Short-term skeletal and dentoalveolar effects of overexpansion.

OBJECTIVES: To evaluate whether the amount of rapid maxillary expansion differentially affects the skeletal and dentoalveolar changes that occur. MATERIALS AND METHODS: This randomized controlled trial included 23 patients who had rapid maxillary expansion (RME). Subjects were randomly assigned to a conventional expansion control group (n = 12) or an overexpansion group (n = 11), who started treatment at 13.2 ± 1.5 and 13.8 ± 1 years of age, respectively. Cone beam computed tomography scans (11 cm) were obtained prior to rapid maxillary expander (RME) delivery and approximately 3.7 months later. Initial hand-wrist radiographs were used to determine the participants' skeletal maturity. RESULTS: The RME screws were activated 5.6 ± 1.2 mm and 10.1 ± 0.6 mm in the conventional and overexpansion groups, respectively. Overexpansion produced significantly greater expansion of the nasal cavity (2.1X-2.5X), maxillary base (2.3X), buccal alveolar crest (1.4X), and greater palatine foramina (1.9X). Significantly greater intermolar width increases (1.8X) and molar inclination (2.8X) changes were also produced. The nasal cavity and maxillary base expanded 23%-32% as much as the screws were activated. Skeletal expansion was positively correlated with RME screw activation (R = 0.61 to 0.70) and negatively correlated (R = -0.56 to -0.64) with the patients' skeletal maturation indicators (SMIs). Together, screw activation and the patients' SMI scores explained 48%-66% of the variation in skeletal expansion. CONCLUSIONS: This pilot study shows that overexpansion produces greater changes than conventional expansion, with greater skeletal effects among less mature patients.

How different time intervals between repeated applications of CPP-ACP fluoride varnish effect smooth surface enamel demineralization?

OBJECTIVES: To evaluate the preventive effects of different time intervals between repeated applications of the CPP-ACP fluoride varnish on enamel demineralization. METHODS: Human teeth were sectioned and randomly allocated to three groups: 4-week, 6-week, and 12-week (N = 22/group). Baseline images of the enamel surfaces were obtained using the FluoreCam recording the area, intensity, and impact of baseline enamel demineralization. All groups received fluoride varnish applications at the beginning of the experiment. The varnish was reapplied every 4 or 6 weeks in the 4-week and 6-week groups, respectively. Following each application, the groups underwent thermo-cycling, tooth brushing and pH cycling to simulate the time effect. After 12 weeks, the enamel surfaces were reimaged using the FluoreCam. Within and between-group differences in the area, intensity and impact of demineralization were evaluated. RESULTS: At baseline, there were no significant between-group differences for area, intensity, or impact. Statistically significant (p<0.001) enamel demineralization occurred over time within each group. There were significant between-group differences in the changes that occurred in area (P = 0.004), impact (P = 0.022), but not intensity. The 12-week had significantly larger areas of demineralization than the 6-week (P = 0.041) and 4-week (P = 0.001) groups. Changes in impact was significantly (P = 0.007) greater in the 12-week group than 4-week group, but not greater than the 6-week group. There were no statistically significant differences between 4- and 6-week groups in the changes of area, intensity, or impact. CONCLUSION: Reapplication of the CPP-ACP fluoride varnish every 4-6 weeks, is more effective in reducing enamel demineralization compared to every 12 weeks.

The quality of etched enamel in different regions and tooth types and its significance in bonding and the development of white spot lesions.

OBJECTIVES: To quantify differences in the etch quality of enamel within and between human teeth, which has not previously been attempted. MATERIALS AND METHODS: The buccal right and left halves of 27 extracted human teeth were randomly allocated to scanning electron microscopy (SEM) or micro-computed tomography (µCT) for evaluation. The buccal surfaces were pumiced, etched with 37% phosphoric acid gel etchant for 15 seconds, rinsed, and air dried. Each tooth was divided into three regions (incisal, middle, and cervical) and viewed after etching at 1200× magnification with SEM. The µCT scans were taken before and after etching to calculate apparent and material mineral densities. RESULTS: SEM showed greater aprismatic enamel and poorer etch quality (ie, significantly less percentage enamel) for the posterior than anterior teeth and for the cervical region than for the incisal and middle regions of all teeth. Although there were no density differences prior to etching, µCT demonstrated that etching increased material density significantly more for the anterior than posterior teeth. Prior to etching, the enamel in the cervical regions was significantly less dense than the enamel in the middle or incisal regions. Etching significantly increased the material density of all three regions, which decreased initial regional differences. After etching, the apparent density of the cervical region remained significantly lower than the densities of the other two regions. CONCLUSIONS: Based on SEM and µCT, there is greater aprismatic enamel and inferior etch quality in the cervical regions of all tooth types and is clinically significant in explaining the failure of sealant retention and the propensity for white spot lesions.

Keys to Class II correction: A comparison of 2 extraction protocols.

INTRODUCTION: The purpose of this study was to evaluate the effects of 2 extraction patterns on incisor and molar movements in patients with growing Class II Division 1. METHODS: The sample included 54 patients 10-17 years of age treated by 2 private practice orthodontists using Tweed directional force mechanics, 4 premolar extractions, J-hook headgears, and Class II elastics or Saif springs. The sample was divided on the basis of having maxillary and mandibular first premolars (4/4) or maxillary first and mandibular second premolars (4/5) extracted. Each group included 27 patients. Treatment lasted 2.8 ± 0.60 years and 2.6 ± 0.54 years for the 4/4 and 4/5 groups, respectively. Pretreatment (T1) and posttreatment lateral cephalograms and dental casts were evaluated. Cranial base, mandibular, and maxillary superimpositions were performed to quantify tooth movements and displacements. RESULTS: There were no statistically significant T1 between-group differences in crowding or in the SNA, SNB, ANB, and MPA angles. Analyses of covariance, controlling for statistically significant (P <0.05) differences in T1 mandibular incisor position, showed that mandibular first premolars extractions produced greater (1.6 mm) mandibular incisor retraction than second premolar extractions. The mandibular first molars were protracted significantly more (0.7 mm) after the second premolar than the first premolar extractions. Within-group changes of the MPA, between-group differences in the changes in MPA, and the amount of vertical eruption of the maxillary and mandibular molars were not significantly different between the 2 extraction patterns. CONCLUSIONS: Extraction of mandibular second premolars enhances Class II molar correction, with greater mesial first molar movement and less distal incisor movement. Neither extraction pattern has an effect on the MPA or the vertical dimension (ie, there was no "wedge effect").

Effects of transverse bodily movements of maxillary premolars on the surrounding hard tissue.

INTRODUCTION: This experimental study was designed to (1) produce buccal translation of maxillary premolars and (2) evaluate the effects on the buccal alveolar bone. METHODS: A randomized split-mouth study was designed based on 7 adult male beagle dogs. The experimental side received a custom cantilever appliance fabricated to produce a translatory force through the maxillary second premolar's center of resistance. The contralateral second premolar received no appliance and served as the control. The premolars underwent 6-7 weeks of buccal translation, followed by 3 weeks of fixed retention. Biweekly tooth movements were evaluated using intraoral and radiographic measurements. Pretreatment and posttreatment models were measured to assess tipping. Three-dimensional microscopic tomography was used to quantify the amount and density of buccal bone. Bone formation and turnover were assessed using fluorescent labeling, hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, and bone sialoprotein immunostaining. RESULTS: The applied force (100 g of force) translated (1.4 mm) and minimally tipped (4°) the experimental teeth. Lateral translation produced dehiscences at the mesial and distal roots, with 2.0 mm and 2.2 mm loss of vertical bone height, respectively. Bone thickness decreased significantly (P < 0.05) at the apical (∼0.4 mm), midroot (∼0.4 mm), and coronal (∼0.2 mm) levels. Fluorescent imaging, hematoxylin and eosin staining, and immunostaining for bone sialoprotein all showed new bone formation extending along the entire periosteal surface of the second premolar's buccal plate. Tartrate-resistant acid phosphatase staining demonstrated greater osteoclastic activity on the experimental than that of control sections. CONCLUSIONS: New buccal bone forms on the periosteal surface during and after tooth translation, but the amount of bone that forms is less than the amount of bone loss, resulting in a net decrease in buccal bone thickness and a loss of crestal bone.

Is there a relationship between dental crowding and the size of the maxillary or mandibular apical base?

OBJECTIVE: To determine whether apical base size is related to dental crowding. MATERIALS AND METHODS: Digital scans of dental casts were taken of 75 untreated Class I adults to measure maxillary and mandibular tooth size, dental arch perimeters, intermolar widths, and intercanine widths. Cone beam computed tomography (CBCT) images were used to measure the apical base of the maxilla and mandible, including the total cross-sectional area, five basal arch perimeters and five basal arch widths. Principal components factor analyses were performed to evaluate the relationships between the apical base size and tooth-size-arch-length discrepancies (TSALD). RESULTS: The dental arch and maxillary apical base measures were significantly larger in males than females. There were only limited sex differences in mandibular apical base size. The dental arch measurements were smaller in subjects with greater upper and lower TSALD. Maxillary and mandibular apical base dimensions were positively interrelated. Low-to-moderate correlations were found between the size of the maxillary apical base and TSALD. The size of the mandibular apical base was not related to upper or lower TSALD. Tooth size showed little to no relationship with TSALD. CONCLUSIONS: Although maxillary apical base size is related to maxillary and mandibular crowding in subjects with Class I malocclusion, mandibular apical base size is not.

Risk assessments in orthodontic patients developing white spot lesions.

AIM: To determine whether caries risk factors, including cariogenic bacterial levels and salivary function, can be used to identify orthodontic patients who develop white spot lesions (WSL). METHODS: This prospective case-control study comprised 50 patients 11-17 years of age, including 25 controls and 25 cases who developed new WSL during treatment. WSL, oral hygiene and fluorosis were evaluated from intraoral photographs. The biofilm was assessed with bacterial cultures and adenosine triphosphate (ATP) bioluminescence. Salivary analyses were performed to determine the pH of saliva and flow rates. A survey was used to assess snacking frequency, oral hygiene and fluoride utilization. RESULTS: There were no between-group pretreatment differences in WSL. Cases reported eating sugary foods significantly more often than the controls. There was a significant decline in oral hygiene during treatment, with no significant between-group difference. There also were no statistically significant between-group differences in the amount of saliva, buffer, ATP bioluminescence and bacterial levels. Both groups showed lower than normal buffer capacity and high bacterial levels. CONCLUSION: Cases had greater sugar intake between meals than controls. ATP bioluminescence, Streptococcus mutans levels with Saliva Check Mutans, and salivary factors do not identify patients who develop WSL.

Localizing the osseous boundaries of micro-osteoperforations.

INTRODUCTION: The aim of this work was to determine how far the effects of micro-osteoperforations (MOPs) extend within bone by quantifying the damage caused and the short-term bony adaptations that occur in and around the injury site. METHODS: With the use of a split-mouth design, 34 MOPs (Propel) were randomly placed in the mandibular furcal bone of 13 beagle dogs either 2 or 4 weeks before killing them. The control side received no treatment. Vickers hardness microindentation, microscopic computed tomography, and histologic analyses were performed to evaluate the bone surrounding the MOPs. RESULTS: Microfractures produced during insertion extended ∼0.6 mm from the MOP sites. Cortical and trabecular bone were significantly less dense on the experimental than on the control side up to 4.2 mm from the edge of the MOP, but side differences were small (<5%) beyond 1.5 mm from the MOP. Experimental cortical bone was significantly softer than the control bone up to 0.8 mm from the MOP after 2 weeks of healing, and up to 0.5 mm from the MOP after 4 weeks of healing. Hematoxylin and eosin stained sections of cortical and trabecular bone showed small areas of woven bone within the MOP sites after 2 weeks, and acellular areas of bone extending ∼0.5 mm from the MOP. After 4 weeks of healing, there were greater amounts of woven bone, as well as early signs of lamellar bone, in and around the MOP sites. Markedly increased TRAP activity extending up to 2.5 mm from the MOP was evident after 2 weeks, but not after 4 weeks. Vital fluorescence staining showed diffuse bone deposition on the experimental side up to 1.5 mm from the MOP margin. CONCLUSIONS: When MOPs are performed in beagle dogs, demineralization is transient and healing of the injured area, as well as remineralization of bone affected by MOP placement, begins during the first 2 weeks. Although the transient effects extend farther, the principal effects extend only ∼1.5 mm from the MOP site.

Effects of micro-osteoperforations on tooth movement and bone in the beagle maxilla.

PURPOSE: The purpose of this study was to determine how micro-osteoperforations (MOPs) affect tooth movements, bone turnover, bone density, and bone volume. METHODS: A split-mouth experimental design with 7 beagle dogs was used to evaluate bone surrounding maxillary second premolars that had been retracted for 7 weeks. One month after the maxillary third premolars were extracted, 8 MOPs (1.5 mm wide and 7 mm deep) were created without flaps with the use of the Propel device (6 were placed 3 mm distal to the second premolar and 2 were placed in the premolar furcation) on one randomly chosen side. The maxillary second premolars were retracted bilaterally with the use of 200 g nickel-titanium closed coil springs. Tooth movements were measured intraorally and radiographically. Microscopic computed tomography was used to evaluate the material density and volume fraction of bone distal to the premolars. Hematoxylin and eosin-stained and fluorescent sections were used to examine the bone remodeling. RESULTS: Neither the intraoral (P = 0.866) nor radiographic (P = 0.528) measures showed statistically significant side differences in tooth movements. There also were no statistically significant differences in the density (P = 0.237) or volume fraction (P = 0.398) of bone through which the premolars were being moved. Fluorescent and histologic evaluations showed no apparent differences in osteoblasts, osteoclasts, or mineralization of bone near the teeth being moved. Bone healing was evident in and near the MOP sites, which had nearly but not completely healed after 7 weeks. Regions of acellular bone were evident extending ∼0.8 mm from the MOP sites. CONCLUSIONS: MOPs placed 3 mm away from teeth do not increase tooth movements and have limited and transitory effect on bone.

Do orthopedic corrections of growing retrognathic hyperdivergent patients produce stable results?

OBJECTIVES: To determine if posterior dental intrusion produces stable orthodontic and orthopedic corrections in growing retrognathic hyperdivergent patients. MATERIALS AND METHODS: The sample included 14 subjects (five males and nine females), who were 13.4 ± 0.7 years pretreatment, treated for 3.5 years, and followed for 3.6 years posttreatment. During the initial orthopedic phase, 150 g NiTi coil springs were attached to two palatal miniscrew implants (MSIs) for maxillary intrusion; two buccal mandibular MSIs were used for posterior vertical control. Full orthodontic therapy was initiated to correct the malocclusions during the orthodontic phase. Patients were recalled a minimum of 1 year posttreatment (mean 3.6 ±1.6 years). Patients were compared to matched untreated controls. RESULTS: Relative to the untreated controls, during treatment and retention, maxillary and mandibular molars underwent 2.8 mm and 3.7 mm of relative posterior intrusion, respectively. Maxillary incisors were extruded 1.3 mm and the mandibular incisors underwent 2.9 mm of relative intrusion. Overall orthopedic changes included a reduction in the mandibular plane angle (MPA; 3.3°), an increase in SN-Pg (2.4°), an increase in S-N-B (2.1°), and a 4.3 mm relative reduction in anterior facial height. The maxillary incisors, which showed 0.6 mm of intrusion (relative to controls), was the only dental or skeletal measure to show a statistically significant between-group posttreatment difference. CONCLUSIONS: Except for maxillary incisor position, the substantial dental intrusion and associated orthopedic corrections that were produced during treatment remained stable post-treatment.

Preventive effects of carbon dioxide laser and casein phosphopeptide amorphous calcium phosphate fluoride varnish on enamel demineralization: A comparative, in vitro study.

AIM: The aim of the present study was to compare the effects of carbon dioxide (CO2 ) laser and casein phosphopeptide amorphous calcium phosphate (CPP-ACP)fluoride varnish on enamel demineralization. METHODS: Human teeth were randomly assigned to three groups. The enamel was treated with fluoride varnish, 10.6 µm CO2 laser, or no treatment (control), followed by 9 days of pH cycling. Baseline and final FluoreCam images were used to quantify the area, intensity, and impact of demineralization; cross-sectional microhardness was used to measure the mechanical properties of the enamel. RESULTS: There were statistically-significant changes in the area, intensity and impact of demineralization in the control and laser groups (P < 0.05), but not in the fluoride group. The control group showed a significantly greater area and impact of enamel demineralization compared to the fluoride group. The area of demineralization in the laser group was significantly greater than that of the fluoride group. Enamel demineralization of the laser and control groups was comparable. The fluoride group showed statistically-significant harder enamel than the control at 20, 40, and 60 µm depths; the laser group enamel was significantly harder than the control at 20 and 40 µm depths. The fluoride group showed statistically-significant harder enamel than the laser group at 20 µm depth. CONCLUSIONS: CPP-ACP fluoride varnish is more effective than CO2 in preventing enamel demineralization.

The longevity of casein phosphopeptide-amorphous calcium phosphate fluoride varnish's preventative effects: Assessment of white spot lesion formation.

OBJECTIVES: To test how long casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) fluoride varnish prevents enamel demineralization in vitro. MATERIALS AND METHODS: Human molars and premolars were sectioned buccolingually and randomly assigned to two groups. Standardized pretreatment images of enamel surfaces were obtained using FluoreCam. The control group received no treatment, and the experimental group received an application of CPP-ACP fluoride varnish. Over simulated periods of 2, 4, 8, and 12 weeks, specimens were placed in a toothbrushing simulator, thermocycled, subjected to 9 days of pH cycling, and imaged with FluoreCam. Samples were sectioned and polished for polarized light microscope (PLM) evaluation. RESULTS: There were statistically significant time ( P < .001) and varnish ( P < .001) effects on area, intensity, and impact of enamel demineralization. The control group showed significant and progressive demineralization over the 12 weeks ( P < .001). The experimental group revealed no significant demineralization during the first 4 weeks ( P > .05) and significant ( P < .001) increases thereafter. Experimental demineralization after 12 weeks was comparable to 2-week demineralization in the controls, with significant between-group differences ( P < .001) in enamel demineralization at all time points. PLM of the control and experimental groups revealed lesion depths of 90 ± 34 µm and 37 ± 9 µm, respectively. CONCLUSIONS: Within the limitations of this in vitro study, CPP-ACP fluoride varnish prevents enamel demineralization for at least 4 weeks and limits demineralization up to 12 weeks.

Effect of automated messaging on oral hygiene in adolescent orthodontic patients: A randomized controlled trial.

OBJECTIVE: To determine whether automated text messages sent daily to adolescent orthodontic patients improves oral hygiene more than weekly reminders. MATERIALS AND METHODS: A blinded, prospective, randomized controlled trial was designed to evaluate the effects of automated messages on oral hygiene. Subjects were recruited from patients undergoing orthodontic treatment at the Texas A&M University College of Dentistry, Department of Orthodontics. They were being treated with a variety of fixed full appliances in both arches. Subjects were randomly assigned to either a once-a-week text message group or a daily text message group. There were 52 females and 27 males who were 12 to 17 years of age. Oral hygiene was measured at the beginning of the study and again 8.6 ± 0.9 weeks later. RESULTS: The daily reminder group (N = 42) had significantly greater improvements in oral hygiene compliance than the weekly reminder group (N = 37). The daily score decreases were 48%, 21% and 19% for the bleeding index (BI), plaque index (PI), and gingival index (GI), respectively. The weekly score decreases were 27%, 14% and 13% for the BI, PI, and GI. There were no sex differences in hygiene changes during the study. The 42% of patients who completed the survey at the end of the study wanted more frequent messages and reported that messages related to decreasing treatment time were the most effective, while those related to oral hygiene were the least effective. CONCLUSIONS: Daily text messages are more effective at improving oral hygiene than weekly text messages.

White spot lesions: Does etching really matter?

AIM: The clinical significance of acid etching prior to orthodontic bonding is controversial. In the present study, we evaluated the effect of 15 seconds of acid etching on enamel demineralization. METHODS: Twenty-seven human molars were sectioned and assigned to two groups. Under standardized conditions, the enamel surfaces were imaged using FluoreCam to obtain baseline data. Group 1 was etched using 37% phosphoric acid for 15 seconds, rinsed with water, and then imaged again; group 2 was only rinsed with water. Water rinse was collected for calcium chemical analysis using inductively-coupled plasma auger electron spectrometry. Both groups were subjected to 9 days of pH cycling, after which final FluoreCam images were obtained. RESULTS: Group 1 showed a significant increase in lesion area (P=.012), decrease in light intensity (P=.009), and decrease in impact (P=.007) after acid etching. The amount of calcium that leached out over the 15 seconds was 14 ppm ±2.4 (0.35 mmol/L±0.06). Following pH cycling, there was no statistically-significant between-group difference in overall enamel demineralization. CONCLUSION: Initial demineralization caused by 15 seconds of acid etching does not increase enamel susceptibility to further demineralization. This suggests that acid etching does not increase the risk of developing white spot lesions during orthodontics.

Treatment changes of hypo- and hyperdivergent Class II Herbst patients.

OBJECTIVES: To determine the relative effects of Herbst appliance therapy in hypo- and hyperdivergent patients. MATERIALS AND METHODS: The treated group included 45 growing Class II, division 1, patients treated with stainless steel crown Herbst appliances, followed by fixed edgewise appliances. The untreated control group consisted of 45 Class II, division 1, subjects, matched to the treated sample based on Angle classification, age, sex, and pretreatment mandibular plane angle (MPA). Subjects were categorized as hypo- or hyperdivergent based on their MPAs. Pre- and posttreatment cephalograms were traced and superimposed on cranial base and mandibular structures. RESULTS: The primary effect of the Herbst in terms of maxillomandibular correction was in the maxilla. It significantly restricted maxillary growth, producing a "headgear effect." Mandibular treatment changes depended on divergence. Hyperdivergent patients experienced a deleterious backward true mandibular rotation with Herbst treatment. Hypodivergent patients, as well as untreated hypo- and hyperdivergent controls, underwent forward true mandibular rotation. However, hypodivergent chins did not advance any more than expected for untreated hypodivergent Class II patients. CONCLUSIONS: Hypo- and hyperdivergent patients benefit from the Herbst's headgear effect. While the mandibular growth of hypodivergent patients overcomes the negative rotational effects, hyperdivergent patients undergo a deleterious backward mandibular rotation and increases in facial height.

Reliability and validity of FluoreCam for white-spot lesion detection: An in vitro study.

AIM: In the present study, we tested the reliability and validity of a new light fluorescence device, the FluoreCam. METHODS: Twenty-five human teeth were sectioned mesiodistally into halves. Group 1 (n=30) included specimens with either sound enamel or natural white-spot lesions (WSL). Group 2 (n=20) included specimens with sound enamel used to create artificial WSL. Using the FluoreCam, baseline scans of enamel surfaces were obtained under standardized conditions. Group1 was scanned again the next day. Group 2 specimens were covered with an acid-resistant nail polish, leaving a 2 × 6-mm enamel window exposed, immersed in Queiroz-solution (64 hours, 37°C/pH5 with agitation), and then scanned again. Random error of the repeated measurements (reliability) was determined using method errors and intraclass correlations (ICC). Systematic error and the ability to detect demineralization (validity) were tested using Wilcoxon signed-rank test. RESULTS: Method errors for Group 1 replicates were .39 mm2 (area), .72 pixels (intensity), and 5.69 pixels.mm2 (impact). Group 2 method errors were consistently slightly higher than those of group 1. FluoreCam showed highly reliable measurements for group 1 (ICC: 0.93-0.98) and group 2 (ICC: 0.87-0.97). There were no statistically-significant systematic errors for either group (P>.05). In group 2, enamel demineralization was statistically significant in area (P<.001), intensity (P=.001), and impact (P<.001). CONCLUSION: FluoreCam is highly reliable and valid for in vitro assessments of enamel demineralization.

Comparative study of two chemical protocols for creating white spot lesions: An in vitro FluoreCam evaluation.

AIM: The aim of the present study was to compare the effectiveness and practicality of two commonly-used protocols for white spot lesion creation. METHODS: Sound posterior human teeth were sectioned into halves and randomly allocated into two groups (n=20). Using the FluoreCam system, the enamel surfaces were imaged under standardized conditions, and baseline data (area, intensity, and impact) were recorded. Specimens were covered with an acid-resistant polish, leaving a 2×6-mm enamel window. Group 1 was immersed in Queiroz solution (64 hours/37°C/pH5 with agitation); Group 2 was immersed in Buskes solution (14 days/37°C/pH5 with agitation). The specimens then were imaged again. Within-group changes that occurred over time were evaluated using the Wilcoxon signed-rank test. Between-group differences were analyzed using the Mann-Whitney U-test. Polarized light microscopy (PLM) was used to calculate the mean lesion depth of representative specimens. RESULTS: Each protocol showed significant changes in the surface area, intensity and impact of demineralization over time (P<.05). There were no statistically-significant differences (P=.53, P=.2, P=.74) between the two groups. PLM showed that the mean lesion depths of representative specimens were 51.4 and 73.0 µm for groups 1 and 2, respectively. CONCLUSIONS: While both protocols produce similar amounts of demineralization, the Queiroz solution is more practical, as it requires less time.

Discomfort associated with Invisalign and traditional brackets: A randomized, prospective trial.

OBJECTIVE: To evaluate differences in discomfort levels between patients treated with aligners and traditional fixed orthodontic appliances. MATERIALS AND METHODS: This blinded, prospective, randomized equivalence two-arm parallel trial allocated 41 adult Class I nonextraction patients to either traditional fixed appliance (6 males and 12 females) or aligner (11 males and 12 females) treatment. Patients completed daily discomfort diaries following their initial treatment appointment, after 1 month and after 2 months. They recorded their levels of discomfort at rest, while chewing, and while biting, as well as their analgesic consumption and sleep disturbances. RESULTS: Both treatment modalities demonstrated similar levels of initial discomfort. There were no significant sex differences. Patients in the traditional fixed appliances group reported significantly (P < .05) greater discomfort than patients in the aligner group during the first week of active treatment. There was significantly more discomfort while chewing than when at rest. Traditional patients also reported significantly more discomfort than aligner patients after the first and second monthly adjustment appointments. Discomfort after the subsequent adjustments was consistently lower than after the initial bonding or aligner delivery appointments. A higher percentage of patients in the fixed-appliance group reported taking analgesics during the first week for dental pain, but only the difference on day 2 was statistically significant. CONCLUSIONS: Patients treated with traditional fixed appliances reported greater discomfort and consumed more analgesics than patients treated with aligners. This trial was not registered.

Elevation of a full-thickness mucoperiosteal flap alone accelerates orthodontic tooth movement.

INTRODUCTION: Our objective was to determine whether the elevation of a full-thickness mucoperiosteal flap alone, without cortical cuts, decreases the amount of bone around teeth and accelerates mesial tooth movements. METHODS: The mandibular second premolars of 7 beagle dogs were extracted, and on a randomly selected side, a full-thickness mucoperiosteal buccal flap extending from the distal aspect of the third premolar to the mesial aspect of the first premolar was elevated. The other side did not receive flap surgery. The mandibular third premolars were protracted with orthodontic appliances. Tooth movements were analyzed biweekly over an 8-week period with calipers and radiographs. The amount and density of bone were analyzed using microcomputed tomography; bone remodeling was evaluated with histologic sections. RESULTS: Experimental tooth movements measured intraorally between cusp tips were significantly greater (25.3%) than control tooth movements. The approximate center of resistance measured radiographically also moved significantly more (about 31%) on the experimental than on the control side. The experimental premolar tipped more than the control premolar (10.5° vs 8.7°), but the difference was not statistically significant. The medullary bone volume fraction mesial to the third premolar was significantly less (9.1%) and the bone was significantly less dense (9%) on the experimental side than on the control side. Histology showed no apparent side differences in the numbers of osteoclasts and osteoblasts evident in the medullary bone. CONCLUSIONS: Elevation of a full-thickness mucoperiosteal flap alone (ie, without injury to bone) decreases the amount and density of medullary bone surrounding the tooth and accelerates tooth movement. Due to its limited effects, elevation of a flap alone to increase tooth movements may not be justified.