Effect of apical root resection, orthodontic extrusion, and surgical crown lengthening on load capability.

OBJECTIVES: This study aims to investigate the load-to-fracture of procedures changing crown-to-root ratio (RCRR) aimed to restore severely damaged upper central incisors to avoid tooth extraction compared to implant placement. There is no evidence on load capability after apical root resection (AR), orthodontic extrusion (OE), and surgical crown lengthening (SCL) in respect to RCRR, respectively. MATERIAL AND METHODS: Human maxillary central incisors were endodontically treated, decoronated, and divided into 4 groups (n = 48). The following specimen preparation was performed: (I) adhesive core-and-post build-up (control), (II) as (I) and 2 mm apical root resection (AR), (III) before adhesive core-and-post build-up teeth were shortened 2 mm coronally (OE) (IV) as (I), but specimens were embedded 4 mm instead of 2 mm below the CEJ (SCL), group (V) implant-borne restoration with individual all-ceramic abutments (n = 12; ∅4.1/l = 12 mm) (IBR). All specimens received all-ceramic crowns, thermo-mechanical (TML), and subsequent linear loading (LL) until failure. RCRR were calculated and log-rank, Kruskal-Wallis, Mann-Whitney U, ANOVA, and chi-square tests applied (p = 0.05). RESULTS: Fracture loads after subsequent LL differed significantly (p = 0.001) between groups, while implants showed the highest values. Fmax median (min/max) were as follows: (I) 252 (204/542), (II) 293 (243/443), (III) 253 (183/371), (IV) 195 (140/274), and (V) 446 (370/539). Pair-wise comparison showed significant differences (p = 0.001) between group I/IV and group V, I, and IV (p = 0.045), II and IV (p = 0.001), and III compared to IV (p = 0.033), respectively. RCRR below 1 significantly increased load capability compared to RCRR = 1. CONCLUSIONS: OE appears to preferably ensure biomechanical stability of teeth that are endodontically treated and receive core-and-post and crown placement compared to SCL. AR has no adverse biomechanical impact. RCRR < 1 is biomechanically beneficial. CLINICAL RELEVANCE: For endodontically treated and restored teeth, orthodontic extrusion should be preferred compared to surgical crown lengthening prior single-crown restoration. As orthodontic extrusion, apical root resection has no adverse effect on load capability. Single-crown implant-borne restorations are most load capable.

Direct restoration of endodontically treated maxillary central incisors: post or no post at all?

OBJECTIVES: The aim of this ex-vivo study was to evaluate the impact of cavity size and glass-fiber post (GFP) placement on the load capability of endodontically treated maxillary incisors directly restored with resin composite. MATERIALS AND METHODS: Ninety-six extracted human maxillary central incisors were endodontically treated and distributed to four groups (n = 24): access cavity (A), access cavity and uni-proximal class III cavity (U), access cavity and bi-proximal class III cavity (B), and decoronated tooth (D). Specimens were restored with resin composite, and 12 specimen of each group received an adhesively placed glass-fiber post (P). Prior to linear loading, specimens were exposed to thermo-mechanical loading (TCML). Statistical analysis was performed using log-rank test after TCML, Kruskall-Wallis and Mann-Whitney U test to compare load capabilities (Fmax). RESULTS: Significantly more failures occurred in group D for specimens without GFP during TCML (p = 0.001). Fmax (mean (SD) in N was (A) 513 (124), (AP) 554 (201), (U) 438 (171), (UP) 537 (232) (B) 483 (219), (BP) 536 (281), D 143 (181), and DP 500 (331), and differed significantly among groups (p = 0.003). Pair-wise comparison revealed lower Fmax values for group D compared to all other groups (p < 0.034) except group DP. CONCLUSIONS: Endodontically treated maxillary central incisors with cavity sizes up to bi-proximal class III may be successfully directly restored with resin composite. Post placement shows no additional effect except for decoronated endodontically treated incisors. CLINICAL RELEVANCE: Endodontically treated incisors with access cavities to class III cavities can be successfully restored with resin composite. Post placement for decoronated ETT is recommended.

Adhesive luting of new CAD/CAM materials.

OBJECTIVE: To evaluate the adhesive bonding performance of recently introduced tooth-colored CAD/CAM materials after different pretreatment protocols and using different luting materials. MATERIALS AND METHODS: The CAD/CAM materials under investigation were e.max CAD (lithium disilicate glass ceramic; Ivoclar Vivadent, Schaan, Liechtenstein), Celtra Duo (zirconia-reinforced lithium disilicate ceramic; Dentsply DeTrey, Konstanz, Germany), Lava Ultimate (resin nano ceramic; 3M ESPE, Neuss, Germany), and Enamic (resin infiltrated ceramic; Vita, Bad Säckingen, Germany). A total of 240 blocks (n = 5) received various pretreatments (no pretreatment, silane, sandblasting, sandblasting + silane, hydrofluoric acid, hydrofluoric acid + silane), and then different classes of adhesive luting composites were applied (adhesive: Prime&Bond XP + SCA + Calibra; Dentsply DeTrey; self adhesive: RelyX Unicem; 3M ESPE). After 24 h water storage and 10,000 thermocycles (5°C/55°C), specimens were cut into beams and microtensile bond strengths were recorded. RESULTS: Bonding performance of recent CAD/CAM materials was clearly influenced by the pretreatment method (P < 0.05). In general, significantly higher µ-TBS values were recorded for the ceramic materials compared to the hybrid materials (P < 0.05). Among the hybrid materials, Enamic exhibited higher bond strengths than Lava Ultimate (P < 0.05). However, despite the differences found, all materials showed a high level of bonding performance, being sufficient to withstand intraoral chewing forces during mastication. CONCLUSION: When pretreated as recommended by the manufacturers, recent tooth-colored CAD/CAM materials show an encouraging bonding performance for adhesive luting.

Clinical effectiveness of pit and fissure sealants in primary and permanent teeth of children and adolescents: an umbrella review.

PURPOSE: This umbrella review aimed to critically appraise the evidence published in systematic reviews (SRs) on the clinical effectiveness of sealants compared with each other/the non-use in primary/permanent teeth of children and adolescents with at least 12-month follow-up. METHODS: A systematic literature search on 4 electronic databases was conducted up to January 18th, 2023. Following handsearching, two review authors independently screened retrieved articles, extracted data, and assessed the risk of bias (RoB) using the risk of bias in systematic reviews (ROBIS) tool. Based on a citation matrix, the overlap was interpreted by the corrected covered area (CCA). RESULTS: Of 239 retrieved records, 7 SRs met the eligibility criteria with a moderate overlap among them (CCA = 7.4%). For primary molars, in 1120 1.5- to 8-year-old children, data on the clinical effectiveness of sealants were inconclusive. For permanent molars, 3 SRs found a significant caries risk reduction for sealants versus non-use (≤ 36-month follow-up). There was insufficient evidence to proof superiority of sealants over fluoride varnish for caries prevention (3 SRs), and to rank sealant materials according to the best clinical effectiveness in permanent molars. One study was rated at low and 6 at high RoB, which did not allow for a valid quantitative synthesis. CONCLUSION: Considering the limitations of this umbrella review, sealants are more effective for caries prevention in children's permanent molars compared to no treatment. Future well-implemented RCTs are needed to draw reliable conclusions on the clinical effectiveness of sealants in primary and permanent teeth of children and adolescents.

Are implants more reliable than severely compromised endodontically treated teeth as abutments for zirconia-based FPDs? : In vitro results of long-term preclinical load simulation.

OBJECTIVES: The aim was to study the impact of the defect size of endodontically treated incisors compared to dental implants as abutments on the survival of zirconia two-unit anterior cantilever-fixed partial dentures (2U-FPDs) during 10-year simulation. MATERIALS AND METHODS: Human maxillary central incisors were endodontically treated and divided into three groups (n = 24): I, access cavities rebuilt with composite core; II, teeth decoronated and restored with composite; and III as II supported by fiber posts. In group IV, implants with individual zirconia abutments were used. Specimens were restored with zirconia 2U-FPDs and exposed to two sequences of thermal cycling and mechanical loading. STATISTICS: Kaplan-Meier; log-rank tests. RESULTS: During TCML in group I two tooth fractures and two debondings with chipping were found. Solely chippings occurred in groups II (2×), IV (2×), and III (1×). No significant different survival was found for the different abutments (p = 0.085) or FPDs (p = 0.526). Load capability differed significantly between groups I (176 N) and III (670 N), and III and IV (324 N) (p < 0.024). CONCLUSION: Within the limitations of an in vitro study, it can be concluded that zirconia-framework 2U-FPDs on decoronated teeth with/without post showed comparable in vitro reliability as restorations on implants. The results indicated that restorations on teeth with only access cavity perform worse in survival and linear loading. CLINICAL RELEVANCE: Even severe defects do not justify per se a replacement of this particular tooth by a dental implant from load capability point of view.

Influence of the Scalpel Finishing Technique on Marginal Gap Formation in Class II Resin Composite Restorations.

OBJECTIVES: Modern adhesives and composites allow the restoration of deep defects. In such cases, the matrix technique is particularly challenging, and excess composite is a common problem. Removing such overhangs with a scalpel has already been described as a substance preserving or selective finishing technique. Clinically, restoration margins may appear as a white line after scalpel finishing, and it is unclear whether this line represents a marginal gap and/or whether scalpel finishing promotes marginal gap formation. Therefore, the aim of this study was to investigate the influence of scalpel finishing of deep Class II composite restorations on marginal gap formation. METHODS AND MATERIALS: Standardized mesioocclusal-distal (MOD) cavities were prepared and restored in 60 human molars randomly divided into six finishing protocol groups: G1, scalpels (SC); G2, oscillating files (OF); G3, finishing strips (FS); G4, scalpels and finishing strips (SC+FS); G5, scalpels and polishing discs (SC+PD); G6, polishing discs alone (PD, controls). The groups were additionally assigned to finishing and polishing in a phantom head (groups 1-4) or hand-held setting (groups 5-6) to simulate clinical and in-vitro research conditions, respectively. After restoration, artificial aging was performed by thermocycling (5-55°C, 2500 cycles) and mechanical loading (50 newtons (N) with 500,000 cycles) prior to scanning electron microscopy analysis of proximal restoration margin quality on the mesial and distal surfaces (n=120) of each tooth. Outcomes (perfect margin, marginal gap, overhang, marginal fracture) were statistically analyzed by t-test, Mann-Whitney U test, single-factor analysis of variance, post-hoc t-test, Kruskal-Wallis test and Dunn-Bonferroni correction for multiple group comparisons. Cohen's effect size d(Cohen) was calculated to show the strength of the relationship between variables. RESULTS: Overall, marginal quality was significantly better in the hand-held setting (SC+PD and PD) than the phantom head setting (SC, OF, FS, SC+FS). The best marginal quality was achieved with oscillating files in the phantom head setting and with scalpels plus polishing discs in the hand-held setting. Marginal gaps occurred significantly more often with scalpels, but the proportion of gaps was very low and clinically insignificant. Finishing strips were the least effective instruments for removing overhangs but performed better in combination with scalpels. CONCLUSIONS: Scalpel finishing can effectively and gently remove overhangs from enamel. However, blades should be used with caution as they can cut the dentin and cementum. Scalpel finishing does not lead to a clinically relevant increase in marginal gaps, but should be followed by polishing, whenever possible, to eliminate any marginal fractures that might be present.

Loading standardization of postendodontic restorations in vitro: impact of restorative stage, static loading, and dynamic loading.

OBJECTIVE: The load capability of post-restored endodontically treated teeth (ETT) can be determined at different restorative stages. It was the aim of this study to compare the load capability of ETT at these stages. MATERIALS AND METHODS: Maxillary central incisors were divided into 4 groups (n=10) and endodontically treated. Specimens were restored with: (I) only glass fiber posts (GFP); (II) GFP and composite build-up with 2 mm ferrule; (III and IV) with additional adhesively luted all-ceramic crowns. Group (I) to (III) were statically loaded, and group (IV) was exposed to thermomechanical loading (TML) and subsequent static loading. RESULTS: The lowest median load level of 73 N was determined for group (I). The maximum median load value of 331 N was found for group (III). The comparison of Fmax [N] of group (I), (II) and (III) revealed significant differences between the groups (p<0.001). The specimens of group (IV) failed at significantly lower load values (p<0.005) as similarly restored specimens of group (III) which were only statically loaded. The stage of restoration and TML loading prior to static loading had a significant impact on fracture patterns (p=0.006). CONCLUSION: Every additional restorative step torwards a final crown-restored ETT significantly increased the load capability. TML prior to load-to-fracture testing of the complete restorative complex, ie. post, core and crown, significantly decreased maximum load capability.

Caries-inhibiting Effect of Microencapsulated Active Components in Pit and Fissure Sealants.

OBJECTIVE: The aim of the present in vitro study was to examine the caries-inhibiting effect of a pit and fissure sealant (PFS) containing ion-releasing microcapsules under cariogenic conditions in a biofilm artificial mouth. METHODS AND MATERIALS: Forty-eight human third molars were divided into four groups (n=12 per group). Fissures were extended with burs and sealed with experimental PFS. The four groups of specimens were treated as follows: 1) EPFS 1: EPFS (Premier Dental) of increasing viscosity, containing microcapsules loaded with remineralizing agents (calcium, phosphate, and fluoride ions); 2) US: fluoride-releasing PFS (UltraSeal XT plus, UltraDent Products, South Jordan, UT, USA); 3) EPFS 2: experimental PFS of constant viscosity containing microcapsules loaded with calcium, phosphate, and fluoride ions; and 4) FT: glass ionomer cement (GIC) (GC Fuji Triage CAPSULE WHITE glass ionomer cement, GC Europe NV, Leuven, Belgium). FT and US were used as control groups. EPFS 1 and EPFS 2 were the experimental groups. Specimens were stored in distilled water for 14 days at 37°C, subjected to 10,000 thermocycles (5°C and 55°C) and finally exposed to microbiological cycling in a Streptococcus mutans-based artificial mouth for 10 days. Replicas were made for scanning electron microscopic (SEM) evaluation and specimens were cut for fluorescence microscopy. RESULTS: Overall demineralization depths at the margin of Fuji Triage were significantly shallower than in the other groups (p<0.05). Overall demineralization depths adjacent to the experimental pit and fissure sealant EPFS 2 (59±15 µm) were comparable to the values of the resin-based pit and fissure sealant UltraSeal XT plus (58±10 µm, p≥0.05). SEM revealed surface roughness of the GIC-based PFS. CONCLUSIONS: The experimental PFS with microcapsules containing active components for remineralization did not show a caries-inhibiting effect compared to a fluoride-releasing resin-based PFS. Lower demineralization depths adjacent to GIC sealants indicate an anticariogenic effect through fluoride ion release.

Clinical effectiveness of restorative materials for the restoration of carious primary teeth without pulp therapy: a systematic review.

PURPOSE: To systematically search the available evidence and evaluate the clinical effectiveness of restorative materials for restoration of carious primary teeth. The findings aimed to support the European Academy of Paediatric Dentistry (EAPD) guidelines development. METHODS: Literature search was performed by searching 4 electronic databases for eligible randomised controlled clinical trials (RCTs) comparing restorative materials for the restoration of carious primary teeth up to December 28th, 2020. Quality assessment was performed with the revised Cochrane risk-of-bias tool for randomized trials (RoB 2). RESULTS: Of 1685 identified articles 29 RCTs were finally deemed as eligible for inclusion. Annual failure rates were: Amalgam 1-28%; atraumatic restorative treatment 1.2-37.1%; glass-ionomer cement (GIC) 7.6-16.6%, metal-reinforced GIC 29.9%, resin-modified GIC 1.9-16.9%, high-viscosity GIC 2.9-25.6%; glass carbomer ≤ 46.2%; compomer 0-14.7%; composite resin (CR) 0-19.5%, bulk-fill CR 0-16.9%; zirconia crowns 3.3%, composite strip crowns 15%, and preformed metal crowns (Hall-Technique) 3.1%. Secondary caries, poor marginal adaptation, loss of retention, and fracture of restoration were reported as reasons for failure. Four studies were evaluated at unclear and 25 at high risk of bias. Clinical and methodological heterogeneity, and the diversity of tested materials across included studies did not allow for meta-analyses. CONCLUSIONS: Within the limitations of this systematic review, namely, the heterogeneity and the overall high risk of bias among included studies, clear recommendations based on solid evidence for the best restorative approach in primary teeth cannot be drawn. There is a need for future thoroughly implemented RCTs evaluating restorations in primary teeth to close this knowledge gap.

Clinical effectiveness of restorative materials for the restoration of carious lesions in pulp treated primary teeth: a systematic review.

PURPOSE: To systematically review the clinical performance of restorative materials after pulp therapy of carious primary teeth. It is part 2 of a systematic review on the clinical effectiveness of restorative materials for the management of carious primary teeth supporting the European Academy of Paediatric Dentistry (EAPD) guideline development. METHODS: Four electronic databases were systematically searched up to December 28th, 2020. Randomised controlled clinical trials (RCTs) on restorative materials for the restoration of carious primary teeth after pulp therapy were included. Failure rate, annual failure rate (AFR) and reasons for failure were recorded. Studies were sorted by restorative materials. The Cochrane Risk of bias tool for randomised trials (RoB 2.0) was used for quality assessment. RESULTS: After identification of 1685 articles and screening of 41 papers from EAPD review group 1, 5 RCTs were included. Restored primary molars with pulpotomy presented the following AFRs: composite resin (CR) 0%, preformed metal crowns (PMCs) 2.4-2.5%, resin-modified glass-ionomer cement combined with CR 3.8%, compomer 8.9%, and amalgam 14.3%. Maxillary primary incisors receiving pulpectomy exhibited AFRs of 0-2.3% for composite strip crowns (CSCs) depending on the post chosen. Reasons for failure were secondary caries, poor marginal adaptation, loss of retention and fracture of restoration. All studies were classified as high risk of bias. Meta-analyses were not feasible given the clinical/methodological heterogeneity amongst studies. CONCLUSION: Considering any limitations of this review, CR and PMCs can be recommended for primary molars after pulpotomy, and CSCs for primary incisors receiving pulpectomy. However, a need for further well-designed RCTs was observed.

Best clinical practice guidance for treating deep carious lesions in primary teeth: an EAPD policy document.

PURPOSE: The European Academy of Paediatric Dentistry (EAPD) has developed this best clinical practice guidance to help clinicians manage deep carious lesions in primary teeth. METHODS: Three expert groups conducted systematic reviews of the relevant literature. The topics were: (1) conventional techniques (2) Minimal Intervention Dentistry (MID) and (3) materials. Workshops were held during the corresponding EAPD interim seminar in Oslo in April 2021. Several clinical based recommendations and statements were agreed upon, and gaps in our knowledge were identified. RESULTS: There is strong evidence that indirect pulp capping and pulpotomy techniques, and 38% Silver Diamine Fluoride are shown to be effective for the management of caries in the primary dentition. Due to the strict criteria, it is not possible to give clear recommendations on which materials are most appropriate for restoring primary teeth with deep carious lesions. Atraumatic Restorative Technique (ART) is not suitable for multi-surface caries, and Pre-formed Metal Crowns (PMCs) using the Hall technique reduce patient discomfort. GIC and RMGIC seem to be more favourable given the lower annual failure rate compared to HVGIC and MRGIC. Glass carbomer cannot be recommended due to inferior marginal adaptation and fractures. Compomers, hybrid composite resins and bulk-fill composite resins demonstrated similar values for annual failure rates. CONCLUSION: The management of deep carious lesions in primary teeth can be challenging and must consider the patient's compliance, operator skills, materials and costs. There is a clear need to increase the use of MID techniques in managing carious primary teeth as a mainstream rather than a compromise option.

Self-adhesive cements as core build-ups for one-stage post-endodontic restorations?

AIM: To investigate the load capability of root filled teeth restored with glass fibre posts when the same self-adhesive composite resin cement was used as post cement and core build-up material. METHODOLOGY: Human maxillary central incisors were divided into four groups (n=10). Teeth were root filled, decoronated and restored using glass fibre posts luted with different cements and composite resins for core build-up (i) RelyX Unicem/Clearfil Core (RXU/CC), (ii) RelyX Unicem/ RelyX Unicem (RXU/RXU), (iii) RelyX Unicem/LuxaCore-Dual (RXU/LCD) and (iv) LuxaCore-Dual/Clearfil (LCD/CC). A 2-mm ferrule crown preparation was always performed. All specimens were restored with adhesively luted all-ceramic crowns and were exposed to thermal cycling and mechanical loading (TCML) and subsequently statically loaded. For analysis of cycles-to-failure during TCML, log-rank statistics were calculated. The nonparametric Kruskal-Wallis test was applied to study group mean differences. Differences in the frequency of the failure modes between the groups were evaluated by Fisher's exact test. All tests were two-sided (α=0.05). RESULTS: Three specimens of RXU/LCD and two of RXU/RXU and LCD/CC, respectively, failed during TCML (P=0.379). For these specimens, the load capability value was set at 0 N. The median fracture load values (min/max) in (N) were RXU/CC=294 (209/445), RXU/RXU = 166 (0/726), RXU/LCD=241 (0/289) and LCD/CC=200 (0/371) (P=0.091). The RXU/CC had the highest (80%) and RXU/LCD the lowest (20%) percentage of restorable failures (P=0.028). CONCLUSIONS: These results imply that self-adhesive composite achieved similar load capabilities when used as core build-up materials in root filled teeth restored with glass fibre posts and all-ceramic crowns.

Prevalence and association of headaches, temporomandibular joint disorders, and occlusal interferences.

STATEMENT OF PROBLEM: Although an interaction of malocclusion, parafunction, and temporomandibular joint disorders (TMD) can be inferred from the experience of daily practice, scientific evidence to corroborate this hypothesis does not exist. However, there are indications that TMD and headaches may be intertwined. PURPOSE: The purpose of this study was to identify the presence or absence of an association of occlusal interferences, parafunction, TMD, or physiologic, muscular, or prosthodontic factors with the occurrence of headache. MATERIAL AND METHODS: In a private practice population of 1031 subjects (436 men and 595 women, mean age 49.6 years) the demographic parameters, headache and general pain history, habits and general personal information were recorded. Clinical examination for dental, muscular, and temporomandibular joint pathology was accomplished. Data were statistically analyzed using the Mann-Whitney U, Kruskal-Wallis, and Chi-Square tests (α = .05). A multinomial logistic regression analysis was performed with respect to confounding variables. RESULTS: Headache affliction was found to affect women more frequently than men (1.7:1). Students and non academics were more prone to suffer from headache. Parafunction (P=.001), TMD (P=.001) and gross differences between centric occlusion and maximum intercuspation of more than a 3 mm visible track marked with 8 µm articulation foil (P=.001) significantly influenced the presence of headache. Headache intensity and frequency decreased with age. While tension-type headache was most frequently diagnosed, the parameters studied were not significantly associated with one certain headache diagnosis more frequently than others. CONCLUSIONS: Stomatognathic factors of TMD, parafunction, and gross differences between centric occlusion and maximum intercuspation of more than 3 mm are associated with headache. These findings should be interpreted with caution due to the cross-sectional nature of this study.

Clinical and radiographic success of (partial) pulpotomy and pulpectomy in primary teeth: A systematic review.

AIM: The aim of this systematic review was to evaluate the clinical outcome of partial pulpotomy, pulpotomy and pulpectomy for treating primary teeth with normal or infected pulp or with irreversible pulpitis. METHODS: Two reviewers on Pubmed and ISI Web of Science performed a comprehensive literature review of publications from 1966 until July 2019. Pico outline was used to facilitate literature research. Among abstracts, publications were selected according to the following criteria: prospective clinical study, correct indication for the performed treatment, clear definition of clinical and/or radiographic success criteria and at least 6-month follow-up period. The strict selection criteria under the keywords "pulpotomy", "partial pulpotomy" and "pulpectomy" resulted in a limited amount of randomised controlled trials (RCT) or controlled clinical trials (CT). Qualitative assessment of the selected clinical studies and level of evidence was included according to the criteria described by the Oxford Centre for Evidence-Based Medicine (CEBM). CONCLUSION: Prerequisites for a successful pulpotomy are symptom-free teeth, sterile removal of coronal pulp and haemostasis. Both MTA and formocresol perform well for partial pulpotomies after caries exposure. Formocresol had been the most popular amputation material for pulpotomies. Due to the potential side effects, other medicaments, such as ferric sulfate, mineral trioxide aggregate (MTA) or NaOCl are suggested. Grey and white MTA yeld the same results. Lasers are not recommended due to their large diversity. Regarding pulpectomy, the conditions, procedures, and evaluation for the treatment were not well defined in the studies. Nevertheless, there is evidence to use calcium hydroxide, zinc oxide eugenol paste or iodoform based pastes as root filling materials for non-vital molars. Pulpectomies showed better success rates than pulpotomies. Stainless steel crowns are recommended as definite restorations after both endodontic treatments. Longer follow-up periods, further clinical studies with comparable conditions and clear definition of evaluation criteria are needed to further confirm the results of endodontic treatment in primary teeth.

The effect of different liners on the bond strength of a compomer to primary teeth dentine: in vitro study.

OBJECTIVE: This in vitro investigation should identify the effect of protective liners on dentine bond strength of a polyacid modified resin composite to dentine of primary teeth. METHODS: Forty-two extracted caries-free primary molars were randomly assigned to seven groups (n = 6) and flattened. Six test groups were centrally covered with different protective liners/base materials: Kerr Life (KL), IRM zinc oxide eugenol cement (IRM), Ketac Bond (KB), Vitrebond (VB), Dycal (DY), and mineral trioxide aggregate (MTA). Specimens were bonded with Prime&Bond NT (PB) and restored with Dyract eXtra. The control group (C) did not receive liner pretreatment. After 24-h storage in Aqua dest. (37 °C), specimens were cut and regional microtensile bond strengths of the uncovered areas were tested. Fractography was conducted under a light microscope and further interface/surface analyses were performed under a SEM. Statistical appraisal was carried out using oneway ANOVA (mod. LSD test; p < 0.05). RESULTS: Independent of the distance to the applied liner, all groups exhibited inferior µ-TBS to dentine of primary teeth compared to the control group (p < 0.05). The results were as follows in MPa(SD) x:significance level/percentage of adhesive fractures: PB: 34 (10)A/72%; KL: 23 (25)B/64%; KB: 15 (12)C/76%; DY 15 (13)C/55%; IRM: 14 (10)C/68%; VB: 12 (10)C/61%; MTA 12 (10)C/69%. CONCLUSIONS: Protective liners significantly reduced µ-TBS to dentine of primary teeth.

Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments.

AIM: To assess the efficacy of removing Activ GP or GuttaFlow from canals using NiTi instruments. METHODOLOGY: Root canals in 55 extracted pre-molars were prepared to apical size 40, 0.04 taper. The teeth were imaged with micro-CT, and 30 teeth selected that had consistent apical size and taper of the shaped canals. They were randomly assigned to root filling with either the glass-ionomer-based ActivGP system (n = 15) or the polyvinylsiloxane-based GuttaFlow system (n = 15). After 2 weeks, canals were retreated stepwise with size 40-50 EndoSequence 0.04 taper instruments. Micro-CT scans (8 mum) were taken after use of each instrument to detect root filling residue in the coronal, middle and apical segment, and the retreatment time recorded. Residue, expressed as percentage of canal surface area, was compared between groups with t-tests, and within groups with repeated measures anova and Bonferroni-adjusted pairwise comparisons. Retreatment time was analysed with one-way anova. RESULTS: The percentage of sealer residue-coated canal surface was consistently highest (P < 0.001) in the apical third of canals, and it did not differ significantly between the two root filling groups. Stepwise enlargement from size 40 to 50 significantly decreased the amount of sealer residue in both groups (P < 0.001). Retreatment time did not differ significantly between groups. CONCLUSIONS: Both root fillings with ActivGP and GuttaFlow were removed with nickel-titanium rotary instruments. Enlargement of canals up to two sizes beyond the pre-retreatment size was necessary to minimize the amount of sealer remaining.

Effectiveness of four electronic apex locators to determine distance from the apical foramen.

AIM: To evaluate the accuracy of four electronic apex locators (EAL) in the apical region (0-3 mm short of the foramen) and to compare the precision of the readings on the display with the real position of the file in the root canal. METHODOLOGY: Twenty single-rooted extracted teeth with round root canals were used. The canal orifices were preflared, and the length to the major foramen was determined visually under a microscope. Canals were enlarged, so that a size 15 file fitted well inside the canal. Teeth were mounted in acrylic test tubes filled with physiologic saline solution. Electronic length was determined in the region between the major foramen and 3 mm short of it in 0.5 mm steps with the Dentaport ZX, Root ZX mini, Elements Diagnostic Unit and Apex Locator and Raypex 5 using files of size 10 and size 15. The data were analysed using linear regression between true length and EAL reading, Bland-Altman plots and nonparametric tests at a significance level of alpha = 0.05. RESULTS: The major foramen was detected by all EALs. With a measurement file positioned directly at the major foramen, meter readings were equivalent to a position 0.01-0.38 mm away. For the Dentaport ZX, a better accuracy using the size 15 file for the area 0-1.5 mm short of the apex was found. The differences in measurements between the two files were smaller for the other EALs. In linear regression, a good linearity for Dentaport ZX and Root ZX mini and moderate linearity for Elements Diagnostic Unit and Apex Locator and Raypex 5 were found. The slope of the measurement curve was too low (0.37-0.57) for the Raypex 5 and almost optimal for the Dentaport ZX (1.01-1.05). The Root ZX mini and the Elements Obturation Unit produced lower slope values and especially the Elements Obturation Unit revealed much higher SDs at the different measurement levels. CONCLUSION: Amongst the four EALs, the Dentaport ZX and Root ZX mini had the best agreement between true lengths and meter readings. For the Raypex 5, an interpretation of the colour-coded zones as distance to the foramen cannot be recommended and might lead to erroneous interpretations.

Guidelines for the preparation of CAD/CAM ceramic inlays and partial crowns.

Ceramic inlays and partial crowns have become scientifically recognized posterior restorations. Their clinical effectiveness depends on the development of durable dental ceramics and luting materials as well as an effective bonding system. Therefore, these factors were in the focus of interest in the past. In contrast, only little attention was given to preparation techniques. However, current studies show that special preparation rules should be followed to ensure best fitting CAD/CAM ceramic restorations and long-lasting clinical success. This paper describes preparation requirements by means of detailed three-dimensional schematic drawings and then deduces the clinical procedure for the preparation of ceramic inlays and partial crowns with standardized preparation instruments.

Relative effectiveness of direct and indirect pulp capping in the primary dentition.

INTRODUCTION: Carious or traumatised teeth with a normal pulp status or with reversible pulpitis need an indirect or direct pulp capping procedure to keep the pulp vital. AIM: To evaluate the clinical outcome of both interventions for treating vital primary teeth. STUDY DESIGN: Two reviewers on Pubmed and ISI Web of Science performed a comprehensive literature review of publications from 1966 until December 2017. Among PubMed abstracts, publications were selected according to the following criteria: prospective clinical study, correct indication for the performed treatment, and clear definition of clinical and/or radiographic success criteria. The strict selection criteria limited the amount of randomised controlled trials (RCT) or controlled clinical trials (CT); especially for "indirect pulp therapy", "direct pulp capping" and the number of RCTs was limited. CONCLUSIONS: Based on a systematic review (20 controlled clinical studies or randomised controlled clinical studies), the following statements can be given: Due to the opportunity of tissue repair, indirect pulp treatment can be an acceptable procedure for reversible pulp inflammation. The use of adhesives for indirect pulp capping in a single-visit procedure after gentle caries removal can be recommended. Successful pulp capping is possible under defined conditions (symptom-free tooth, disinfection of pulp exposures, Class-I cavity) and appropriate sealing of the cavity with an effective dentine seal being a conditio sine qua non. There is maximum evidence for the use of disinfecting solutions prior to pulp capping and Dycal as pulp capping material. Longer follow-up periods, more clinical studies, comparable conditions, and clear definitions of evaluation criteria are needed to confirm the results of endodontic treatment in primary teeth.

[Study of biomimetic apatite formation on dentine surface].

The aim of this study was investigation of the opportunity of biomimetic growth of apatite on a dentine surface at various methods of its processing. Artificial blood human plasma--simulated body fluid (SBF)--was used as a source of ions. According to the scanning electronic microscope (SEM) and confocal laser scanning microscope (CLSM) and energy dispersive X-ray analysis (EDX) they have revealed the growth of crystals of calcium--deficient apatite. The structure of the formed apatite layer differed depending on a kind of processing of a dentine surface. After acid etching the globules of the apatite are located chaotically and the part of a dentine surface remains free. The removal of the collagen fibres by NaClO promotes uniform, controllable growth of crystals, forming a monolithic layer. The hypermineralisated areas of a tooth create the best conditions for growth. The transformation hydroxyl apatite in a superficial dentine layer can be caused by increasing of pressure at preparing with diamond bur. The growth of crystals of brushite in the smear layer is possible at a storage in water at 37 degrees capital ES, Cyrillic. The crystals have lamellar form and are well integrated in a dentin surface.