Pain relief by single low-level laser irradiation in orthodontic patients undergoing fixed appliance therapy

INTRODUCTION

The objective of this study was to analyze the effect of single low-level laser therapy (LLLT) irradiation on pain perception in patients having fixed appliance treatment.

METHODS

Seventy-six patients (46 women, 30 men; mean age, 23.1 years) enrolled in this single-blind study were assigned to 2 groups. The patients in group 1 (G1; 38 patients, 13 men, 25 women; mean age, 25.1 years) received a single course of LLLT (Mini Laser 2075, Helbo Photodynamic Systems GmbH & Co KG, Linz, Austria; wavelength 670 nm, power output 75 mW) for 30 seconds per banded tooth. The patients in group 2 (G2; 38 patients, 17 men, 21 women; mean age, 21.0 years) received placebo laser therapy without active laser irradiation. Pain perception was evaluated at 6, 30, and 54 hours after LLLT by self-rating with a standardized questionnaire.

RESULTS

Major differences in pain perception were found between the 2 groups. The number of patients reporting pain at 6 hours was significantly lower in G1 (n = 14) than in G2 (n = 29) (P <.05), and the differences persisted at 30 hours (G1, n = 22; G2, n = 33) (P <.05). At 54 hours, no significant differences were seen between the number of patients reporting pain (G1, n = 20; G2, n = 25), although the women had a different prevalence between G1 (n = 11) and G2 (n = 15) (P = .079). At 6, 30, and 54 hours, more than 90% of the subjects in both groups described the pain as "tearing."

CONCLUSIONS

LLLT immediately after multibanding reduced the prevalence of pain perception at 6 and 30 hours. LLLT might have positive effects in orthodontic patients not only immediately after multibanding, but also for preventing pain during treatment.

Secular trends in malocclusion in Austrian men

A comparison between occlusal deviations in the permanent dentition in the skulls of 94 19th century and 157 present-day Austrian males was made by means of the PAR Index. It was found that the contemporary dentitions showed significantly higher malocclusion scores than the 19th century sample (weighted PAR Index 11.79 and 6.62, respectively). The results show that secular changes in malocclusion have occurred during the last 100 years.

MMPs and TIMPs Expression Levels in the Periodontal Ligament during Orthodontic Tooth Movement: A Systematic Review of In Vitro and In Vivo Studies

Background: During orthodontic tooth movement (OTM), applied orthodontic forces cause an extensive remodeling of the extracellular matrix (ECM) in the periodontal ligament (PDL). This is mainly orchestrated by different types of matrix metalloproteinases (MMPs) and their tissue inhibitors of matrix metalloproteinases (TIMPs), which are both secreted by periodontal ligament (PDL) fibroblasts. Multiple in vitro and in vivo studies already investigated the influence of applied orthodontic forces on the expression of MMPs and TIMPs. The aim of this systematic review was to explore the expression levels of MMPs and TIMPs during OTM and the influence of specific orthodontic force-related parameters. Methods: Electronic article search was performed on PubMed and Web of Science until 31 January 2021. Screenings of titles, abstracts and full texts were performed according to PRISMA, whereas eligibility criteria were defined for in vitro and in vivo studies, respectively, according to the PICO schema. Risk of bias assessment for in vitro studies was verified by specific methodological and reporting criteria. For in vivo studies, risk of bias assessment was adapted from the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross-sectional study. Results: Electronic article search identified 3266 records, from which 28 in vitro and 12 in vivo studies were included. The studies showed that orthodontic forces mainly caused increased MMPs and TIMPs expression levels, whereas the exact effect may depend on various intervention and sample parameters and subject characteristics. Conclusion: This systematic review revealed that orthodontic forces induce a significant effect on MMPs and TIMPs in the PDL. This connection may contribute to the controlled depletion and formation of the PDLs' ECM at the compression and tension site, respectively, and finally to the highly regulated OTM.

Secular trends in the facial skull from the 19th century to the present, analyzed with geometric morphometrics

INTRODUCTION

Over the last 100 years, Austrian facial form has changed for various reasons, including changes in growth pattern, changes in shape pattern, or a combination of these. In this study, we explored and contrasted these 2 explanations.

METHODS

We compared cephalograms from 54 recruits in the present-day Austrian Federal Army to those from 49 dry skulls of soldiers from the Imperial Hapsburg army. Body height was measured or acquired from military records. Forty-three landmarks were located on each lateral cephalogram. Secular change and growth allometry were analyzed with standard Procrustes methods.

RESULTS

Body height correlated only weakly with size of the facial skull in these samples, and secular change in facial size (4.5% over a century) was proportionately less than that in height. Growth allometry was nearly unchanged over the century, emphasizing the typical changes of vertical to horizontal proportions and bimaxillary prognathism. Secular changes over the century took the form of far more localized remodeling around the coronoid process and the anterior maxilla. The large-scale differences, in contrast, were opposite to those one would expect from the size change.

CONCLUSIONS

The observed trends shed considerable light on secular changes in the range of dysmorphologies for clinical orthodontic correction. At the same time, the dissociation between within-century and between-century allometry is an important possibility that was hitherto typically observed only at far greater time scales than the 150 years spanned by these data.

Shear bond strength of fluoride-releasing orthodontic bonding and composite materials

Several fluoride-releasing bonding materials are available for orthodontic bracket placement. These are supposed to prevent white spot lesions during therapy. The objectives of this in vitro study were to evaluate the shear bond strength (SBS) and failure mode of a recently introduced fluoride-releasing adhesive, as well as the comparison with established orthodontic adhesives. Sixty bovine mandibular incisors were randomly allocated to three groups (n = 20): stainless steel brackets were bonded with Transbond Plus Color Change Adhesive, Transbond XT, or Light Bond. A universal testing machine was used to determine the SBS at a crosshead speed of 1 mm/minute. After debonding, the adhesive remnant index (ARI) was used to assess the adhesive remaining on the brackets. One-way analysis of variance comparing the three experimental groups showed no differences between the bonding systems for mean SBS (P = 0.27). ARI scores showed more residual adhesive on the teeth bonded with the Transbond systems (P < 0.01). As the fluoride-releasing bonding system provided sufficient mean bond strength in vitro (19.9 MPa), it may be used as an additional prophylactic measure in orthodontic therapy. However, the clinical effectiveness of its fluoride release may be questionable, as the amount of fluoride required from a bonding material to be caries preventive is still unknown.

Rebonding performance of different ceramic brackets conditioned with a new silane coupling agent

The objective of this study was to investigate the rebonding effect of a new silane coupling agent on various ceramic brackets bonded to ceramic specimen. Different ceramic brackets (Fascination 2, Clarity SL, and In-OvationC) were assigned to three groups: rebonding with new silane coupling agent, rebonding with conventional silane coupling agent, or regular bonding as control (n = 16). Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was evaluated using the adhesive remnant index score. One-way analysis of variance was applied for inferential statistics. Rebonding with the new silane coupling agent resulted in high shear bond strengths (SBSs; mean values: 37.44-41.24 MPa) and ceramic specimen fractures. Rebonding with the conventional silane coupling agent resulted in significantly (P < 0.001) lower clinically adequate SBS (mean values: 20.20-29.92 MPa) with the least ceramic specimen fractures. Regularly bonded ceramic brackets resulted in clinically adequate to high SBS (mean values: 17.06-41.56 MPa) depending on their bracket base design. Rebonded ceramic brackets showed sufficient SBS to ceramic specimen surfaces. However, increased bracket adhesion was associated with a risk of ceramic specimen surface damage. Therefore, ceramic brackets rebonded with the new silane coupling should be debonded cautiously using alternative debonding methods.

Interleukin-1β Induced Matrix Metalloproteinase Expression in Human Periodontal Ligament-Derived Mesenchymal Stromal Cells under In Vitro Simulated Static Orthodontic Forces

The periodontal ligament (PDL) responds to applied orthodontic forces by extracellular matrix (ECM) remodeling, in which human periodontal ligament-derived mesenchymal stromal cells (hPDL-MSCs) are largely involved by producing matrix metalloproteinases (MMPs) and their local inhibitors (TIMPs). Apart from orthodontic forces, the synthesis of MMPs and TIMPs is influenced by the aseptic inflammation occurring during orthodontic treatment. Interleukin (IL)-1β is one of the most abundant inflammatory mediators in this process and crucially affects the expression of MMPs and TIMPs in the presence of cyclic low-magnitude orthodontic tensile forces. In this study we aimed to investigate, for the first time, how IL-1β induced expression of MMPs, TIMPs and how IL-1β in hPDL-MSCs was changed after applying in vitro low-magnitude orthodontic tensile strains in a static application mode. Hence, primary hPDL-MSCs were stimulated with IL-1β in combination with static tensile strains (STS) with 6% elongation. After 6- and 24 h, MMP-1, MMP-2, TIMP-1 and IL-1β expression levels were measured. STS alone had no influence on the basal expression of investigated target genes, whereas IL-1β caused increased expression of these genes. In combination, they increased the gene and protein expression of MMP-1 and the gene expression of MMP-2 after 24 h. After 6 h, STS reduced IL-1β-induced MMP-1 synthesis and MMP-2 gene expression. IL-1β-induced TIMP-1 gene expression was decreased by STS after 6- and 24-h. At both time points, the IL-1β-induced gene expression of IL-1β was increased. Additionally, this study showed that fetal bovine serum (FBS) caused an overall suppression of IL-1β-induced expression of MMP-1, MMP-2 and TIMP-1. Further, it caused lower or opposite effects of STS on IL-1β-induced expression. These observations suggest that low-magnitude orthodontic tensile strains may favor a more inflammatory and destructive response of hPDL-MSCs when using a static application form and that this response is highly influenced by the presence of FBS in vitro.

The Denture Frame Analysis: an additional diagnostic tool

The purpose of this study was to evaluate the Denture Frame Analysis. This adjunctive cephalometric analysis of the lateral headfilm was introduced in Japan, but no data exist for the Caucasian population at present. One-hundred-and-six Caucasians were randomly selected and assigned to one of four groups, according to their malocclusion: Angle Classes I, II, and III, and anterior open bite. Statistical testing showed significant differences among the four groups for most of the measurements investigated. The Denture Frame Analysis distinguished the different types of malocclusion, and evaluated skeletal and dental relationships. The occlusal plane aids in the determination of the objectives and limits of orthodontic therapy.

Effect of Titanium and Zirconia Nanoparticles on Human Gingival Mesenchymal Stromal Cells

Nano- and microparticles are currently being discussed as potential risk factors for peri-implant disease. In the present study, we compared the responses of human gingival mesenchymal stromal cells (hG-MSCs) on titanium and zirconia nanoparticles (<100 nm) in the absence and presence of Porphyromonas gingivalis lipopolysaccharide (LPS). The primary hG-MSCs were treated with titanium and zirconia nanoparticles in concentrations up to 2.000 µg/mL for 24 h, 72 h, and 168 h. Additionally, the cells were treated with different nanoparticles (25−100 µg/mL) in the presence of P. gingivalis LPS for 24 h. The cell proliferation and viability assay and live−dead and focal adhesion stainings were performed, and the expression levels of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein (MCP)-1 were measured. The cell proliferation and viability were inhibited by the titanium (>1000 µg/mL) but not the zirconia nanoparticles, which was accompanied by enhanced apoptosis. Both types of nanoparticles (>25 µg/mL) induced the significant expression of IL-8 in gingival MSCs, and a slightly higher effect was observed for titanium nanoparticles. Both nanoparticles substantially enhanced the P. gingivalis LPS-induced IL-8 production; a higher effect was observed for zirconia nanoparticles. The production of inflammatory mediators by hG-MSCs is affected by the nanoparticles. This effect depends on the nanoparticle material and the presence of inflammatory stimuli.

A novel approach for gingiva thickness measurements around lower anterior teeth by means of dental magnetic resonance imaging

OBJECTIVE

This diagnostic accuracy study aims to present the first measurements of gingiva thickness around lower anterior teeth using dental magnetic resonance imaging (MRI) and to compare these measurements with two established methods: (1) gingival phenotype assessment via periodontal probing, and (2) the superimposition of cone-beam computed tomography (CBCT) scans with intraoral scans of teeth and gums.

MATERIALS AND METHODS

Ten patients with substantial orthodontic treatment need and anterior mandibular crowding were consecutively included in this clinical case series. After periodontal probing, each patient underwent a CBCT scan, an intraoral scan of the mandible, and an MRI investigation using a novel mandibula 15-channel dental coil.

RESULTS

The mean gingiva thickness was 0.72 mm measured on MRI and 0.97 mm measured on CBCT, with a mean difference between the measurement methods of 0.17 ± 0.27 mm (p < 0.001). Measurement agreement between the index tests (MRI and CBCT) and the clinical reference standard (probing) yielded an overall percent agreement of 64.94% and 47.02% for MRI and CBCT, respectively. Teeth with thin phenotypes were associated with lower soft tissue dimensions in both free (MRI: 0.56 mm vs. CBCT: 0.79 mm) and supracrestal gingiva (MRI: 0.75 mm vs. CBCT: 1.03 mm) when compared to those with thick phenotypes. However, only the measurements obtained from MRI scans showed statistically significant differences between the two phenotypes.

CONCLUSION

Dental MRI successfully visualizes delicate structures like the gingiva in the anterior mandible and achieves a high correlation with superimposed CBCT scans, with clinically acceptable deviations.

CLINICAL RELEVANCE

The present study helps to establish dental MRI as a radiation-free alternative to conventional radiographic methods.

Difference in Buccal Gingival Thickness between the Mandible and Maxilla in the Aesthetic Zone: A Systematic Review and Meta-Analysis

Background: Fragile gingival tissue is a risk factor for the development of gingival recessions. Despite the fact that gingival recessions are more commonly seen around anterior mandibular teeth, previous research has predominantly concentrated on the gingival dimensions in the anterior maxilla. The objective was to systematically compare buccal gingival thicknesses between the upper and lower jaws in individuals with healthy gingival conditions in the aesthetic zone. Methods: A comprehensive search of three databases was carried out until October 2023. Gingival thickness differences between the maxilla and mandible were evaluated by calculating the mean differences along with the corresponding 95% confidence interval (CI). Subgroup analysis was conducted based on the measurement area, measurement method, and tooth category. Results: A total of seventeen studies were included in this systematic review. Eleven studies were included in the quantitative analysis. Quantitative analysis comparing gingival thickness around 2100 teeth in the anterior mandible to 2056 teeth in the anterior maxilla revealed a statistically significant thinner buccal gingiva in the mandible (mean difference: 0.16 mm; 95% CI [-0.24, -0.07]; p = 0.0003). Conclusions: The present systematic review revealed a more delicate buccal gingiva in the anterior mandible. However, further scientific validation is required due to the considerable heterogeneity in study design and the potential presence of confounding variables.

Comparison of Skeletal and Dental Reference Planes with the Hamulus-Incisive-Papilla Plane: A Pilot Study on 3D Reconstructed Tomographies of the Skull

PURPOSE

The aim of this study was to investigate the hamulus-incisive-papilla (HIP) plane as an alternative for transferring the three-dimensional position of a patient's maxilla to an articulator.

MATERIALS AND METHODS

Camper, Frankfurt horizontal, occlusal, and HIP planes were evaluated in 21 patients' computed tomography scans and compared to one another.

RESULTS

Analysis of variance showed significant differences between all planes, with the HIP plane being closest to the occlusal plane (HIP-OP: 0.6 ± 4.0 degrees). Frankfurt and Camper planes, being more peripheral, showed higher geometric asymmetries.

CONCLUSION

The HIP plane, when used for articulator mounting, results in a closer and more technically reliable patient relationship in a clinical and laboratory context.

Heat generated by residual adhesive removal after debonding of brackets

AIM

To measure the rise in temperature during mechanical removal of residual adhesive after debonding of brackets in vitro.

METHODS

Different carbide burs on a high-speed handpiece were tested. Acrylic on the buccal surfaces of recently extracted human maxillary incisors was removed using 3 types of carbide burs (6-, 12-, 40-fluted) with a varying number of windings relative to the long axis of the shaft. The temperature was measured using a thermocouple probe in the pulp chamber of the extracted teeth.

RESULTS

The highest mean rise in temperature was measured using a 6-fluted bur (+9.4 degrees C, P < .001), followed by the 12-fluted bur (+6.5 degrees C, P <.001). The lowest rise in temperature (+1.2 degrees C, not significant) was seen with a 40-fluted bur. After 3 to 8 seconds of continuous grinding, the rise in temperature seems to slow down.

CONCLUSION

The removal of residual adhesive after debonding is best performed with fine burs. If 6-fluted burs are used, a pause after 5 to 10 seconds of continuous grinding is recommended, especially in the mandibular anterior area.

Differential gene expression and protein-protein interaction networks of human periodontal ligament stromal cells under mechanical tension

Orthodontic treatment is based on complex strategies and takes up to years until a desired therapeutic outcome is accomplished, implying long periods of high costs and discomfort for the patient. Choosing the optimal settings for force intensities in the initial phase of orthodontic tooth movement is the key to successful orthodontic treatment. It is known that orthodontic tooth movement is mainly mediated by tensile and compressive forces that are communicated to the alveolar bone via the periodontal ligament. While the revelation of the complex molecular network was already approached by transcriptomic analysis of compressed periodontal ligament cells, the entity of molecular key players activated by tensile forces remains elusive. Therefore, the aim of this study was to assess the effect of mechanical tensile forces on the gene expression profile of human primary periodontal ligament stromal cells, mimicking the initial phase of orthodontic tooth movement. A transcriptomic analysis of tension-treated and untreated periodontal ligament stromal cells yielded 543 upregulated and 793 downregulated differentially expressed genes. Finally, six highly significant genes were found in the transcriptome that are related to biological processes with relevance to orthodontic tooth movement, including apelin, fibroblast growth factor receptor 2, noggin, sulfatase 1, secreted frizzled-related protein 4 and stanniocalcin 1. Additionally, differences of gene expression profiles between individual cell donors showed a high effect size. Closer understanding of the roles of the identified candidates in the initial phase of orthodontic tooth movement could help to clarify the underlying mechanisms, which will be essential for the development of personalized treatment strategies in orthodontics.

Behavior of Primary Human Oral Keratinocytes Grown on Invisalign® SmartTrack® Material

Orthodontic clear aligner treatment is gaining tremendous popularity. The world market leader is Align Technology® and its product Invisalign®. Although numerous patients are treated with Invisalign® aligners, only little is known about the cellular effects of aligner material on oral epithelial cells. In the present study, we aimed to investigate the effects of SmartTrack® clear aligner material on directly cultured primary human oral keratinocytes (HOKs). Cell morphology and behavior were investigated by scanning electron microscopy and bright field microscopy. Aligner effects on viability were detected by cell-counting-kit (CCK)-8 and live/dead staining. Gene expression of several inflammatory and barrier proteins was assessed by qPCR. Cells cultured on tissue culture plastic served as control. Cell proliferation/viability was significantly lower in cells cultured on aligner material (p < 0.05) in comparison to control. Live/dead staining did not reveal an increase in the number of dead cells on aligner surfaces. After two and seven days of incubation, interleukin (IL)-6 expression decreased, and IL-8 expression increased in HOKs cultured on aligner surfaces. The expression of intercellular adhesion molecule 1 (ICAM-1) significantly decreased after seven days. Gene expression of epithelial barrier markers showed that integrin (ITG)-α6 significantly decreased after two and seven days. A significant decrease in ITG-β4 and E-cadherin expression levels compared to control could only be seen after seven days. We did not find any cytotoxic effect, but alterations in the cell’s barrier functions and inflammatory reaction were obvious. Clinical studies are required to give further insights into clinical reactions on the underlying aligner material of this quickly expanding orthodontic appliance.

3D printed indirect bonding trays: Transfer accuracy of hard versus soft resin material in a prospective, randomized, single-blinded clinical study

OBJECTIVES

This prospective clinical study aimed to compare transfer accuracy and immediate loss rate of hard versus soft transfer trays utilizing a CAD/CAM workflow.

METHODS

We performed virtual bracket placement on intraoral scans of adolescent patients to create individual indirect bonding trays. Orthodontic software (Appliance Designer, 3Shape, Copenhagen, Denmark) was used to design the trays, which were then produced using 3D printing technology. Patients were randomly assigned to the hard or soft resin groups with a 1:1 allocation. Subgroups were determined based on the Little's Irregularity Index and distributed equally.

RESULTS

552 brackets were bonded onto adolescent patients using 46 CAD/CAM indirect bonding trays. The linear mean transfer errors ranged from -0.011 mm (soft) to -0.162 mm (hard) and angularly -0.255° (hard) and -0.243° (soft). No statistically significant differences were found between the subgroups or soft and hard resin groups. However, the transfer accuracy of molar brackets was significantly lower in the transversal and horizontal directions. All mean transfer errors were within the limits of clinical acceptability. The loss rate was 2.4 % in the hard resin group and 2.3 % in the soft resin group. The Intra Observer Correlation was excellent.

SIGNIFICANCE

CAD/CAM technology for indirect bracket bonding has been proven reliable in a randomized clinical trial. Both hard and soft resin showed a low rate of immediate loss compared to the current literature. Soft resin was more favorable than hard resin in terms of accuracy and usability. However, the indirect bonding of molar brackets is significantly less accurate than incisor brackets.

Prevalence and characteristics of and risk factors for impacted teeth with ankylosis and replacement resorption - a retrospective, 3D-radiographic assessment

BACKGROUND

Large variation in the prevalence of ankylosis and replacement resorption (ARR) is reported in the literature and most studies have relatively small patient numbers. The present retrospective study aimed to provide an overview on prevalence, location of, and associated risk factors with ARR based on a large sample of computed tomography (CT) / cone beam computed tomography (CBCT) scans of impacted teeth. The results should allow clinicians to better estimate the risk of ARR at impacted teeth.

METHODS

The CT/CBCT scans of 5764 patients of a single center in Central Europe were screened with predefined eligibility criteria. The following parameters were recorded for the finally included population: gender, age, tooth type/position, number of impacted teeth per patient, and presence/absence of ARR. For teeth with ARR the tooth location in reference to the dental arch, tooth angulation, and part of the tooth affected by ARR were additionally registered.

RESULTS

Altogether, 4142 patients with 7170 impacted teeth were included. ARR was diagnosed at 187 impacted teeth (2.6%) of 157 patients (3.7%); 58% of these patients were female and the number of teeth with ARR per patient ranged from 1 to 10. Depending on the tooth type the prevalence ranged from 0 (upper first premolars, lower central and lateral incisors) to 41.2% (upper first molars). ARR was detected at the crown (57.2%), root (32.1%), or at both (10.7%). After correcting for confounders, the odds for ARR significantly increased with higher age; further, incisors and first/second molars had the highest odds for ARR, while wisdom teeth had the lowest. More specifically, for 20-year-old patients the risk for ARR at impacted incisors and first/second molars ranged from 7.7 to 10.8%, but it approximately tripled to 27.3-35.5% for 40-year-old patients. In addition, female patients had significantly less often ARR at the root, while with increasing age the root was significantly more often affected by ARR than the crown.

CONCLUSION

ARR at impacted teeth is indeed a rare event, i.e., only 2.6% of 7170 impacted teeth were ankylosed with signs of replacement resorption. On the patient level, higher age significantly increased the odds for ARR and on the tooth level, incisors and first/second molars had the highest odds for ARR, while wisdom teeth had the lowest.

A cephalometric comparison of skulls from different time periods--the Bronze Age, the 19th century and the present

The aim of this study was to evaluate secular trends by means of orthodontic measurements on lateral cephalograms. We use roentgenograms from three populations: 22 Bronze Age skulls from a cemetery near Hainburg/Austria, 140 soldiers who served in the Hapsburg Imperial Army in the late 19th century, and 154 contemporary recruits of the Austrian Federal Army. Using conventional morphometric analysis, no statistically significant differences could be established. But applying geometric morphometrics to the 2D-coordinates of the pentagon composed of the landmarks Sella, Nasion, Articulare, Gonion and Menton, some biologically interpretable differences were detected, the size allometry between the 19th- and 20th-century populations being the only notable one. We conclude that landmarks should be digitized directly (and many more of them) and that conventional methods used in clinical orthodontics are inappropriate for addressing the scientific questions approached here.

CAD/CAM indirect bonding trays using hard versus soft resin material: a single-blinded in vitro study

OBJECTIVES

The present in vitro study aimed to evaluate the accuracy of three-dimensional (3D) printed indirect bonding trays consisting of hard or soft resin materials produced using computer-aided design and manufacturing (CAD/CAM).

METHODS

Forty-eight dental casts were 3D printed. Four groups based on frontal crowding were defined and divided into hard- and soft-resin groups. After virtual bracket positioning on the digital models, the transfer trays were 3D printed. To evaluate the accuracy of the procedure, measurements were performed using a digital overlay of the virtual (target) bracket position and a post-bonding scan. The horizontal, transverse, and vertical deviations and angular discrepancies were analyzed. The loss rate was evaluated descriptively as a percentage.

RESULTS

A total of 553 brackets were bonded using 24 soft and 24 resilient indirect bonding trays. The mean deviations were of 0.05 mm (transversal), 0.05 mm (horizontal), 0.09 mm (vertical), 0.13° (angulation) in the resilient resin group and of 0.01 mm (transversal), 0.08 mm (horizontal), 0.08 mm (vertical), 0.37° (angular) in the soft resin group. The loss rate was 6.9% and 0.7% in the hard and soft resin groups, respectively. Angular deviations were significantly higher in the soft resin group (P = 0.009), whereas the loss rate was considerably higher in the hard resin group (P < 0.001).

SIGNIFICANCE

The findings indicate that indirect bonding using CAD/CAM is an accurate procedure in the laboratory setting. Soft resins are considered favorable for loss rate and useability.

Influence of malocclusion on OHRQoL in adolescents in initial orthodontic treatment phase

OBJECTIVES

Besides correcting malocclusions, another main objective of orthodontic treatment is to improve patients' oral health-related quality of life (OHRQoL). This study aimed to assess changes in OHRQoL of children within the first six months of orthodontic therapy with fixed orthodontic appliances.

METHODS

85 patients aged 11 to 14 years requiring fixed orthodontic appliance therapy were included. The children completed the German version of the Child Perceptions Questionnaire (CPQ-G-11-14) before (T0), 1 month (T1) and 6 months (T2) after the start of orthodontic treatment. The type of malocclusion was categorized according to the Index of Orthodontic Treatment Need (IOTN).

RESULTS

The initial type of malocclusion affected the children's OHRQoL, whereas gender and age did not. The IOTN dental health component (DHC) had a significant impact on the CPQ score (median CPQ of 15.00 for the group DHC 4 vs. 22.50 for DHC 5, p = 0.032). The onset of orthodontic treatment initially affected the CPQ domains "Oral symptoms" and "Functional limitations, with a change versus baseline of 2.00 (p = 0.001), but improved again after 6 months. Regression analysis demonstrated that children with an IOTN DHC 5 malocclusion experienced a greater impact on their ORHQoL, as indicated by a CPQ score 7.35 points higher than that of children with an IOTN DHC 4 malocclusion (p = 0.015).

CONCLUSIONS

At the beginning of orthodontic treatment, the OHRQoL slightly worsens, probably due to the discomfort and appearance of the appliances. However, 6 months after the start of orthodontic treatment, OHRQoL improved again in patients with severe malocclusion (IOTN 4 and 5), and approached baseline values.

CLINICAL RELEVANCE

The results help the clinician to better understand specific aspects of oral health that may be affected by different malocclusions, thereby improving the child's satisfaction and overall quality of life.

Exploring the impact of orthodontic appliances on the oral microbiome and inflammatory parameters

BACKGROUND

The symbiotic relationship between the oral microbiome and the host immune system is a prerequisite of oral health. Disruptions to this system can be associated with the development of diseases like dental caries. Introducing orthodontic treatments, such as aligners and fixed appliances, might impact this microbial ecosystem. This study evaluated potential changes in salivary microbiome and the level of inflammatory marker myeloid-related protein 8/14 in patients undergoing orthodontic treatment with aligners or fixed appliances.

METHODS

Forty-eight patients were divided into two groups for treatment with fixed appliances or clear aligners. Unstimulated saliva samples were collected at baseline, three, and six months for microbiome analysis via 16 S rRNA sequencing and MRP-8/14 level measurement using ELISA.

RESULTS

Among 503 identified microbial species, no significant changes were noted in overall microbiome. A considerable increase of caries-relevant species could not be observed either. MRP-8/14 levels remained unchanged across treatments, indicating no alterations in the inflammatory level.

CONCLUSION

Orthodontic treatment with fixed or removable appliances does not significantly alter the salivary microbiome or influence inflammation, suggesting that these interventions are unlikely to affect oral health negatively.

Transfer accuracy of 3D printed versus CAD/CAM milled surgical guides for temporary orthodontic implants: A preclinical micro CT study

OBJECTIVES

Temporary anchorage devices (TADs) have become an integral part of comprehensive orthodontic treatments. This study evaluated the transfer accuracy of three-dimensional (3D) printed and computer-aided design/computer-aided manufacturing (CAD/CAM) milled surgical guides for orthodontic TADs using micro-computed tomography (CT) imaging in a preclinical trial.

METHODS

Overall, 30 surgical guides were used to place TADs into typodonts; 3D printing and CAD/CAM milling were used to produce the guides. The virtual target positions of the TADs were compared to the real positions in terms of spatial and angular deviations using digital superimposition. Micro-CT imaging was used to detect the positions. To evaluate reliability, two investigators collected the measurements twice. Intra-rater and inter-rater correlations were tested.

RESULTS

In total, 60 palatal TADs were evaluated. The mean coronal deviations in the print group ranged from 0.15 ± 0.20 mm to 0.71 ± 0.22 mm, whereas in the mill group, they ranged from 0.09 ± 0.15 mm to 0.83 ± 0.23 mm. At the apical tip, the overall deviations in the print group ranged from 0.14 ± 0.56 mm to 1.27 ± 0.66 mm, whereas in the mill group, they ranged from 0.15 ± 0.57 mm to 1.09 ± 0.44 mm. The mean intra-class and inter-class correlation coefficients ranged from 0.904 to 0.987. No statistically significant differences were found between the groups.

CONCLUSIONS

CAD/CAM milled guides yielded spatial and angular accuracies comparable to those of 3D printed guides with notable deviations in the vertical positioning of TADs.

CLINICAL SIGNIFICANCE

Digital planning of orthodontic temporary implants combines clinical predictability and the safety of surrounding tissue. Therefore, the transfer accuracy of the guides is crucial. This preclinical study was the first to evaluate CAD/CAM milling for orthodontic guides and found its accuracy comparable to that of the current "gold standard".