Enamel Dentin Research Articles

Electrosurgical Adjunct for Soft Tissue Management of the Paediatric Dental Trauma Patient

The interface between dental restorations and the neighbouring soft tissue is of key significance for restorative success and longevity. Trauma-related enamel–dentine fractures are frequently present with the restorative challenge of subgingival margins and little remaining tooth structure. This report looks at two paediatric dental trauma patients with extensive crown fractures resulting in subgingival margins, which posed a poor long-term tooth survival. Electrosurgery was used before definitive composite restorations to allow for supragingival margins and access. Each patient attended the Child Dental Health Department at the University of Manchester Dental Hospital for assessment and treatment provision. CPD/Clinical Relevance: This article identifies electrosurgery as an increasingly useful adjunct to restorative management of traumatized permanent incisor teeth in paediatric patients.

Dentin Grafts: Navigating the Paradigm Shift in Regenerative Dentistry.

The biomaterial of dentin has emerged as a promising candidate for the tissue engineering of dental hard tissues. In bone tissue engineering, it may serve as either a scaffold or a reservoir of growth factors. The physical and chemical similarities between the dentin structure and bone have sparked scientific interest in using its features for the development of a new bone transplant material. Dentin, unlike hard and fragile enamel, is viscoelastic, making it a very effective bone replacement. The regeneration of pulp tissue has proven challenging due to its encasement in dentin, which lacks collateral blood flow except from the apical end of the root. Yet, the emergence of contemporary tissue engineering and the identification of dental stem cells have enabled experimentation with the regeneration of both pulp and dentin. This review will explain the different types of dentin grafts, their biocompatibility, safety, and effectiveness, along with difficulties. Additionally, the paper covers several strategies for creating autogenous dentin grafts and gives evidence-based insights into their clinical effectiveness. Overall, dentin grafts appear as a potential alternative to standard graft materials, stimulating tissue regeneration and enhancing patient outcomes in regenerative dentistry operations.

Molar enamel–dentine junction shape of Pliobates cataloniae and other Iberian pliopithecoids

The phylogenetic relationships of the small-bodied catarrhine Pliobates cataloniae (∼11.6 Ma, NE Iberian Peninsula) have been controversial since its original description. However, the recent report of additional dentognathic remains has supported its crouzeliid pliopithecoid status. Based on the available hypodigm, the molar enamel–dentine junction (EDJ) shape of P. cataloniae is compared with that of other pliopithecoids from the same basin as well as both extinct and extant hominoids to further evaluate its pliopithecoid affinities. We also quantitatively compare the EDJ shape among these taxa by means of landmark-based three-dimensional geometric morphometrics using principal component analysis (PCA), canonical variate analysis, and between-group PCA. Permutation tests are performed to test whether Pliobates variation exceeds that of extant hominoid genera. Results indicate that Pliobates is similar in molar EDJ shape to other pliopithecoids, particularly crouzeliids. The variation displayed by Pliobates upper molars is less marked at the EDJ level than at the outer enamel surface, probably owing to differential enamel wear and intraspecific differences in enamel thickness. Multivariate analyses of EDJ shape show that all pliopithecoids (including Pliobates) cluster together in the PCAs, canonical variate analyses, and between-group PCAs and occupy a different portion of the morphospaces from extinct and extant hominoids. Posterior and typicality probabilities strongly support the classification of Pliobates as a pliopithecoid, wheras permutation tests fail to reject the single-genus hypothesis for the P. cataloniae hypodigm. We conclude that P. cataloniae is a crouzeliid pliopithecoid, as recently supported by cladistic analyses of craniodental characters, and that previous cladistic results that supported a stem hominoid status are attributable to postcranial convergences with crown hominoids. Our results further highlight the potential of three-dimensional geometric morphometrics analyses of the EDJ shape for better informing fossil primate alpha-taxonomy by means of quantitatively testing hypotheses about tooth shape variation.

Early ray‐finned herbivores: the dental system of Eurynotoidiidae (Actinopterygii; middle–late Permian, European Russia) and implications for palaeobiology and palaeoecology

AbstractEurynotoidiformes are a little‐known group of actinopterygian fishes from the Permian of European Russia, characterized by the possession of multicuspid marginal teeth arranged in a single row. Morphologically, the teeth resemble those of Recent Cichlidae, Acanthuridae, Siganidae or Serrasalmidae, suggesting similar trophic adaptations related to herbivory. Tooth histology is similar to the majority of basal actinopterygians (composed of dentine, acrodin and collar enamel). Teeth are ankylosed in their attachment, and labial pleurodont in implantation, strengthening the tooth. The multicuspid tooth crowns derive from conical teeth of predatory or omnivorous ancestors, analogous to the evolution of multicuspid teeth in cichlid fishes. Tooth replacement in eurynotoidiforms is most comparable to an alternating pattern, with a possible simultaneous, unilateral replacement occurring in the whole jaw, similar to characiform fishes. Replacement teeth were formed extraosseously. Teeth of the inner dental arcade were conical. Based on comparisons with the teeth of extant actinopterygians specialized for herbivory, along with functional morphological analysis and consideration of wear patterns, we hypothesize that eurynotoidiforms represent the oldest known actinopterygians specialized for herbivory. Several strategies of herbivory in Recent actinopterygians were already realized by eurynotoidiforms as early as the Late Palaeozoic (middle and late Permian): grazing/cutting filamentous algae (Lapkosubia spp., Isadia suchonensis), browsing/biting off macrophyte fragments (Isadia aristoviensis), scraping/harvesting periphyton from hard substrates (Isadia opokiensis, I. arefievi). However, notable morphological differences in the jaws (elongate) and tooth arrangement (homodont along the jaw, functional teeth separated) suggest that this Permian experiment in herbivory followed different pathways compared to extant taxa.

Traumatize anterior teeth, dento-facial anomalies among deaf person in the middle region of Iraq

This study was designed to determine the type and prevalence of trumatic dentalinjuries, aenterio—posterior molar relation among (519) deaf persons and (532) schoolstudents at 5-16 years of age in the middle region of Iraq. The study showed that theprevalence of traumatic dental injuries were 6.94% for deaf persons and 5.83% forschools students. Males showed a higher percentage of traumatized teeth than females ininstitutions and school students. Enamel dentine fracture without pulp exposure was themost predominant type among deaf persons while simple enamel fracture was the mostpredominant among schools students. The majority of deaf persons and schools studentsdemonstrated normal type of occlusion 57.42%, 55.64% respectively. Deaf personshowed significantly with percentage of 4.62% mesial full cusp deviation from normal.antero·postrior molar relation compared to school students 2.07%

Characterizing the microstructures of mammalian enamel by synchrotron phase contrast microCT

The enamel of mammalian teeth is a highly mineralized tissue that must endure a lifetime of cyclic contact and is inspiring the development of next-generation engineering materials. Attempts to implement enamel-inspired structures in synthetic materials have had limited success, largely due to the absence of a detailed understanding of its microstructure. The present work used synchrotron phase-contrast microCT imaging to evaluate the three-dimensional microstructure of enamel from four mammals including Lion, Gray Wolf, Snow Leopard, and Black Bear. Quantitative results of image analysis revealed that the decussation pattern of enamel consists of discrete diazone (D) and parazone (P) bands of rods organized with stacking arrangement of D+/P/D-/P in all mammals evaluated; the D+ and D- refer to distinct diazone bands with juxtaposed rod orientations from the reference plane. Furthermore, the rod orientations in the bands can be described in terms of two principal angles, defined here as the pitch and yaw. While the pitch angle increases from the outer enamel to a maximum (up to ≈ 40°) near the dentin enamel junction, minimal spatial variations are observed in yaw across the enamel thickness. There are clear differences in the decussation parameters of enamel across species that are interpreted here with respect to the structural demands placed on their teeth. The rod pitch and band width of enamel are identified as important design parameters and appear to be correlated with the bite force quotient of the four mammals evaluated. Statement of significanceThe multi-functionality of tooth enamel requires both hardness and resistance to fracture, properties that are generally mutually exclusive. Ubiquitous to all mammalian teeth, the enamel is expected to have undergone adaptations in microstructure to accommodate the differences in diet, body size and bite force across animals. For the first time, we compare the complex three-dimensional microstructure of enamel from teeth of multiple mammalian species using synchrotron micro-computed tomography. The findings provide new understanding of the “design” of mammalian enamel microstructures, as well as how specific parameters associated with the decussation of rods appear to be engineered to modulate its fracture resistance.

Effects of Different Types of Periodontitis on CBCT Morphology of Dental Tissue in Two Ethnic Groups

For the periodontitis patients who came to our hospital from October 2021 till now, the influence of different types of periodontitis on the CBCT morphology of dental tissue of different nationalities was analyzed. To measure the distance between the enamel dentin boundary and root fork of the mandibular first molar, the thickness of the crown hard tissue above the mesial pulp Angle, the thickness of the crown hard tissue above the distal pulp Angle, the height of the pulp chamber, the volume and surface area of the pulp, so as to provide a certain basis for the possibility of future dental tissue lesions.

Stereolithography-manufactured zirconia substrate with bionic-patterned surface microstructure for enhancing bond strength to porcelain veneer

The bond strength between the zirconia substrates and porcelain materials has been extensively investigated, and sandblasting is one of the most effective methods for increasing the bond strength between zirconia and porcelain. However, it also introduces microcracks and pollution, which have a negative impact on the final mechanical properties of zirconia restorations. To increase the mechanical chimaerism of zirconia/veneer structures nondestructively, in this study we developed a novel surface design called a bionic-patterned surface microstructure (BSM) using stereolithography (SLA) technology. Inspired by the dentin–enamel junction model, the microstructure includes a cylinder and pit. Among all the specimens, both computer numerical control (CNC) zirconia with sandblasting and SLA zirconia with BSM showed higher bond strengths than the CNC group (P < 0.001), and the BSM groups showed improved bonding properties (P < 0.001). No significant differences were observed between the cylindrical and pit BSM at the same height/depth (P = 0.493), and for BSM of the same type, the bond strength increased with increasing height/depth (P < 0.001). Zirconia with BSM thus had superior bond strength to porcelain veneers. The height/depth of the BSM had a positive effect on the bonding strength, whereas the type had no effect.

Masking discolored substrates with resin composites: effect of layering strategies.

This study aimed to evaluate the masking ability of different resin composite (RC) layering techniques over discolored substrates. Layering strategies were tested (n=10), using different RCs: flowable opaque, white dentin, A1 dentin, A1 body, and A1 enamel (Filtek Z350XT; 3M ESPE). Bilayer and trilayer RC combinations resulted in final thicknesses of 1 mm, 1.5 mm, and 2 mm. Substrates tested were: A1 (reference), A3, A4, B3, C2, and C4 (Filtek Z350XT Dentin; 3M ESPE). Color differences (∆E00) were measured for the RC layers over discolored substrates with the CIEDE2000 formula. The results were compared statistically (One-way ANOVA) and descriptively (acceptability=1.77 and perceptibility=0.81 thresholds). The layering strategy influenced the ∆E00 of RCs over all substrates (P<0.001). The 1 mm bilayer group combining 0.5 mm of dentin and 0.5 mm of enamel led to ∆E00 below AT for substrates A3 and B3; the 1.5 mm bilayer group combining A1 dentin (1 mm) and enamel (0.5 mm) provided ∆E00 below AT for substrates A3, A4, and C2 and ∆E00 below PT for B3; for substrate C4, the 2 mm trilayer group combining flowable opaque (0.2 mm), A1 dentin (1.3 mm) and enamel (0.5 mm) provided ∆E00 below PT, and the 1.5 mm trilayer groups (flowable opaque + 0.8 mm dentin or body + enamel) led to ∆E00 below AT. Resin Composites were effective in masking discolored substrates. The most adequate layering strategy depended on substrate shade.

Evaluation of antimicrobial photodynamic therapy and minimal intervention associated with deproteinisation in permanent teeth with molar incisor hypomineralisation: study protocol for a clinical, controlled, blinded trial

IntroductionMolar incisor hypomineralisation (MIH) is a qualitative defect of enamel development that occurs in the mineralisation phase. MIH affects one or more permanent molars and, occasionally, permanent incisors. The aim...

Traumatic dental injuries over an 8-year period at a German dental center: a retrospective overview and cross-sectional analysis.

The aim of this study was to analyze a population of patients who had suffered from traumatic dental injuries (TDIs) by using different patient-, trauma- and treatment-related parameters. All dental records of patients ≥ 3years old who had presented at the dental emergency service between Jan 1, 2009 and Dec 31, 2016 for the treatment of dental trauma were analyzed. A total of 2758 patients were invited for a recall examination at the Department for Dental Surgery and Implantology, ZZMK Carolinum, Goethe University Frankfurt, Germany; of these, 269 patients attended their recall appointments. The enrolled patient population consisted of 1718 males and 1040 females, with a mean age of 19.63years (median 12.00 ± 17.354years). A total of 4909 injured teeth were assessed, with a mean of 1.78 injured teeth per patient (median 2.00 ± 1.279). Males were found to be more frequently affected by TDIs compared to females (1.65:1). The majority of these injuries occurred in the first two decades of life (66.1%; n = 1824). The majority of the patients presented for initial treatment within 24h of their accident (95.7%). The most frequent TDIs were isolated luxation injuries 49.4% (n = 2426) and isolated crown fractures 30% (n = 1472). Combination injuries were diagnosed in 20.6% of the cases (n = 1011). Based on the findings of the present analysis, it can be concluded that males were more frequently affected by TDIs than females. Most patients had suffered from TDI before they had turned 10years of age. Overall, the enamel-dentin fracture was found to be the most frequent injury, followed by concussions and lateral luxations.

Pre-eruptive intracoronal resorption: case report

This case describes the presentation of pre-eruptive intracoronal resorption affecting multiple permanent teeth in an 11-year-old female child. Pre-eruptive intracoronal resorption is a lesion that is often located within the dentine, adjacent to the enamel–dentine junction in the occlusal face of the tooth crown. Histological reports have shown the presence of resorptive cells in these lesions. Previous literature presents cases usually affecting a single tooth, in this case 10 permanent teeth were found to be affected. Clinicians should be aware of this diagnosis and its treatment modalities to ensure appropriate management is carried out. CPD/Clinical Relevance: This case highlights pre-eruptive intracoronal resorption for clinicians based in both primary and secondary care settings

Remineralizing potential of the biomimetic P11-4 self-assembling peptide on noncavitated caries lesions: A retrospective cohort study evaluating semistandardized before-and-after radiographs

BackgroundSelf-assembling peptide (SAP) P11-4 was introduced to treat initial caries lesions by means of guiding hydroxyapatite regeneration within the lesion. The objective of this study was to assess its effectiveness in a practical clinical setting. MethodsCaries lesions in permanent teeth treated with monomeric and polymeric SAP P11-4 from May 2015 through October 2020 were retrospectively analyzed at lesion and child levels by means of bite-wing radiography for changes in stage and cavitation and restoration. ResultsTwo hundred and nineteen children aged 10 through 19 years with a total of 405 proximal lesions in posterior teeth were followed from 0.4 through 5.5 years (median, 7 months; interquartile range, 6-19 months). Regression occurred in 37% of stage RA1 (radiolucency in the outer one-half of enamel) (95% CI, 31% to 44%), 38% of stage RA2 (radiolucency in the inner one-half of enamel plus or minus the enamel–dentin junction) (95% CI, 30% to 45%), and 40% of stage RA3 (radiolucency limited to the outer one-third of dentin) (95% CI, 16% to 68%) lesions. The proportion of lesions with no cavitation was 0.96 (95% CI, 0.94 to 0.98) after 1 year and 0.91 (95% CI, 0.88 to 0.95) after 2 years. ConclusionsReal-world clinical data indicate that SAP P11-4 can lead to recovery and a healthier tooth stage. Practical ImplicationsSAP P11-4 is a safe treatment for initial caries lesions in permanent teeth that remineralizes in the deepest zone of the lesion and can be introduced easily into routine dental practice.

Биохимическое и морфологическое обоснование соединительнотканной гипотезы прорезывания нижних третьих моляров

Studying the mechanism underlying tooth eruption is an important and promising area due to the increased incidence of the diseases associated with tooth eruption abnormalities or difficulties that can result in purulent and septic complications. The study was aimed to explore variability and structural features of the hard tissue mineral component and organic matrix in mandibular third molars being at different stages of tooth eruption. Microscopic examination and biochemical testing of the enamel, dentin, and dentin–enamel junction of the study participants’ (n = 67; females aged 14–36) mandibular third molars were performed by scanning electron microscopy and Fourier transform infrared (FT-IR) spectroscopy. The association of the tooth eruption stage with the hard tissue structural features, such as the degree of mineralization and the size of dentinal tubules, orientation and size of the enamel prisms, was revealed. There were significant differences in the mandibular third molar hard tissue water content, which was demonstrated by metabolic processes and maturation rate (p &lt; 0.05). According to the IR spectroscopy data, intensity of the collagen absorption bands in the enamel increases with age, while in dentin it decreases (1202, 1249, and 1342 cm–1). Furthermore the combination of the reduced intensity of the 1202 cm–1 band with the increase in the 1342 cm–1 dentin–enamel junction band confirms the important role it plays as a link between the enamel and dentin due to its metabolic, shock-absorbing, protective, and nutritional functions. The findings demonstrate significant changes in the wrapping and orientation of the collagen fibrils and fibers in the hard tissue, which affect primary spatial orientation and mandibular dental topography.

Noninvasive diagnostic method using optical coherence tomography detected a vulnerable dentin enamel junction created by phosphoric acid etching.

To investigate the influence of phosphoric acid etching on the dentin enamel junction (DEJ) using optical coherence tomography (OCT). Human teeth were assigned to four groups: 1. control, no additional treatment (CT); 2. The primer of "SE Bond2" was applied (SE), 3. "Enamel Conditioner" was applied (EC), 4. "K-etchant syringe" was applied (KE). After treatment, the DEJ was observed using a laser microscope (CLSM), OCT, and scanning electron microscopy (SEM). Additionally, an ultimate tensile strength (UTS) test at the DEJ was performed. No cracks were observed by CLSM. In contrast, cracks were observed all samples by SEM. Additionally, OCT revealed a white line along the DEJ in all KE specimens and some EC specimens. The UTS test showed a significant difference between CT and KE. This study found that phosphoric acid etching may cause excessive demineralization and weaken the DEJ. This fragility was observed using a non-invasive diagnostic method using OCT.

Thermal Properties of Selected Group of Dental Materials

The thermal properties of dentine and tooth enamel affects the rate of response of the tooth nervous system to the temperature changes to which the tooth is exposed on a daily basis. Today almost all manufacturers of dental materials in their certificates of material quality describe material chemical composition, mechanical properties, process ability and aesthetic characteristics, while information about thermal properties (thermal conductivity, thermal capacity and temperature diffusivity) are not available. Within the interdisciplinary teamwork, thermal properties of five selected dental materials were measured and analyzed by modern Transient Plane Source (TPS) method in accordance with the standard ISO 22007-2. Thermal properties were measured at temperature interval between 0°C and 50°C.

Exploring prenatal and neonatal life history through dental histology in infants from the Phoenician necropolis of Motya (7th–6th century BCE)

The biological life history of infants from archaeological contexts can provide a unique insight into past human populations. Dental mineralized tissues contain a permanent record of their growth that can provide access to the prenatal and early infant life, and mortality, of human skeletons. This study focuses on the histomorphometric analysis of deciduous teeth from the ‘Archaic Necropolis’ of Motya (7th–6th century BCE, Sicily–Italy). The histomorphometric analysis is conducted on prenatal and postnatal enamel of eight anterior deciduous teeth from seven individuals from this Phoenician population to estimate their chronological age-at-death, health, and enamel growth parameters. Proteomic analysis has been used to determine the sex of the infants.The presence of the Neonatal Line in all specimens indicates that the seven individuals survived birth. The occurrence of at least one Accentuated Line in prenatal enamel in four out of seven individuals suggests the foetuses and/or their mothers experienced a stress-related event during pregnancy. As expected, there was limited variation in Daily Secretion Rates near the Enamel Dentine Junction. These rates increase toward the outer enamel surface and decrease toward the cervix.Our findings illustrate the importance of dental histology for reconstructing perinatal and early infancy mortality and morbidity patterns at Motya, which sheds light on the socio-cultural perception of new-borns and infants in an ancient Phoenician community.

Infrared Spectroscopy to Analyze Sexual Dimorphism of Hard Dental Tissue Maturation at Eruption in Patients with Connective Tissue Dysplasia.

The aim of this study was to research the biochemical changes in the hard tissues of the lower "wisdom" teeth, which are at the stage of eruption, with connective tissue dysplasia, depending on sex. The study involved 38 patients aged 17-25 years, who had the extraction of the lower third molars on the left and right for medical reasons. Twenty-one participants in the experiment (16 females, five males) were diagnosed with connective tissue dysplasia; the remaining 17 were healthy and made up the control group (11 females, six males). Samples of enamel, dentin, and enamel-dentin junction were dried to constant weight and examined in tablets pressed in a mixture with potassium bromide on an FT-801 Fourier transform infrared (FT-IR) spectrometer (NPF Simex, Russia) in the range of 500-4000 cm-1. In the IR spectra of the enamel, enamel-dentin junction, and dentin, the absorbance ratio of amide I and II changed significantly and the absorbance of the absorption band of phosphate ions decreased from enamel to dentin. Differences between groups with and without connective tissue dysplasia increased in the following series: dentin, enamel-dentin junction, and enamel. With connective tissue dysplasia, a change in the ratio of the intensities of the absorption bands of amide I and phosphate ions was observed. Normally, the content of organic substances in the enamel of the teeth in the males group is lower than in the females group. Against the background of connective tissue dysplasia, the content of organic substances in the enamel in women decreased while in men it increased, which confirmed the presence of sexual dimorphism during the maturation of hard dental tissues at the eruption stage. The study confirms the opinion of many researchers about the significant role of collagen proteins, which, together with non-collagen proteins, are involved in the development and maturation of dental hard tissues, which are characterized by pronounced heterogeneity and sexual dimorphism in the group with connective tissue dysplasia.

Deep dental phenotyping and a novel FAM20A variant in patients with amelogenesis imperfecta type IG.

To identify etiologic variants and perform deep dental phenotyping in patients with amelogenesis imperfecta (AI). Three patients of two unrelated families were evaluated. Genetic variants were investigated by exome and Sanger sequencing. An unerupted permanent third molar (AI1) from Patient1 and a deciduous first molar (AI2) from Patient2, along with three tooth-type matched controls for each were characterized. All three patients harbored biallelic pathogenic variants in FAM20A, indicating AI1G. Of the four identified variants, one, c.1231C > T p.(Arg411Trp), was novel. Patient1 possessed the largest deletion, 7531 bp, ever identified in FAM20A. In addition to hypoplastic enamel, multiple impacted teeth, intrapulpal calcification, pericoronal radiolucencies, malocclusion, and periodontal infections were found in all three patients, gingival hyperplasia in Patient1 and Patient2, and alveolar bone exostosis in Patient3. Surface roughness was increased in AI1 but decreased in AI2. Decreased enamel mineral density, hardness, and elastic modulus were observed in AI1 enamel and dentin and AI2 dentin, along with decreased phosphorus, increased carbon, and increased calcium/phosphorus and carbon/oxygen ratios. Severely collapsed enamel rods and disorganized dentin-enamel junction were observed. We report a novel FAM20A variant and, for the first time, the defective mineral composition and physical/mechanical properties of AI1G teeth.

Pulp chamber temperature rise in light-cure bonding of brackets with and without primer, in intact versus restored teeth.

To evaluate the pulp chamber temperature rise (PCTR) in light-cure bonding of brackets with and without primer, in intact and restored mandibular central incisors (M1), maxillary first premolars (Mx4), and mandibular third molars (M8). Ninety human teeth were included: M1 (n=30), Mx4 (n=30), and M8 (n=30). Light-cure bonding of brackets was performed in intact (n=60) and restored (n=30) teeth, with primer (n=60) or without (n=30) primer. PCTR was defined as the difference between initial (T0) and peak temperatures (T1), recorded with a thermocouple during light-cure bonding. Differences on PCTR between bonding techniques (primer vs. no primer), teeth types (M1 vs. Mx4 vs. M8), and teeth condition (intact vs. restored) were estimated by ANCOVA, with α=5%.Results: PCTR was significantly higher with the use of primer (2.05 ± 0.08oC) than without primer (1.65 ± 0.14oC) (p=0.02), and in M1 (2.23 ± 0.22oC) compared to Mx4 (1.56 ± 0.14oC) (p<0.01). There was no difference in the PCTR in M8 (1.77 ± 0.28oC) compared to M1 or Mx4 (p>0.05), and no difference between intact (1.78 ± 0.14oC) and restored (1.92 ± 0.08oC) teeth (p=0.38). There was no influence of dentin enamel thickness in the PCTR (p=0.19). PCTR was higher in light-cure bonding of brackets with primer, especially in M1. Light-cure bonding seems less invasive without primer.