pulse repetition rates. In addition, there was no direct correlation between temperature rise and energy density. Therefore, it is important to use a lower pulse frequency, such as 300 mJ and 6 Hz, during cavity preparation in pediatric patients.

Formocresol versus Calcium Hydroxide Direct Pulp Capping of Human Primary Molars: Two Year Follow-Up

Clinical and radiographic evaluation of the premedicated direct pulp capping using formocresol (PDC) versus conventional direct pulp capping using calcium hydroxide (CDC) in human carious primary molars. A total of 120 vital primary molars with pinpoint exposure during caries removal in 84 patients aged 4-5 years were selected. In the PDC group (n = 60), 20% Buckley's formocresol solution, and in the CDC group (n = 60), calcium hydroxide powder were applied to the exposure sites followed by placement of zinc oxide-eugenol base. Teeth were restored with preformed stainless steel crowns. Clinical and radiographic evaluations of the treatment outcomes were performed at regular intervals of 6 and 12 months, respectively, for two years post-operatively. The prevalence of spontaneous pain, sensitivity on percussion, and fistula were significantly higher in the CDC group compared to the PDC group (P < 0.05). The number of teeth exhibiting periapical/furcal radiolucency or external/internal root resorption was also higher in the CDC group (P < 0.05). The clinical success rate of the PDC was 90% compared to the 61.7% of the CDC (P < 0.05). The radiographic success rates of the PDC and CDC groups were 85% and 53.3%, respectively (P < 0.05). It seems formocresol premedicated direct pulp capping could safely be used as a substitute for conventional direct pulp capping.

Retentive Strength of Luting Cements for Stainless Steel Crowns: An in vitro Study

The present study evaluated and compared the retentive strength of three luting cements. A total of forty five freshly extracted human primary molars were used in this study. The teeth were prepared to receive stainless steel crowns. They were then randomly divided into three groups, of fifteen teeth each, so as to receive the three different luting cements: conventional glass ionomer resin modified glass ionomer and adhesive resin. The teeth were then stored in artificial saliva for twenty four hours. The retentive strength of the crowns was determined by using a specially designed Instron Universal Testing Machine (Model 1011). The data was statistically analyzed using ANOVA to evaluate retentive strength for each cement and Tukey test for pair wise comparison. It was concluded that retentive strength of adhesive resin cement and resin modified glass ionomer cement was significantly higher than that of the conventional glass ionomer cement.

Technique-sensitivity of dentin-bonding agent application: The effect on shear bond strength using one-step self-etch adhesive in primary molars: An in vitro study

The present study was undertaken to compare and evaluate the effect of technique-sensitivity on shear bond strength (SBS) of one-step self-etch adhesive, using multiple coats and different applicator designs, to dentin in deciduous molars. Flat buccal dentinal surfaces were obtained on 60 extracted human primary molars. The specimens were divided into 3 equal groups (n = 20). Self-etch adhesive was applied on the dentinal surface of group I with cotton pellet, group II with microapplicator tip, and group III using 3M brush. The groups were further divided into 2 subgroups-single coat of dentin-bonding agent (DBA) in subgroups A and triple coat (with no curing in between coats) in subgroups B. The composite was placed on the dentinal surface using split nylon cylinder and cured. SBS was tested for all specimens with Instron Universal testing machine. Data were statistically analyzed using one-way analysis of variance and Student's t test. There was no statistically significant difference in the main study groups, that is, no significant difference in the SBS with the use of different applicator tips. However, the use of triple coat of self-etch DBA exhibited highly significant difference in the SBS as compared with single coat. This study revealed that one-step self-etch adhesive could prove attractive in pediatric dentistry because of its lesser technique-sensitivity; however, increasing the number of coats of DBA (with no curing in between the layers) enhanced the bond strength to dentin owing to the improved resin infiltration.

A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study

An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ). Negligible difference (0.59 kg/cm 2 ) of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 ) and glass ionomer cements (20.69 kg/cm 2 ). Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

Summary of: Pulpotomy of human primary molars with MTA and Portland cement: a randomised controlled trial

Objective This study compared the clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) and Portland cement (PC) as pulp dressing agents in carious primary teeth. Methodology Thirty carious primary mandibular molars of children aged 5-9 years old were randomly assigned to MTA or PC groups, and treated by a conventional pulpotomy technique. The teeth were restored with resin modified glass ionomer cement. Clinical and radiographic successes and failures were recorded at 6, 12, 18 and 24-month follow-up. Results All pulpotomised teeth were clinically and radiographically successful at all follow-up appointments. Six out of 15 teeth in the PC group and five out of 14 teeth in the MTA group exfoliated throughout the follow-up period. No statistically significant difference regarding dentine bridge formation was found between both groups throughout the follow-up period. As far as pulp canal obliteration is concerned, a statistically significant difference was detected at 6-month follow-up (p <0.05), since the beginning of mineralised material deposition could be radiographically detected in 100% and 57.14% of the teeth treated with PC and MTA, respectively. Conclusions PC may serve as an effective and less expensive MTA substitute in primary molar pulpotomies. Further studies and longer follow-up assessments are needed.

Pulpotomy of human primary molars with MTA and Portland cement: a randomised controlled trial

This study compared the clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) and Portland cement (PC) as pulp dressing agents in carious primary teeth. Thirty carious primary mandibular molars of children aged 5-9 years old were randomly assigned to MTA or PC groups, and treated by a conventional pulpotomy technique. The teeth were restored with resin modified glass ionomer cement. Clinical and radiographic successes and failures were recorded at 6, 12, 18 and 24-month follow-up. All pulpotomised teeth were clinically and radiographically successful at all follow-up appointments. Six out of 15 teeth in the PC group and five out of 14 teeth in the MTA group exfoliated throughout the follow-up period. No statistically significant difference regarding dentine bridge formation was found between both groups throughout the follow-up period. As far as pulp canal obliteration is concerned, a statistically significant difference was detected at 6-month follow-up (p <0.05), since the beginning of mineralised material deposition could be radiographically detected in 100% and 57.14% of the teeth treated with PC and MTA, respectively. PC may serve as an effective and less expensive MTA substitute in primary molar pulpotomies. Further studies and longer follow-up assessments are needed.

Comparative Evaluation of Carisolv in Removal of Carious Dentin in Primary Molar Teeth: in vitro Study

Resumen en: Objective: To evaluate and compare the efficiency and effectiveness of Carisolv in caries removal in human primary molars. Method: 30 primary molar cario...

Use of focused ion beam milling for investigating the mechanical properties of biological tissues: A study of human primary molars

In this paper, the usefulness of the specimen shaping ability of focused ion beam (FIB) milling in the micrometer scale and the high force resolution of the nanoindentation technique are demonstrated on human primary teeth. Micro-cantilevers, with a triangular cross-section <5 μm in width and 10 μm in length, were produced within 50 μm of the dentin–enamel junction (DEJ) using FIB milling, and were point-loaded at their free ends at 20 μN/s until failure using a nanoindenter. The elastic modulus and flexural strength of such micro-samples of human enamel, and their variation with respect to prism orientation, were studied and compared to data from bulk enamel measured using nanoindentation and three-point bend tests. The elastic modulus of the micro-cantilever samples was found to be comparable to that obtained by nanoindentation on bulk samples, but it demonstrated significant anisotropy commensurate with the microstructure of enamel which was not measurable using nanoindentation on bulk samples. The flexural strength of the enamel micro-cantilevers also exhibited strong anisotropy, and was about one order of magnitude higher than that of bulk specimens measured by three-point bending. Through a Weibull analysis, this size dependence of the strength was found to be similar to the normal behaviour in brittle materials. The flexural strength of the enamel samples was also found to be sensitive to changes in the degree of mineralization of the samples.

Pulpotomies with portland cement in human primary molars

Two clinical cases in which Portland cement (PC) was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended.

Adhesion to Primary and Permanent Dentin and a Simple Model Approach

First to compare different dentin bonding agents' shear bond strength to primary and permanent dentin. Secondly to compare the fracture failure modes and making an attempt to develop a statistical model that could be helpful in predicting them. Extracted human primary and permanent molars were used as substrates (dentin). The shear bond strength of composite to substrate was measured and fracture surfaces were evaluated visually and with stereomicroscope. Using the data obtained, a statistical model was built in order to predict the failure modes. Higher bond strength values were obtained for permanent dentin. Total-etch adhesives displayed higher shear bond strength values than the self-etch adhesive. Adhesive failures were more frequently seen in primary dentin. Self-etch adhesive system displayed more adhesive failures. Prepared model confirmed the negative relationship between shear bond strength and the probability of observing adhesive failure. There should be an application protocol for the usage of dentin bonding agents in primary dentin. Further development of statistical and fuzzy models for failure modes can be supportive alternatives for microscopic evaluations and also be helpful in understanding and eliminating the factors which are responsible for the formation of adhesive failures and for achieving clinically more successful adhesive restorations.