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American Journal of Orthodontics and... Jul 2022The objective of this study was to analyze the effects of aligner overtreatment on torque control and intrusion of incisors for anterior retraction with clear aligners.
INTRODUCTION
The objective of this study was to analyze the effects of aligner overtreatment on torque control and intrusion of incisors for anterior retraction with clear aligners.
METHODS
Models including a maxillary dentition without first premolars, maxilla, periodontal ligaments, attachments, and aligners were constructed and imported to finite-element software. Two groups of models were created: (1) without canine attachment and (2) with canine attachment. Overtreatment degrees (0°, 1°, 2°, 3°, 4°, and 5°) were applied for both groups.
RESULTS
Clear aligner therapy caused lingual tipping and extrusion of incisors, distal tipping and extrusion of canines, and mesial tipping and intrusion of posterior teeth, which was more significant with canine attachments except for second premolars. Aligner overtreatment produced palatal root torquing and intrusion of incisors, distal tipping of canines, and mesial tipping of second premolars, with more significant in the condition with canine attachments. With canine attachments, 1.2° overtreatment could cause bodily retraction of central incisors. Without overtreatment, stress was concentrated on apical and cervical area of both labial and lingual surfaces of periodontal ligaments. The stress value was higher with canine attachments. However, when overtreatment was added, the stress was distributed more evenly.
CONCLUSIONS
Clear aligner therapy produced lingual tipping and extrusion of incisors during anterior retraction. Overtreatment can achieve incisor intrusion and palatal root torquing, and the effect could be augmented by adding attachments on canines, which required more anchorage from posterior teeth. Appropriate overtreatment with placing attachments on canines should be designed to ensure bodily retraction and the least root resorption.
Topics: Finite Element Analysis; Humans; Incisor; Maxilla; Orthodontic Appliances, Removable; Overtreatment; Tooth Movement Techniques; Torque
PubMed: 35219555
DOI: 10.1016/j.ajodo.2021.02.020 -
The Angle Orthodontist Nov 2021To analyze the biomechanical system of anterior retraction with clear aligner therapy (CAT) with and without an anterior mini-screw and elastics.
OBJECTIVES
To analyze the biomechanical system of anterior retraction with clear aligner therapy (CAT) with and without an anterior mini-screw and elastics.
MATERIALS AND METHODS
Models including a maxillary dentition (without first premolars), maxilla, periodontal ligaments (PDLs), attachments, and aligners were constructed and imported to finite element software. Three model groups were created: (1) control (CAT alone), (2) labial elastics (CAT with elastics between the anterior mini-screw and buttons on central incisors), and (3) linguoincisal elastics (CAT with elastics between the anterior mini-screw and precision cuts on the lingual sides of the aligner). Elastic forces (0-300 g, in 50 g increments) were applied.
RESULTS
CAT alone caused lingual tipping and extrusion of the incisors. Labial elastics caused palatal root torquing and intrusion and mesial tipping of the central incisors, while linguoincisal elastics produced palatal root torquing and intrusion of both central and lateral incisors. Second premolars were intruded in all three groups, with less intrusion in the linguoincisal elastics group. For the control group, stress was concentrated on both labial and lingual root surfaces, alveolar ridge, and cervical and apical PDLs. Stress was more concentrated in the labial elastics group and less concentrated in the linguoincisal elastics group.
CONCLUSIONS
CAT produced lingual tipping and extrusion of incisors during anterior retraction. Anterior mini-screws and elastics can achieve incisor intrusion and palatal root torquing. Linguoincisal elastics are superior to labial elastics with a lower likelihood of buccal open bite. Root resorption and alveolar defects may occur in CAT, more likely for labial elastics and less likely for linguoincisal elastics.
Topics: Bone Screws; Incisor; Orthodontic Appliances, Removable; Tooth Movement Techniques; Torque
PubMed: 34061964
DOI: 10.2319/120420-982.1 -
The Angle Orthodontist Jan 2022To compare deep overbite treatment using 0.016 × 0.022 nickel-titanium lower reverse curve of Spee archwire (LRCA) or metal anterior bite turbos (ABTs). (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
To compare deep overbite treatment using 0.016 × 0.022 nickel-titanium lower reverse curve of Spee archwire (LRCA) or metal anterior bite turbos (ABTs).
MATERIALS AND METHODS
48 patients with deep overbite malocclusion were randomly allocated into two groups. Group I (age = 18.4 ± 2.8 years, overbite = 5.8 ± 0.6 mm) was treated with LRCA, while Group II (age = 18.2 ± 3.1 years, overbite = 5.2 ± 0.4 mm) was treated with ABTs bonded to the palatal surface of the upper central incisors. Two cephalograms were taken for each patient, at post-alignment stage (T1) and post-leveling stage (T2). The primary outcomes were the anteroposterior and vertical changes of the lower teeth. The secondary outcomes were the effect on upper incisor inclination and the vertical linear changes of upper teeth, to assess the sagittal and vertical skeletal changes, and to compare the duration of overbite correction.
RESULTS
42 of the 48 patients recruited completed the study (21 in each group). At T2, the lower incisors proclined more in Group I (P ≤ .001). Both lower second molars (P ≤ .001) and lower first molars (P = .001) tipped more distally, while the lower first premolar tipped more mesially, in Group I (P < .05). All cusps of both lower molars showed more extrusion in Group II (P < .05) except for the mesial cusp of lower second molars (P = .095). The duration of overbite correction was shorter using the ABTs by 1.7 months (4.85 ± 1.56 and 3.15 ± 0.93 months for Group I and Group II, respectively).
CONCLUSIONS
LRCA causes lower incisor proclination with distal tipping of lower molars, while ABTs result in lower posterior tooth extrusion.
Topics: Adolescent; Adult; Cephalometry; Humans; Incisor; Malocclusion, Angle Class II; Mandible; Overbite; Tooth Movement Techniques; Young Adult
PubMed: 34329389
DOI: 10.2319/020921-117.1 -
Dental Press Journal of Orthodontics 2023To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans.
OBJECTIVE
To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans.
MATERIAL AND METHODS
Forty-one single-rooted mandibular incisors were selected and analyzed according to anatomical characteristics, to form three groups: Group 1 - central incisors (n = 18); Group 2 - right lateral incisors (n = 10); and Group 3 - left lateral incisors (n = 13). First, enamel thickness at the proximal contact areas of the mandibular incisors was measured. Second, the mesial and distal surfaces of the lateral incisors were compared. Finally, the relationship between the tooth width and the mean enamel thickness was determined. Each tooth was scanned with a micro-CT scanner, and the image was processed with SCANCO micro-CT onboard analysis software.
RESULTS
There were no statistically significant differences in mean enamel thickness between the mesial and distal surfaces for each lateral incisor, or between contralateral lateral incisors. In all surfaces analyzed, the upper zones had statistically significantly thinner enamel (0.52 ± 0.10 mm) when compared to the middle and lower zones (0.60 ± 0.08 mm and 0.59 ± 0.08 mm, respectively). There was no correlation (r =0.07) between enamel thickness of the mandibular incisor and the tooth width.
CONCLUSIONS
The enamel thickness of the mandibular incisors is similar on the mesial and distal surfaces, with the thinnest layer located at the upper zone.
Topics: Incisor; X-Ray Microtomography; Dental Enamel; Tomography Scanners, X-Ray Computed; Mandible
PubMed: 37255131
DOI: 10.1590/2177-6709.28.2.e2321149.oar -
Acta Neurochirurgica Aug 2017Lesions of the superior cerebellar surface, pineal region, lateral and dorsal midbrain and mesial temporal lobe are challenging to treat and often require neurosurgical...
BACKGROUND
Lesions of the superior cerebellar surface, pineal region, lateral and dorsal midbrain and mesial temporal lobe are challenging to treat and often require neurosurgical intervention.
METHODS
The paramedian variation of the supracerebellar infratentorial approach utilizes the downward slope of the cerebellum to facilitate exposure and the lower density of cerebellar bridging veins away from the midline decreases the need to sacrifice larger venous channels. We also discuss our experiences with the approach, and some of the drawbacks and nuances that we have encountered as it has evolved over the years.
CONCLUSIONS
This approach is versatile and effective and the authors' surgical approach of choice for resecting these challenging lesions.
Topics: Cerebellum; Craniotomy; Humans; Mesencephalon; Pineal Gland; Postoperative Complications; Temporal Lobe
PubMed: 28493023
DOI: 10.1007/s00701-017-3196-y -
Epilepsy & Behavior : E&B Nov 2020The objective of the study was to examine the frequency and characteristics of ictal central apnea (ICA) in a selective cohort of patients with mesial or neocortical...
OBJECTIVE
The objective of the study was to examine the frequency and characteristics of ictal central apnea (ICA) in a selective cohort of patients with mesial or neocortical temporal lobe epilepsy (TLE) undergoing surface video-electroencephalography (EEG) and multimodal recording of cardiorespiratory parameters.
METHODS
We retrospectively screened 453 patients who underwent EEG in a single center including nasal airflow measurements, respiratory inductance plethysmography of thoracoabdominal excursions, peripheral capillary oxygen saturation, and electrocardiography. Patients with confirmed TLE subtype, either by magnetic resonance imaging (MRI) lesions limited to the temporal neocortex or mesial structures and concordant neurophysiologic data, or patients who underwent invasive explorations were included.
RESULTS
Ictal central apnea frequency and characteristics were analyzed in 41 patients with 164 seizures that had multimodal respiratory monitoring. The total occurrence of ICA in all seizures in this cohort was 79.9%. No significant difference was seen between mesial and neocortical temporal lobe seizures (79.8% and 80.0%, respectively). Ictal central apnea preceded EEG onset by 13 ± 11 s in 33.3% of seizures and was the first clinical sign by 18 ± 14 s in 48.7%. Longer ICA duration trended towards a more severe degree of hypoxemia.
CONCLUSIONS
In a selective cohort of TLE defined by MRI lesion and/or intracranial recordings, the frequency of ICA was higher than previously reported in the literature. Multimodal respiratory monitoring has localizing value and is generally well tolerated. Ictal central apnea preceded both EEG on scalp recordings as well as clinical seizure onset in a substantial number of patients. Respiratory monitoring and ICA detection is even more paramount during invasive monitoring to confirm that the recorded seizure onset is seen before the first clinical sign.
Topics: Electroencephalography; Epilepsy, Temporal Lobe; Humans; Magnetic Resonance Imaging; Retrospective Studies; Seizures; Sleep Apnea, Central
PubMed: 32916581
DOI: 10.1016/j.yebeh.2020.107434 -
Imaging Science in Dentistry Dec 2021This study introduces a standardized 2-plane approach using 8 landmarks to assess alveolar bone levels in mice using micro-computed tomography.
PURPOSE
This study introduces a standardized 2-plane approach using 8 landmarks to assess alveolar bone levels in mice using micro-computed tomography.
MATERIALS AND METHODS
Bone level differences were described as distance from the cemento-enamel junction (CEJ) to alveolar bone crest (ABC) and as percentages of vertical bone height and vertical bone loss, comparing mice infected with (Pg) to controls. Eight measurements were obtained per tooth: 2 in the sagittal plane (mesial and distal) and 6 in the coronal plane (mesiobuccal, middle-buccal, distobuccal, mesiolingual, middle-lingual, and distolingual).
RESULTS
Significant differences in the CEJ-to-ABC distance between Pg-infected mice and controls were found in the coronal plane (middle-lingual, mesiobuccal, and distolingual for the first molar; and mesiobuccal, middle-buccal, and distolingual for the second molar). In the sagittal plane, the distal measurement of the second molar was different. The middle-buccal, mesiobuccal, and distolingual sites of the first and second molars showed vertical bone loss relative to controls; the second molar middle-lingual site was also different. In the sagittal plane, the mesial sites of the first and second molars and the distal site of the second molar showed loss. Significantly different vertical bone height percentages were found for the mesial and distal sites of the second molar (sagittal plane) and the middle-lingual and distolingual sites of the first molar(coronal plane).
CONCLUSION
A reliable, standardized technique for linear periodontal assessments in mice is described. Alveolar bone loss occurred mostly on the lingual surface of the coronal plane, which is often omitted in studies.
PubMed: 34987999
DOI: 10.5624/isd.20210058 -
BMC Oral Health Jun 2023This 18-month randomized clinical trial aimed to compare the effectiveness of two topical fluoride applications versus placebo control on preventing development of... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
This 18-month randomized clinical trial aimed to compare the effectiveness of two topical fluoride applications versus placebo control on preventing development of approximal caries in primary teeth.
METHODS
Preschool children were recruited if they had at least one initial approximal carious lesion at the distal surface of the canines, both approximal surfaces of the first molars, or the mesial surface of the second molars assessed from bitewing radiographs. The participants were randomly allocated into 3 intervention groups: Group 1 (placebo control), Group 2 (5% sodium fluoride [NaF] varnish), and Group 3 (38% silver diamine fluoride [SDF]). All agents were applied semiannually. Two calibrated examiners evaluated the caries development from bitewing radiographs. Caries development was recorded when the baseline sound surface or initial approximal carious lesion surface developed dentin caries (beyond the outer one-third of dentine) at the follow-up examination. The intention-to-treat approach was adopted. The Chi-square test was used to analyze the effectiveness of topical fluoride agents in preventing approximal caries development and the effect of other variables. The multi-level logistic regression analysis was performed to assess the relative effectiveness of topical fluoride agents in preventing approximal caries development at the 18-month follow-up.
RESULTS
At baseline, 190 participants with 2,685 sound or initial carries at the approximal surfaces were recruited. No differences in participant demographic backgrounds, oral health related habits, or caries experience were observed among the 3 groups (P > 0.05). After 18 months, 155 (82%) participants remained in the study. The rates of developing approximal caries in Groups 1, 2, and 3 were 24.1%, 17.1%, and 27.2%, respectively (P < 0.001, χ test). After adjusting for confounding factors and clustering effect, the multilevel logistic regression analysis showed no differences in caries development rates between the 3 groups (P > 0.05). Tooth type and the extent of a carious lesion at baseline were the significant factors for caries development.
CONCLUSION
At 18-month follow-up, after adjusting for confounding factors and clustering effect, there were no statistically significant differences in preventing of approximal caries development between the semiannual application of 5%NaF, 38%SDF, or placebo.
TRIAL REGISTRATION
The study was registered in the Thai Clinical Trials Registry under the number TCTR20190315003 on 15/03/2019.
Topics: Humans; Fluorides; Fluorides, Topical; Cariostatic Agents; Dental Caries Susceptibility; Dental Caries; Sodium Fluoride; Tooth, Deciduous
PubMed: 37268914
DOI: 10.1186/s12903-023-03045-4 -
Romanian Journal of Morphology and... 2018The article presents aspects of crown and root morphology of the superior wisdom teeth, aiming to several parameters: size, shape crown and occlusal surface, number,...
The article presents aspects of crown and root morphology of the superior wisdom teeth, aiming to several parameters: size, shape crown and occlusal surface, number, topography and orientation of the roots in order to determine which the most common morphological types are. For this purpose, the upper wisdom teeth were collected. According to studies, the dominant form of the dental crown is parallelepipedic, the rectangular or parallelogram shape of the occlusal surface has large mesial and distal-oriented sides. The positive occlusal forms are generally poorly demarcated; cusps are less tall and rarely individualized. In half of the cases, the root is unique, voluminous, straight or with a curved distal tip.
Topics: Humans; Molar, Third
PubMed: 30534828
DOI: No ID Found -
Folia Morphologica 2022The aim of the study was to analyse the morphology of the apical foramen in permanent maxillary and mandibular human teeth.
BACKGROUND
The aim of the study was to analyse the morphology of the apical foramen in permanent maxillary and mandibular human teeth.
MATERIALS AND METHODS
The anatomic parameters include shapes (rounded, oval, uneven, flat and semilunar) and location (centre, buccal/labial, lingual/palatal, mesial, and distal) of the apical foramina was evaluated. The shapes and locations of apical foramen were analysed based on tooth type (central incisor, lateral incisor, canine, premolars, and molars) arch type (maxillary and mandibular), and position (anterior and posterior). All the teeth were investigated for the apical foramina shape and location using a stereomicroscope at a magnification of 10×. Descriptive statistics performed using SPSS (Version 21.0, IBM, NY, USA) at p value less than 0.05.
RESULTS
The common shape of apical foramina was round (65%) and location was centre (32%). The frequency of deviation of apical was 68% in overall teeth. Apical foramina in maxillary anterior teeth showed more deviation while posterior teeth in mandibular teeth. The most common shape of apical foramina was round (65.1%) followed by (31%) and flat and semilunar shapes are very rare in studied subjects.
CONCLUSIONS
The most frequent direction of deviation is the distal surface, followed by the mesial surface. The variation is more common in mandibular posterior teeth, while maxillary posteriors showed the least difference. The commonest shape of the apical foramen is of a round shape, followed by the oval. The oval shape of the apical foramen is most frequent with central incisors.
Topics: Bicuspid; Humans; Mandible; Maxilla; Molar; Tooth Apex
PubMed: 33330969
DOI: 10.5603/FM.a2020.0143