Nasolabial morphological changes in patients with unilateral cleft lip and palate using a Korat-modified nasoalveolar moulding appliance with primary correction.

OBJECTIVE: The objective of this study is to measure the morphological changes of the nose and lip in patients with unilateral cleft lip and palate before and after cheiloplasty with primary rhinoplasty (primary correction) in conjunction with Korat-NAM usage. DESIGN: Longitudinal cohort study. SETTING: Cleft Center Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand. SUBJECTS: Twenty-six patients with unilateral cleft lip and palate. INTERVENTIONS: Control group: only active obturator before primary correction. Experimental group: an active obturator and Korat-NAM I before primary correction. A customized endotracheal tube was retained in the nostril for 3 weeks before switching to Korat-NAM II for 1 year. MAIN OUTCOME MEASURES: Six measurements comprising nostril rim length, nostril height, nostril sill width, columella angle, vertical lip height, and horizontal lip length were measured from the patients' photographs. All measurements, except the columella angle, were reported as the cleft side/non-cleft side value ratio. Measurements were taken at the initial appointment, immediately before, 3 weeks after, and 1 year after primary correction. RESULTS: Nostril rim length ratio, nostril height ratio, nostril sill width ratio, columella angle on the cleft side, and vertical lip height ratio were improved using Korat-NAM before and 3 weeks after primary correction. Nostril rim length and height ratios were significantly better than the control group. CONCLUSIONS: Korat-NAM improved nose and lip morphology before primary correction. An overcorrection improved the nose and lip morphology on the cleft side. The nostril rim length and vertical lip height on the cleft side also improved with Korat-NAM II 1 year after primary correction.

Cortical bone microdamage affects primary stability of orthodontic miniscrew.

BACKGROUND: The aim of this study was to investigate the effects of orthodontic miniscrew pitch and thread shape on microdamage in cortical bone. The relationship between the microdamage and primary stability was also examined. METHODS: Ti6Al4V orthodontic miniscrews and 1.0-mm-thick cortical bone pieces from fresh porcine tibia were prepared. The orthodontic miniscrews had custom-made thread height (H) and pitch (P) size geometries, and were classified into three groups: control geometry; HCPC (HC; thread height = 0.12 mm, PC; pitch size = 0.60 mm), geometry with a narrower pitch; HCPN (HC; thread height = 0.12 mm, PN; pitch size = 0.30 mm), and geometry with a taller thread height; HTPC (HT; thread height = 0.36 mm, PC; pitch size = 0.60 mm). The orthodontic miniscrews were inserted into a pilot hole in the cortical bone, and maximum insertion torque and Periotest value were measured. After insertion, the samples were stained with basic fuchsin. Histological thin sections were obtained and the bone microdamage parameters, i.e., total crack length and total damage area, and insertion state parameters, i.e., orthodontic miniscrew surface length and bone compression area were calculated. RESULTS: The orthodontic miniscrews with the taller thread height resulted in lower primary stability with minimal bone compression and microdamage; however, the narrower thread pitch led to maximum bone compression and extensive bone microdamage. CONCLUSIONS: A wider thread pitch reduced microdamage, and decreased thread height resulted in increased bone compression, ultimately resulting in increased primary stability.

One-Step Surface-Treatment Reagent (35% 3-O-Ethyl-l-ascorbic Acid Plus 50% Citric Acid Solution) Restores the Shear Bond Strength of Metal Brackets Bonded to Bleached Human Enamel: An In Vitro Study.

This study investigates how a new substance, composed of ethyl ascorbic acid and citric acid, affects the shear bond strength (SBS) of metal brackets when bonded to bleached teeth. Forty maxillary premolar teeth were used and randomly placed into four groups (n = 10): the control group did not undergo bleaching; the remaining groups underwent bleached using 35% hydrogen peroxide. In group A, 37% phosphoric acid was applied after bleaching. In group B, 10% sodium ascorbate was used for ten minutes before 37% phosphoric acid. In group C, 35%3-O-ethyl-l-ascorbic acid plus 50% citric acid solution (35EA/50CA) was applied for 5 min. The subgroups were bonded immediately after bleaching. The SBS was determined with a universal testing machine and analyzed using one-way ANOVA and then Tukey's HSD tests. Adhesive remnant index (ARI) scores were determined with a stereomicroscope and analyzed with a chi-squared test. The significance level was 0.05. Group C demonstrated significantly higher SBS values than group A (p < 0.001), but was not significantly different than the control group or group C (p > 0.05). The ARI scores were significantly different among the groups (p < 0.001). In conclusion, enamel surface treatment using 35EA/50CA improved the reduced SBS to an acceptable clinical level and reduced the clinical chair time.

Morphometric and volumetric analysis of the proximity between the incisive canal and maxillary central incisors during anterior retraction: a retrospective cone-beam computed tomography study.

OBJECTIVES: To elucidate the relationships and factors affecting the proximity between the incisive canal (IC) and maxillary central incisors and to predict the probable outcomes after anterior tooth retraction using cone beam computed tomography (CBCT). MATERIALS AND METHODS: Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction. RESULTS: All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC. CONCLUSIONS: Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.

Evaluation of Cortical Bone Microdamage and Primary Stability of Orthodontic Miniscrew Using a Human Bone Analogue.

Orthodontic miniscrews have gained popularity; however, they have some drawbacks, including screw loosening that results from bone resorption caused by excess microdamage created during screw insertion. Pilot hole preparation through the cortical bone is considered beneficial to avoid such microdamage, while an overly large pilot hole impairs primary stability. Hence, we used a human bone analogue to evaluate the microdamage and primary stability to estimate the optimal pilot hole size that would minimize the screw loosening risk. Ti6Al4V orthodontic miniscrews and 1.0-mm-thick synthetic cortical bone pieces were prepared. Various compressive loads were applied in indentation tests to test pieces' surfaces, and the microdamaged areas were confirmed as stress-whitening zones. Screw insertion tests were performed in which a miniscrew was inserted into the test pieces' pilot hole with a diameter of 0.7-1.2 mm in 0.1-mm intervals, and the stress-whitening area was measured. The insertion and removal torque were also measured to evaluate primary stability. The stress-whitening areas of the 1.0-1.2 mm pilot hole diameter groups were significantly smaller than those of the other groups (p < 0.05), whereas the 0.9 and 1.0 mm pilot hole diameter groups showed higher primary stability than other groups. In conclusion, the bone analogue could be utilized to evaluate microdamage in cortical bones and the primary stability of miniscrews.

Adjunctive use of fluoride rinsing and brush-on gel increased incipient caries-like lesion remineralization compared with fluoride toothpaste alone in situ.

Objective: The objective of this study was to compare the remineralizing effect of sodium fluoride (NaF) mouth rinse or NaF gel as an adjunct to NaF dentifrice on incipient caries-like lesions in an in situ cross-over design study, with three sessions of 30 days each. Materials and methods: Orthodontic brackets with artificial demineralized enamel slabs were attached to the upper first molars of 12 participants. A set of 3 test specimens from the same tooth was randomly assigned to each participant and allocated into three 30-day sessions: 1) brushing with 0.22% NaF dentifrice 2 times/day (F dentifrice), 2) brushing with 0.22% NaF dentifrice 2 times/day+ rinsing with 0.05% NaF before bedtime (F mouth rinse), 3) brushing with 0.22% NaF dentifrice 2 times/day + brushing with 1.1% NaF gel before bedtime (F brush-on gel). The mineral gain and lesion depth of the specimens were evaluated by micro-computed tomography. Results: The mean mineral gain from the NaF mouth rinse and the NaF brush-on gel was similar, but greater than that from the NaF dentifrice (p < .05). The NaF brush-on gel yielded the greatest mean depth of remineralization (168 µm), followed by the NaF mouth rinse (144 µm). Both depths were significantly greater than that of the NaF dentifrice (84 µm) (p < .05). Conclusions: Both 0.05% NaF mouth rinse and 1.1% NaF brush-on gel, used at bedtime, increased incipient caries-like lesion remineralization in situ in combination with brushing with NaF dentifrice twice a day.

Analysis of reversed L-loops as closing loops with anterior intrusive force.

OBJECTIVE: Intrusive forces on anterior brackets are preferable for avoiding overbite deepening. Reversing plain L-loops may create such advantageous force system during space closure. DESIGN: Force systems of reversed L-loops were compared with T-loops at three interbracket distances (IBD). SETTING: Computational study. METHODS: Using finite element analysis, loop response during simulated loop-pulling was determined for plain reversed L- and T-loop configurations at three IBDs and two sizes. Force systems were calculated on both loop ends for two activation forces. RESULTS: The 12 mm IBD reversed L-loops had almost equal M/F ratios in opposite directions at both ends. A small intrusive force was found at the canine bracket (CB). The 6 mm IBD reversed L-loops showed larger M/F ratios and extrusive forces at the premolar bracket (PB) and smaller M/F with intrusive forces at CB. The force system of 12 mm IBD T-loops showed the similar force systems as off-centered V-bends with extrusive force at CB, whilst plain 6 mm IBD T-loops showed properties similar to centered V-bends with less extrusive force at CB. CONCLUSIONS: Reversed L closing loops placed no extrusive force on the CB end at various IBDs, indicating that reversed loops will generate an intrusive force at anterior teeth during space closure.

Effect of apical portion of T-, sloped L-, and reversed L-closing loops on their force systems.

OBJECTIVE: To investigate the effect of the position of the apical portion of closing loops on the force system at both loop ends. MATERIALS AND METHODS: T-loops were compared with backward-sloped L-loops (SL) and reversed L-loops (RL). SL-loops were directed toward the anterior side; RL-loops were directed toward the posterior side. Loop response to loop pulling was determined with finite element analysis at six positions of the apical loop portion for 12-mm interbracket distance and 8-mm loop length and height. Three-dimensional models of the closing loops were created using beam elements with the properties of stainless steel. Loop responses (horizontal load/deflection, vertical force, and moment-to-force ratio) at both loop ends were calculated as well as at 100 g and 200 g activation forces. RESULTS: T-, SL-, and RL-loops with the same position of the apical portion showed approximately the same force system at both loop ends. This behavior was found across the investigated range through which the loops were moved (interbracket center to posterior bracket). CONCLUSIONS: The center of the apical portion determined the force system of the closing loops regardless of the position of the loop legs. The centers of the apical portion of the T-, SL-, and RL-loops acted like V-bend positions.

T-loop force system with and without vertical step using finite element analysis.

OBJECTIVE: To investigate the effect of vertical steps on a T-loop force system at three interbracket distances (IBDs) and their association with V-bends. MATERIALS AND METHODS: Loop response during simulated loop pulling was determined for 18 T-loop configurations (6-, 9-, and 12-mm IBD with a 2.5-mm canine bracket (CB) end and 0- (plain), 0.5-, or 1-mm vertical step). Loop length-by-height was 8 × 8 or 10 × 10 mm. Horizontal load/deflection, vertical force (Fy), and moment-to-force (M/F) ratios at loop ends were determined for 100-g and 200-g activation by finite element analysis. RESULTS: Plain, 12-mm IBD T-loops showed similar force and moment responses as off-centered V-bends (greater moment close to V-bend) without change in moment direction at the premolar bracket (PB) end; plain, 6-mm IBD T-loop responses were similar to those of centered V-bends (equal, opposing moments at each end). Adding vertical steps to the T-loops raised the M/F ratio at the PB ends enough to produce root movement, while lowering the M/F ratios at the CB ends. Increasing the step bends for shorter IBDs increased Fys and caused rapid changes in M/F ratios. Unlike plain T-loops, increasing activation in stepped T-loops caused substantial variations in M/F ratios and in amount and direction of Fys. CONCLUSIONS: Step bends can dramatically change the force system. Stepped T-loops display combined effects of V-bends and step bends.

Mechanical properties of Opus closing loops, L-loops, and T-loops investigated with finite element analysis.

INTRODUCTION: The objective of this research was to investigate the mechanical properties at both sides of Opus closing loops by analyzing the effects of loop shape, loop position, coil position, and tipping of the vertical legs. METHODS: Opus loops were compared with L-loops (with and without a coil) and a T-loop by using finite element analysis. Both upright and tipped vertical loop legs (70°) were tested. Loop response to loop pulling was simulated at 5 loop positions for a 12-mm interbracket distance and 10-mm loop lengths and heights. Three-dimensional models of the closing loops were created by using beam elements with stainless steel properties. The L-loops and Opus loops were directed toward the anterior side. Loop properties (horizontal load/deflection, vertical force, and moment-to-force ratio) at both loop ends were recorded at activation forces of 100 and 200 g. RESULTS: Upright Opus loops and L-loops showed the highest moment-to-force ratios (8.5-9.3) on the canine bracket when the loop was centered. The Opus loops and L-loops with tipped vertical legs and the T-loop had slightly lower moment-to-force ratios (7.8-8.5), with the maximum values occurring when the loop was placed close to the canine bracket end. CONCLUSIONS: Upright L-loops showed the highest moment-to-force ratios on canine brackets, whereas backward tipping of the vertical legs shifted mechanical properties closer to those of a T-loop. Loop properties varied with loop configuration and position. Clinicians should understand the specific characteristics of each loop configuration to most effectively exploit them for the desired tooth movements.

Effect of the inclination of a maxillary central incisor on periodontal stress: finite element analysis.

OBJECTIVE: To determine the effect of labiolingual inclination of a maxillary central incisor on the magnitude and distribution of stresses within the periodontal space. MATERIALS AND METHODS: Five three-dimensional finite element models of a right maxillary central incisor were created with 0°, 10°, 20°, 30°, and 40° inclination. Each incisor model was subjected to a 1 N lingual-directed force and 6-12 N·mm countertipping moment on the labial surface. The stress level within the periodontal ligament was calculated in terms of maximum principal stresses. RESULTS: With increased inclination, compressive stresses tended to increase whereas tensile stresses tended to decrease. The location where compressive stress was prevalent changed from the midroot area to the apical area on the lingual side, while the area where tensile stresses were predominant changed from the midroot area to the cervical area on the labial side. CONCLUSION: There are more compressive stresses concentrated at the apex of incisors with a high degree of inclination than in incisors that are more upright. This may be associated with the higher clinical incidence of apical root resorption found in inclined maxillary central incisors.