Clinical outcomes of arch expansion with Invisalign: a systematic review.

OBJECTIVE: This study aims to assess the scientific evidence regarding the clinical outcomes of Invisalign therapy in controlling orthodontic tooth movement. MATERIALS AND METHODS: An electronic search was conducted on PubMed, Cochrane Library, Web of Science, Embase, and Scopus from November 2015 to November 2022 to identify relevant articles. Methodological shortcomings were highlighted, and an evaluation of the quality of the included studies was completed using the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool. RESULTS: Fifteen non-randomized controlled trials were included in the analysis. Most non-randomized controlled trials (n=11; 73%) were rated with a moderate risk of bias according to the ROBINS-I tool. There were statistically significant differences between the pretreatment and posttreatment arches. The average expansion was significantly different from that predicted for each type of tooth in both the maxilla and mandible. Furthermore, the efficiency decreased from the anterior area to the posterior area in the upper arch. CONCLUSION: Despite the fact that arch expansion with Invisalign® is not entirely predictable, clear aligner treatment is a viable option for addressing dentition crowding. The efficacy of expansion is greatest in the premolar area. More research focusing on treatment outcomes with different materials of aligners should be conducted in the future. Overcorrection should be considered when planning arch expansion with Invisalign. In the maxilla, the expansion rate decreases from the anterior to the posterior, and presetting sufficient buccal root torque of posterior teeth may result in improved efficiency of expansion.

Psychological well-being, dental esthetics, and psychosocial impacts in adolescent orthodontic patients: A prospective longitudinal study.

INTRODUCTION: We examined the role of adolescent orthodontic patients' psychological well-being attributes (self-esteem, general body image, and positive and negative affects) and the clinical indicators of dental esthetics (orthodontists' ratings on the Index of Orthodontic Treatment Need-Aesthetic Component [IOTN-AC]), and their changes from pretreatment to posttreatment as predictors of the psychosocial impact of dental esthetics. METHODS: In this prospective longitudinal study, 1090 adolescent orthodontic patients seeking treatment at the Stomatological Hospital of Chongqing Medical University in China (mean age, 14.25 years; SD, 2.03 years) were assessed before treatment, and 68.99% (n = 752) were assessed after treatment. All subjects completed a questionnaire measuring psychological well-being attributes and 3 components of the Psychosocial Impact of Dental Aesthetics (perceptive, cognitive-affective, and social-functional). Clinical indicators of dental esthetics were measured by 3 orthodontists using the IOTN-AC. RESULTS: Substantial enhancement from pretreatment to posttreatment was found in all 3 Psychosocial Impacts of Dental Aesthetics components, confirming the positive effects of orthodontic treatment on oral health-related quality of life. Psychosocial impact of dental esthetics at baseline and improvement from pretreatment to posttreatment were found to be predicted by the patients' psychological well-being attributes (self-esteem, general body image, and negative affect) and the clinical indicators (orthodontists' rating on the IOTN-AC) at baseline, as well as their pretreatment to posttreatment change. Psychological well-being attributes had comparable or greater contribution to the Psychosocial Impact of Dental Aesthetics at baseline as well as greater improvement after treatment than the clinical indicators. These biopsychological models explained 29% to 43% of the variances in psychosocial impacts of dental esthetics outcome at baseline and about 33% of the variance in pretreatment to posttreatment improvement. CONCLUSIONS: This study establishes a biopsychological model for understanding the psychosocial impact of dental esthetics and its improvement after orthodontic treatment among adolescent orthodontic patients. The findings highlight the importance of psychological parameters in orthodontic research and clinical practice.

[The relationship between centric relation-maximum intercuspation disharmony and temporomandibular dysfunction in class II patients].

OBJECTIVE: To investigate the relationship between the degree of displacement of centric relation-maximum intercuspation (CR-MI) and temporomandibular dysfunction (TMD) in Class II patients. METHODS: The questionnaire and clinical examination were administered in 107 Class II patients and students, using the Helkimo index (Di and Ai). The differences in condylar position between CR and MI in all three spatial planes were measured using the Condyle Position Indication (CPI). RESULTS: Di positively correlated with degree of CR-MI displacement in all five displacement (P < 0.05), while Ai positively correlated with degree of CR-MI displacement except horizontal displacement. Di and Ai significantly correlated with degree of CR-MI discrepancy in all five displacement (P < 0.05); With the increasing of Di and Ai rank, the degree of CR-MI displacement and CR-MI discrepancy increased. Also, symptoms of TMD were significantly correlated with the degree of CR-MI displacement and CR-MI discrepancy except horizontal displacement (P < 0.05). Severer CR-MI displacement and CR-MI discrepancy were observed in patients who had TMD symptoms. CONCLUSION: In Class II patients, degree of CR-MI displacement is an important factor of TMD, and correlated with the severity of TMD.

Low-intensity pulsed ultrasound enhances bone marrow-derived stem cells-based periodontal regenerative therapies.

BACKGROUND: Alveolar bone loss is one of the most common consequence for periodontitis, which is a major obstacle in periodontal regeneration. Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of various disease, which also contribute to the natural bone repair process. Low-intensity pulsed ultrasound (LIPUS) is a therapeutic ultrasound used in our previous studies to promotes alveolar bone regeneration. In addition, LIPUS was found to be a promising method to enhance mesenchymal stromal cell-based therapies. In the current study, we have investigated the effects of LIPUS combined with BMSCs therapies on BMSCs homing and its potential to promote alveolar bone regeneration. METHODS: BMSCs were isolated from rat and characterized by multilineages differentiation assay. Then these cells were labeled with luciferase and green fluorescent protein (GFP) by lentivirus in vitro. Periodontal bone defect was made on the mesial area of the maxillary first molar in rats. A total of 1 × 106 Luc-GFP labeled BMSCs were injected into rat tail vein. Bioluminescence imaging was utilized to track BMSCs in vivo. The rats were sacrificed eight weeks after surgery and the samples were harvested. Micro-computed tomography (Micro-CT) was performed to evaluate alveolar bone regeneration. Paraffin sections were made and subject to hematoxylin-eosin staining, masson staining and immunohistochemistry staining. RESULTS: BMSCs display a fibroblast-like morphology and can differentiate into adipocytes or osteoblasts under appropriate condition. The transfected BMSCs are strongly positive for GFP express. Bioluminescence imaging showed that most of BMSCs were trapped in the lung. A small portion BMSCs were homed to the alveolar bone defect area in BMSCs group, while more cells were observed in BMSCs/LIPUS group compare to other groups on day 3 and 7. Micro-CT results showed that BMSCs/LIPUS group resulted in more new bone formation than other groups. Immunohistochemical results showed higher expression of COL-I and osteopontin in BMSCs/LIPUS group compared with the other groups. CONCLUSIONS: These results suggested that LIPUS can enhance BMSCs-based periodontal alveolar bone regeneration. This study provides new insights into how LIPUS might provide therapeutic benefits by promoting BMSCs homing.

Angular photogrammetric comparison of the soft-tissue facial profile of Kenyans and Chinese.

The purpose of this study was to determine the average angular dimensions that define the normal soft-tissue facial profiles of black Kenyans and Chinese and compare them with each other and with values proposed for whites. Standardized facial profile photographs, taken in natural head position, of 177 black Kenyans and 156 Chinese with normal occlusion and well-balanced faces were analyzed for 12 angular parameters. Two-sample t-tests were used to determine sex and racial differences. Kenyan and Chinese averages were compared with proposed white values using 1-sample t-tests. Eight parameters in Kenyans and 7 in Chinese showed sex differences. All angles, except for facial convexity, nasal dorsum, and inferior facial height, were different between Kenyans and Chinese. Kenyan and Chinese averages for all parameters were different from proposed white average, except for facial convexity. Nasolabial and mentolabial angles showed large individual variability and racial differences. The study demonstrated many differences in average angular measurements of the facial profiles of black Kenyans, Chinese, and white standards. Orthodontists, maxillofacial and plastic surgeons, and other clinicians working in the craniofacial region should bear these in mind when setting aesthetic treatment goals for patients of different races. Mean values from this study can be used for comparison with similar records of subjects with same ethnicity.

Efficacy of glycine powder air-polishing in supportive periodontal therapy: a systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis was conducted to assess the effects of glycine powder air-polishing (GPAP) in patients during supportive periodontal therapy (SPT) compared to hand instrumentation and ultrasonic scaling. METHODS: The authors searched for randomized clinical trials in 8 electronic databases for relevant studies through November 15, 2019. The eligibility criteria were as follows: population, patients with chronic periodontitis undergoing SPT; intervention and comparison, patients treated by GPAP with a standard/nozzle type jet or mechanical instrumentation; and outcomes, bleeding on probing (BOP), patient discomfort/pain (assessed by a visual analogue scale [VAS]), probing depth (PD), gingival recession (Rec), plaque index (PI), clinical attachment level (CAL), gingival epithelium score, and subgingival bacteria count. After extracting the data and assessing the risk of bias, the authors performed the meta-analysis. RESULTS: In total, 17 studies were included in this study. The difference of means for BOP in patients who received GPAP was lower (difference of means: -8.02%; 95% confidence interval [CI], -12.10% to -3.95%; P<0.00001; I²=10%) than that in patients treated with hand instrumentation. The results of patient discomfort/pain measured by a VAS (difference of means: -1.48, 95% CI, -1.90 to -1.06; P<0.001; I²=83%) indicated that treatment with GPAP might be less painful than ultrasonic scaling. The results of PD, Rec, PI, and CAL showed that GPAP had no advantage over hand instrumentation or ultrasonic scaling. CONCLUSIONS: The findings of this study suggest that GPAP may alleviate gingival inflammation more effectively and be less painful than traditional methods, which makes it a promising alternative for dental clinical use. With regards to PD, Rec, PI, and CAL, there was insufficient evidence to support a difference among GPAP, hand instrumentation, and ultrasonic scaling. Higher-quality studies are still needed to assess the effects of GPAP.

Low-intensity pulsed ultrasound promotes alveolar bone regeneration in a periodontal injury model.

Periodontitis is a common oral disease characterized by progressive destruction of periodontal tissue and loss of teeth. However, regeneration of periodontal tissue is a time-consuming process. Low-intensity pulsed ultrasound (LIPUS) is a widely used non-invasive intervention for enhancing bone healing in fractures and non-unions. With the hypothesis that LIPUS may accelerate periodontal regeneration, the effects of LIPUS on periodontal tissue regeneration were investigated both in vitro and in vivo. LIPUS (90 mw/cm2, 20 min/d, 1.5 MHz) was applied to stimulate dog periodontal ligament cells (dPDLCS). The mRNA expression of BSP (P < 0.05), OPN (P < 0.05) and COL3 (P < 0.05) was increased significantly in the LIPUS group. The positive stained mineralized nodules by alizarin red in the LIPUS group were greater than in the control group (P < 0.05). Eight male beagle dogs were divided into 4 groups: guided tissue regeneration (GTR) group (G1), LIPUS + GTR group (G2), LIPUS group (G3), and control group (G4, no treatment). A 4 × 5 mm2 defect was created in the buccal alveolar bone. The modeling areas in the G2 and G3 groups were then exposed to LIPUS. Eight weeks after surgery, histological assessment indicated increased periodontal tissue in the LIPUS + GTR group. Micro computed tomography (micro-CT) showed that the regenerated bone volume (BV) in the G2 was significantly higher than that in the G1, G3 and G4 groups (P < 0.05). The bone surface (BS) trabecular number (Tb.N) and trabecular thickness (Tb.Th) in G2 were markedly higher than in G4 (P < 0.05). It is concluded that LIPUS + GTR can accelerate new alveolar bone formation, with a prospective for promoting periodontal tissue repair.

[Safe zones of the maxillary posterior area for mini-implant insertion in adolescents with skeletal Class II malocclusion].

PURPOSE: The purpose of this study was to measure the interradicular spaces between the maxillary second premolar and first molar in adolescents with skeletal Class Ⅱ malocclusion, so as to obtain scientific knowledge for placing mini-implants. METHODS： Forty four cone-beam computed tomography(CBCT) images were selected, which consisted of 23 males and 21 females (average age, 14.07 years) with skeletal Class II malocclusion. CBCT was used to measure the closest interradicular distance and the shortest distance from cortical bone surface to the narrowest interradicular space apically at 1-mm intervals in 9 axial images from the cementoenamel junction(CEJ). SPSS 20.0 software package was used for statistical analysis. RESULTS: There was no significant difference in the closest interradicular distance and the shortest distance from cortical bone surface to the narrowest interradicular space between the left and right side (P>0.05), and no significant difference was found between males and females (P>0.05); The shortest distance from cortical bone surface to the narrowest interradicular space of the left apical area had positive correlation with SNA angle; The closest interradicular distance became wider toward the apical area，and the average distance of the shortest distance from cortical bone surface to the narrowest interradicular space was over 5mm in all sections. CONCLUSIONS: The distribution of interradicular spaces between the maxillary second premolar and first molar of adolescents with skeletal Class II malocclusion is learned using CBCT. These data might provide a reference for placing mini-implants.

Quantitative evaluation of palatal bone thickness for the placement of orthodontic miniscrews in adults with different facial types.

OBJECTIVES: To quantitatively evaluate palatal bone thickness in adults with different facial types using cone beam computed tomography (CBCT).  Methods: The CBCT volumetric data of 123 adults (mean age, 26.8 years) collected between August  2014 and August 2016 was retrospectively studied. The subjects were divided into a low-angle group (39 subjects), a normal-angle group (48 subjects) and a high-angle group (36 subjects) based on facial types assigned by cephalometric radiography. The thickness of the palatal bone was assessed at designated points. A repeated-measure analysis of variance (rm-ANOVA) test was used to test the relationship between facial types and palatal bone thickness. Results: Compared to the low-angle group, the high-angle group had significantly thinner palatal bones (p less than 0.05), except for the anterior-midline, anterior-medial and middle-midline areas.  Conclusion: The safest zone for the placement of microimplants is the anterior part of the paramedian palate. Clinicians should pay special attention to the probability of thinner bone plates and the risk of perforation in high-angle patients.

Impact on the upper airway space of different types of orthognathic surgery for the correction of skeletal class III malocclusion: A systematic review and meta-analysis.

OBJECTIVE: This study is aimed at assembling, through a systematic review and meta-analysis, scientific evidence related to the effects of mandibular setback (MdS) surgery and bimaxillary surgery for the correction of Class III malocclusion on the cross-sectional area (CSA) and volume of the upper airway as assessed using CT. METHODS: An electronic search was conducted on Cochrane Library, EMBASE, PubMed, Scopus and Web of Science up to June 20, 2016. The inclusion criteria were prospective or retrospective studies, with the aim of comparing the impact on the upper airway space of orthognathic surgery for the treatment of the skeletal class III malocclusion. The methodological index for non-randomized studies (MINORS) was chosen as the evaluation instrument and Revman5.3 was used for the meta-analysis. RESULTS: A total of 1213 studies were retrieved, of which only 18 met the eligibility criteria. The results of meta-analysis showed that the mean decrease in the upper airway volume after MdS surgery was 3.24 cm3 [95%CI (-5.25,-1.23), p = 0.85]; the mean decrease in minimum CSA after a combined surgery of maxillary advancement with mandibular setback (MdS + MxA) was 27.66 mm2 [95%CI (-52.81,-2.51), p = 0.51], but there was no significant decrease in upper airway volume (mean 0.86 cm3); comparison between MdS + MxA and isolated MdS showed significant differences in the CSA of the posterior nasal spine plane (PNS) and epiglottis plane (EP); statistically significant differences in nasopharynx volume (P < 0.0001) and upper airway total volume (P = 0.002) were observed, but no statistically meaningful variations existed in oropharynx volume (P = 0.08) and hypopharynx volume (P = 0.64). CONCLUSION: The results of this study suggest that bimaxillary surgery promotes less decrease on the upper airway than mandibular setback surgery alone for the correction of the skeletal class III malocclusion.

Influence of low-intensity pulsed ultrasound on osteogenic tissue regeneration in a periodontal injury model: X-ray image alterations assessed by micro-computed tomography.

OBJECTIVE: This study was conducted to evaluate, with micro-computed tomography, the influence of low-intensity pulsed ultrasound on wound-healing in periodontal tissues. METHODS: Periodontal disease with Class II furcation involvement was surgically produced at the bilateral mandibular premolars in 8 adult male beagle dogs. Twenty-four teeth were randomly assigned among 4 groups (G): G1, periodontal flap surgery; G2, periodontal flap surgery+low-intensity pulsed ultrasound (LIPUS); G3, guided tissue regeneration (GTR) surgery; G4, GTR surgery plus LIPUS. The affected area in the experimental group was exposed to LIPUS. At 6 and 8weeks, the X-ray images of regenerated teeth were referred to micro-CT scanning for 3-D measurement. RESULTS: Bone volume (BV), bone surface (BS), and number of trabeculae (Tb) in G2 and G4 were higher than in G1 and G3 (p<0.05). BV, BS, and Tb.N of the GTR+LIPUS group were higher than in the GTR group. BV, BS, and Tb.N of the LIPUS group were higher than in the periodontal flap surgery group. CONCLUSION: LIPUS irradiation increased the number, volume, and area of new alveolar bone trabeculae. LIPUS has the potential to promote the repair of periodontal tissue, and may work effectively if combined with GTR.

The effectiveness of an additional lingual infiltration in the pulpal anesthesia of mandibular teeth: a systematic review.

OBJECTIVES: The aim of this systematic review is to investigate the effect of an additional lingual infiltration on the pulpal anesthesia of mandibular teeth. METHOD AND MATERIALS: Prospective clinical trials were searched from Medline, EMBASE, Cochrane Library, Pubmed, SCI, and the China National Knowledge Infrastructure. Papers that met the inclusion criteria were accepted. Data was extracted by two investigators using a designed extraction form. The anesthetic efficacy of an additional lingual infiltration on the pulpal anesthesia of mandibular teeth was analyzed. RESULTS: Seven prospective randomized controlled trials were included. All subjects of these studies were volunteers with healthy pulps, without patients with pulpitis. Compared to buccal infiltration alone, an additional lingual infiltration following buccal infiltration is more likely to achieve a successful pulpal anesthesia in the mandibular incisor area, with a relative risk for success of 2.00 [1.08, 3.72] for 2% lidocaine and 1.32 [1.15, 1.51] for 4% articaine. For mandibular canines and premolars, the additional lingual infiltration following inferior alveolar nerve block did not enhance the anesthetic efficacy. In the mandibular molar area, no significant difference was found after an additional lingual infiltration with either 2% lidocaine or 4% articaine. CONCLUSION: An additional lingual infiltration following buccal infiltration can enhance the anesthetic efficacy compared with buccal infiltration alone in the mandibular incisor area. For mandibular canines, premolars, and molars, an additional lingual infiltration is not recommended, since no data exist to support such usage. Lingual infiltration of articaine in the mandibular teeth with pulpitis should be studied further.

Camouflage treatment of skeletal Class III malocclusion with multiloop edgewise arch wire and modified Class III elastics by maxillary mini-implant anchorage.

OBJECTIVE: To evaluate the effect of the multiloop edgewise arch wire (MEAW) technique with maxillary mini-implants in the camouflage treatment of skeletal Class III malocclusion. MATERIALS AND METHODS: Twenty patients were treated with the MEAW technique and modified Class III elastics from the maxillary mini-implants. Twenty-four patients were treated with MEAW and long Class III elastics from the upper second molars as control. Lateral cephalometric radiographs were obtained and analyzed before and after treatment, and 1 year after retention. RESULTS: Satisfactory occlusion was established in both groups. Through principal component analysis, it could be concluded the anterior-posterior dental position, skeletal sagittal and vertical position, and upper molar vertical position changed within groups and between groups; vertical lower teeth position and Wits distance changed in the experimental group and between groups. In the experimental group, the lower incisors tipped lingually 2.7 mm and extruded 2.4 mm. The lingual inclination of the lower incisors increased 3.5°. The mandibular first molars tipped distally 9.1° and intruded 0.4 mm. Their cusps moved 3.4 mm distally. In the control group, the upper incisors proclined 3°, and the upper first molar extruded 2 mm. SN-MP increased 1.6° and S-Go/N-ME decreased 1. CONCLUSIONS: The MEAW technique combined with modified Class III elastics by maxillary mini-implants can effectively tip the mandibular molars distally without any extrusion and tip the lower incisors lingually with extrusion to camouflage skeletal Class III malocclusions. Clockwise rotation of the mandible and further proclination of upper incisors can be avoided. The MEAW technique and modified Class III elastics provided an appropriate treatment strategy especially for patients with high angle and open bite tendency.