Effect of pH on in vitro biocompatibility of orthodontic miniscrew implants

BACKGROUND: Although the clinical use of miniscrews has been investigated on a large scale, little is known about their biocompatibility. Since low pH can affect corrosion resistance, the aim of this study was to evaluate the cytotoxic effect of orthodontic miniscrews in different pH conditions. METHODS: Four orthodontic miniscrews of stainless steel and grade IV and grade V titanium were immersed in a pH 7 and pH 4 saline solution for 1, 7, 14, 21, 28, and 84 days. Human osteogenic sarcoma cells (U2OS), permanent human keratinocytes (HaCat), and primary human gingival fibroblasts (HGF) were exposed to eluates, and the mitochondrial dehydrogenase activity was measured after 24 h to assess the cytoxicity. The results were analyzed using the Mann-Whitney U test (P < 0.05). RESULTS: When exposed to pH 7-conditioned eluates, the cell lines showed an even greater viability than untreated cells. On the contrary, the results revealed a statistically significant decrease in U2OS, HaCat, and HGF viability after exposure to eluates obtained at pH 4. Among the cell lines tested, HGF showed the most significant decrease of mitochondrial activity. Interestingly, grade V titanium miniscrews caused highest toxic effects when immersed at pH 4. CONCLUSIONS: The results suggested that at pH 7, all the miniscrews are biocompatible while the eluates obtained at pH 4 showed significant cytotoxicity response. Moreover, different cell lines can produce different responses to miniscrew eluates

Clear Aligners Treatment of Class III Subdivision with an Extraction of a Lower Bicuspid

The aim of this study was to show a case of a Class III subdivision adult patient treated with clear aligners (CA) and the extraction of a lower bicuspid. A 19-year-old male with a class III canine and molar relationship on the right side and a deviation of lower dental midline to the left asked for an aesthetic treatment. He refused orthognathic surgical procedures, so he was offered a camouflage orthodontic treatment with the extraction of lower right first premolar to achieve a canine Class I relationship and to center the lower midline. The treatment was performed with clear aligners and the use of Class III elastics to maintain distal anchorage on the right side during the canine distalization. At the end of the treatment, the occlusal objectives were achieved

Treatment of Palatally Displaced Canines Using Miniscrews for Direct or Indirect Anchorage: A Three-Dimensional Prospective Cohort Study on Tooth Movement Speed

Palatally impacted canines are usually challenging to treat in terms of both biomechanics and possible side effects. Different therapeutic approaches have been reported with or without the use of temporary anchorage devices, including the canine-first approach. Two groups of patients with palatally impacted canines were compared, observing their canine movement measured on consecutive CBCTs after three months of treatment. In the control group, impacted canines were treated with direct anchorage on miniscrews, and in the test group with indirect anchorage using a miniscrew-supported transpalatal arch. The primary outcome was the canine movement speed; the secondary outcome was the change in the root length of adjacent teeth. The median monthly apex speed was 1.05 mm in the control group (IR [0.74, 1.64]) and 0.72 mm in the test group (IR [0.27, 1.30]). The median monthly cusp displacement was 1.89 mm in the control group (IR [1.04, 2.84]) and 1.08 mm in the test group (IR [0.81, 1.91]). Approximately 50% of teeth adjacent to an impacted canine underwent a negative root length change of less than 1 mm in the majority of cases, but no significant differences were found in root length changes between groups. No statistically significant differences in the reported speeds were found, and no miniscrew failures were observed in either group

Accuracy of digital workflow for placing orthodontic miniscrews using generic and licensed open systems. A 3d imaging analysis of non-native .stl files for guided protocols

Abstract Background This study aimed to assess the accuracy of digital workflow for guided insertion of miniscrews in the anterior palate using restorative implant dentistry software and licensed software for orthodontic applications. Methods Twenty subjects (8 males, 12 females, mean age = 16.7 ± 2.1 years) were prospectively selected to receive guided insertion of bicortical palatal miniscrews. Virtual planning was performed using restorative implant dentistry software (Blue Sky Plan*, version 4.7) (group 1 = 10 subjects) and licensed orthodontic software (Dolphin Imaging Software, version 11.0) (group 2 = 10 subjects). A specific 3D Imaging technology was applied to permit the registration of the planned and achieved position of the miniscrews based on the superimposition of maxillary models. The angular deviation (accuracy error) between the planned and the achieved positions of the miniscrews were recorded. Independent Student’s test was used with statistical significance set at p value  0.05); instead, miniscrews placed on the right side were almost one degree higher than the left side (p < 0.05) in both groups. Conclusions The clinical accuracy error was similar when using generic and licensed orthodontic software for guided systems

Treatment of Palatally Displaced Canines Using Miniscrews for Direct or Indirect Anchorage: A Three-Dimensional Prospective Cohort Study on Tooth Movement Speed

Palatally impacted canines are usually challenging to treat in terms of both biomechanics and possible side effects. Different therapeutic approaches have been reported with or without the use of temporary anchorage devices, including the canine-first approach. Two groups of patients with palatally impacted canines were compared, observing their canine movement measured on consecutive CBCTs after three months of treatment. In the control group, impacted canines were treated with direct anchorage on miniscrews, and in the test group with indirect anchorage using a miniscrew-supported transpalatal arch. The primary outcome was the canine movement speed; the secondary outcome was the change in the root length of adjacent teeth. The median monthly apex speed was 1.05 mm in the control group (IR [0.74, 1.64]) and 0.72 mm in the test group (IR [0.27, 1.30]). The median monthly cusp displacement was 1.89 mm in the control group (IR [1.04, 2.84]) and 1.08 mm in the test group (IR [0.81, 1.91]). Approximately 50% of teeth adjacent to an impacted canine underwent a negative root length change of less than 1 mm in the majority of cases, but no significant differences were found in root length changes between groups. No statistically significant differences in the reported speeds were found, and no miniscrew failures were observed in either group

Validity and Reliability of New Three-Dimensional Reference Systems for Soft Tissue Analysis Using Non-Ionizing Three-Dimensional Imaging

Background: The aim of this study was to evaluate the accuracy and the repeatability of two reference systems for three-dimensional facial scans (FSs) compared with a reference system based on cone-beam computed tomography (CBCT). Subjects and methods: A total of sixty subjects, thirty growing participants (8–17 years old) and thirty non-growing participants (older than 21 years old), with FSs and full-field-of-view CBCT were included. Two different reference systems on the same FS were constructed. To assess validity, the two reference systems based on FSs were compared with the reference systems built using the CBCT scans. After two weeks, all of the FSs were reassessed to evaluate intra-operator repeatability. Reliability and repeatability were evaluated by means of parametric and non-parametric tests, intra-class correlation, the Dahlberg formula, and Bland–Altman plots (p p = 0.232). Between them, the two reference systems showed a small difference in the position of the sagittal plane (Sagittal FS1^Sagittal FS2 = 1.39 ± 1.13°). Conclusions: Both reference systems assessed in this study showed good intra-operator repeatability and their use may be suggested as reliable reference systems for FSs

Maxillary Impacted Canine and Upper Lateral Incisor Agenesis Treatment with “Canine First Technique” and Clear Aligners: A Case Report

The aim of this study was to show a case of an impacted canine in an adult patient with agenesis of the maxillary lateral incisor treated with clear aligners (CA). A 19-year-old male with a persistence of 5.3 and absence of 1.2 came to our department of the School of Orthodontics at the University of Federico II in Naples and asked for an aesthetic treatment. The Canine First approach was used to surgically expose the canine and pull it into the dental arch. In order to ensure long-term aesthetic, periodontal, and occlusal results, a treatment with CAs to close the space through the mesial placement of the canine and the enameloplasty of the tooth crown was performed. At the end of the treatment, the occlusal objectives were achieved

Digital Planning Technique for Surgical Guides for Prosthetic Implants before Orthodontic Treatment

Background: The use of digitalization allows clinicians to plan the position of dental implants in orthodontic patients treated with aligners in the beginning of their orthodontic treatment, instead of waiting until the end of orthodontic treatment, integrating implant restorations with orthodontic biomechanics. Aim: The aim of this case report is to describe a digital workflow for aligner treatment supported by implants, in which implants are placed at the beginning of the treatment and support the orthodontic treatment. Materials and Methods: Digital planning for orthodontic treatment with clear aligners and the preparation of surgical guides for implant surgery before orthodontic treatment are used to solve two multidisciplinary cases. Cone-beam computed tomography (CBCT) and virtual dental impressions are used for the virtual planning. Successively, a surgical guide for implant placement and aligners are used in the treatment plan. Results: The digital orthodontic setup with the integration of the root position allows the clinician to plan the position of dental implants on the final occlusion. The placement of the implant before the start of the orthodontic treatment allows the implants to be used as skeletal anchorage, thereby helping the orthodontic biomechanics. Conclusions: This study describes how to perform a digital workflow with orthodontic virtual planning and the design of surgical guides for implant placement. This technique is potentially promising for complex orthodontic cases

The Effects of Mandibular Advancement Device on Pressure Pain Threshold of Masticatory Muscles: A Prospective Controlled Cohort Study

AIMS: To determine if pressure pain thresholds (PPTs) of masticatory and neck muscles change after the application of a mandibular advancement device (MAD) in patients with obstructive sleep apnea (OSA). METHODS: A prospective study was conducted in a sample of 27 OSA patients (24 males and 3 females; mean age ± standard deviation [SD]: 54.8 ± 11.8, mean apnea-hypopnea index ± SD: 23.5 ± 13.3) and 27 age- and sex-matched healthy controls. Exclusion criteria were signs and symptoms of temporomandibular disorders (TMD), metabolic diseases, and use of antidepressants, analgesics, or anti-inflammatory drugs. A calibrated examiner evaluated PPTs of seven head and neck muscles bilaterally by using a Fischer algometer. In the OSA group, PPTs were recorded immediately before the MAD application (T₀), after 15 days (T₁), and after 6 months (T₂) of therapy; in the control group, PPTs were recorded at the same time intervals. PPT differences at baseline and over time within each group and between OSA and control groups were analyzed by Friedman and Mann-Whitney tests. RESULTS: There were no PPT differences between groups at baseline. In the OSA group, PPTs of temporalis and masseter muscles decreased significantly at T₁ compared with T₀ (P < .05), but no differences were found at T₂. No significant PPT differences were found in the neck muscles or over time in the control group. CONCLUSION: MAD application induces a decrease of PPTs of masticatory muscles at the beginning of the therapy, but a physiologic adaptation occurs by 6 months