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Background: Plantar fasciitis is a painful tendinous condition (tendinopathy) with a high prevalence in athletes. While a healthy tendon has limited blood flow, ultrasound has indicated elevated blood flow in tendinopathy, but it is unknown if this is related to a de facto increase in the tendon vasculature. Likewise, an accumulation of glycosaminoglycans (GAGs) is observed in tendinopathy, but its relationship to clinical pain is unknown., Purpose: To explore to what extent vascularization, inflammation, and fat infiltration were present in patients with plantar fasciitis and if they were related to clinical symptoms., Study Design: Descriptive laboratory study., Methods: Biopsy specimens from tendinopathic plantar fascia tissue were obtained per-operatively from both the primary site of tendon pain and tissue swelling ("proximal") and a region that appeared macroscopically healthy at 1 to 2 cm away from the primary site ("distal") in 22 patients. Biopsy specimens were examined with immunofluorescence for markers of blood vessels, tissue cell density, fat infiltration, and macrophage level. In addition, pain during the first step in the morning (registered during an earlier study) was correlated with the content of collagen and GAGs in tissue., Results: High vascularization (and cellularity) was present in both the proximal (0.89%) and the distal (0.96%) plantar fascia samples, whereas inconsistent but not significantly different fat infiltration and macrophage levels were observed. The collagen content was similar in the 2 plantar fascia regions, whereas the GAG content was higher in the proximal region (3.2% in proximal and 2.8% in distal; P = .027). The GAG content in the proximal region was positively correlated with the subjective morning pain score in the patients with tendinopathy (n = 17)., Conclusion: In patients with plantar fasciitis, marked tissue vascularization was present in both the painful focal region and a neighboring nonsymptomatic area. In contrast, the accumulation of hydrophilic GAGs was greater in the symptomatic region and was positively correlated with increased clinical pain levels in daily life., Clinical Relevance: The accumulation of GAGs in tissue rather than the extent of vascularization appears to be linked with the clinical degree of pain symptoms of the disease., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

The myotendinous junction (MTJ) is a specialized domain of the multinucleated myofibre that is faced with the challenge of maintaining robust cell-matrix contact with the tendon under high mechanical stress and strain. Here, we profiled 24,124 nuclei in semitendinosus muscle-tendon samples from three healthy males by using single-nucleus RNA sequencing (snRNA-seq), alongside spatial transcriptomics, to gain insight into the genes characterizing this specialization in humans. We identified a cluster of MTJ myonuclei represented by 47 enriched transcripts, of which the presence of ABI3BP, ABLIM1, ADAMTSL1, BICD1, CPM, FHOD3, FRAS1 and FREM2 was confirmed at the MTJ at the protein level in immunofluorescence assays. Four distinct subclusters of MTJ myonuclei were apparent, comprising two COL22A1-expressing subclusters and two subclusters lacking COL22A1 expression but with differing fibre type profiles characterized by expression of either MYH7 or MYH1 and/or MYH2. Our findings reveal distinct myonuclei profiles of the human MTJ, which represents a weak link in the musculoskeletal system that is selectively affected in pathological conditions ranging from muscle strains to muscular dystrophies., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

The myotendinous junction (MTJ) is structurally specialized to transmit force. The highly folded muscle membrane at the MTJ increases the contact area between muscle and tendon and potentially the load tolerance of the MTJ. Muscles with a high content of type II fibers are more often subject to strain injury compared with muscles with type I fibers. It is hypothesized that this is explained by a smaller interface area of MTJ in type II compared with type I muscle fibers. The aim was to investigate by confocal microscopy whether there is difference in the surface area at the MTJ between type I and II muscle fibers. Individual muscle fibers with an intact MTJ were isolated by microscopic dissection in samples from human semitendinosus, and they were labeled with antibodies against collagen XXII (indicating MTJ) and type I myosin (MHCI). Using a spinning disc confocal microscope, the MTJ from each fiber was scanned and subsequently reconstructed to a 3D-model. The interface area between muscle and tendon was calculated in type I and II fibers from these reconstructions. The MTJ was analyzed in 314 muscle fibers. Type I muscle fibers had a 22% larger MTJ interface area compared with type II fibers (p < 0.05), also when the area was normalized to fiber diameter. By the new method, it was possible to analyze the structure of the MTJ from a large number of human muscle fibers. The finding that the interface area between muscle and tendon is higher in type I compared with type II fibers suggests that type II fibers are less resistant to strain and therefore more susceptible to injury., (© 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Mechanical inputs give rise to p38 and JNK activation, which mediate adaptive physiological responses in various tissues. In skeletal muscle, contraction-induced p38 and JNK signaling ensure adaptation to exercise, muscle repair, and hypertrophy. However, the mechanisms by which muscle fibers sense mechanical load to activate this signaling have remained elusive. Here, we show that the upstream MAP3K ZAKβ is activated by cellular compression induced by osmotic shock and cyclic compression in vitro, and muscle contraction in vivo. This function relies on ZAKβ's ability to recognize stress fibers in cells and Z-discs in muscle fibers when mechanically perturbed. Consequently, ZAK-deficient mice present with skeletal muscle defects characterized by fibers with centralized nuclei and progressive adaptation towards a slower myosin profile. Our results highlight how cells in general respond to mechanical compressive load and how mechanical forces generated during muscle contraction are translated into MAP kinase signaling., (© 2022 The Authors. Published under the terms of the CC BY NC ND 4.0 license.)

The myotendinous junction (MTJ), a specialized interface for force transmission between muscle and tendon, has a unique transcriptional activity and is highly susceptible to muscle strain injury. Eccentric exercise training is known to reduce this risk of injury, but knowledge of the influence of exercise on the MTJ at the molecular and cellular levels is limited. In this study, 30 subjects were randomized to a single bout of eccentric exercise 1 week prior to tissue sampling (exercised) or no exercise (control). Samples were collected from the semitendinosus as part of reconstruction of the anterior cruciate ligament and divided into fractions containing muscle, MTJ and tendon, respectively. The concentrations of macrophages and satellite cells were counted, and the expression of genes previously known to be active at the MTJ were analyzed by real-time-quantitative PCR. An effect of the single bout of exercise was found on the expression of nestin (NES) and osteocrin (OSTN) mRNA in the MTJ and tendon fractions. Genes earlier identified at the MTJ (COL22A1, POSTN, ADAMTS8, MNS1, NCAM1) were confirmed to be expressed at a significantly higher level in the MTJ compared to muscle and tendon but were unaffected by exercise. In the exercise group a higher concentration of macrophages, but not of satellite cells, was seen in muscle close to the MTJ. The expression of NES and OSTN was higher in human semitendinosus MTJ 1 week after a single session of heavy eccentric exercise. Based on these results, NES and OSTN could have a part in explaining how the MTJ adapts to eccentric exercise., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Proteomics analysis of skeletal muscle has recently progressed from whole muscle tissue to single myofibers. Here, we further focus on a specific myofiber domain crucial for force transmission from muscle to tendon, the myotendinous junction (MTJ). To overcome the anatomical constraints preventing the isolation of pure MTJs, we performed in-depth analysis of the MTJ by progressive removal of the muscle component in semitendinosus muscle-tendon samples. Using detergents with increasing stringency, we quantified >3000 proteins across all samples, and identified 112 significantly enriched MTJ proteins, including 24 known MTJ-enriched proteins. Of the 88 novel MTJ markers, immunofluorescence analysis confirmed the presence of tetraspanin-24 (CD151), kindlin-2 (FERMT2), cartilage intermediate layer protein 1 (CILP), and integrin-alpha10 (ITGA10), at the human MTJ. Together, these human data constitute the first detailed MTJ proteomics resource that will contribute to advance understanding of the biology of the MTJ and its failure in pathological conditions., Competing Interests: The authors declare no conflicts of interest., (© 2022 The Author(s).)

Insight into the bidirectional signaling between primary human myogenic cells and neurons is lacking. For this purpose, human myogenic cells were derived from the semitendinosus and gracilis muscles of five healthy individuals and co-cultured with cerebellar granule neurons from two litters of 7-day-old Wistar rat pups, in muscle medium or neural medium, alongside monocultures of myogenic cells or neurons. RT-PCR was performed to determine human mRNA levels of GAPDH, Ki67, myogenin, and MUSK, and the acetylcholine receptor subtypes CHRNA1, CHRNB1, CHRNG, CHRND, and CHRNE, and rat mRNA levels of GAPDH, Fth1, Rack1, vimentin, Cdh13, and Ppp1r1a. Immunocytochemistry was used to evaluate neurite outgrowth (GAP43) in the presence and absence of myogenic cells. Co-culture with primary neurons lead to higher myogenic cell gene expression levels of GAPDH, myogenin, MUSK, CHRNA1, CHRNG, and CHRND, compared to myogenic cells cultured alone. It appeared that neurons preferentially attached to myotubes and that neurite outgrowth was enhanced when neurons were cultured with myogenic cells compared to monoculture. In neural medium, rat mRNA levels of GAPDH, vimentin, Cdh13, and Ppp1r1a were greater in co-culture, versus monoculture, whereas in muscle medium co-culture lead to lower levels of Fth1, Rack1, vimentin, and Cdh13 than monoculture. These findings demonstrate mutually beneficial stimulatory signaling between rat cerebellar granule neurons and human myogenic cells, providing support for an active role for both the neuron and the muscle cell in stimulating neurite growth and myogenesis. Bidirectional muscle nerve signaling., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

The myotendinous junction (MTJ) is a specialized interface for transmitting high forces between the muscle and tendon and yet the MTJ is a common site of strain injury with a high recurrence rate. The aim of this study was to identify previously unknown MTJ components in mature animals and humans. Samples were obtained from the superficial digital flexor (SDF) muscle-tendon interface of 20 horses, and the tissue was separated through a sequential cryosectioning approach into muscle, MTJ (muscle tissue enriched in myofiber tips attached to the tendon), and tendon fractions. RT-PCR was performed for genes known to be expressed in the three tissue fractions and t-distributed stochastic neighbor embedding (t-SNE) plots were used to select the muscle, MTJ, and tendon samples from five horses for RNA sequencing. The expression of previously known and unknown genes identified through RNA sequencing was studied by immunofluorescence on human hamstring MTJ tissue. The main finding was that RNA sequencing identified the expression of a panel of 61 genes enriched at the MTJ. Of these, 48 genes were novel for the MTJ and 13 genes had been reported to be associated with the MTJ in earlier studies. The expression of known [COL22A1 (collagen XXII), NCAM (neural cell adhesion molecule), POSTN (periostin), NES (nestin), OSTN (musclin/osteocrin)] and previously undescribed [MNS1 (meiosis-specific nuclear structural protein 1), and LCT (lactase)] MTJ genes was confirmed at the protein level by immunofluorescence on tissue sections of human MTJ. In conclusion, in muscle-tendon interface tissue enriched with myofiber tips, we identified the expression of previously unknown MTJ genes representing diverse biological processes, which may be important in the maintenance of the specialized MTJ.

The incidence of strain injuries continues to be high in many popular sports, especially hamstring strain injuries in football, despite a documented important effect of eccentric exercise to prevent strains. Studies investigating the anatomical properties of these injuries in humans are sparse. The majority of strains are seen at the interface between muscle fibers and tendon: the myotendinous junction (MTJ). It has a unique morphology with a highly folded muscle membrane filled with invaginations of collagen fibrils from the tendon, establishing an increased area of force transmission between muscle and tendon. There is a very high rate of remodeling of the muscle cells approaching the MTJ, but little is known about how the tissue adapts to exercise and which structural changes heavy eccentric exercise may introduce. This review summarizes the current knowledge about the anatomy, composition and adaptability of the MTJ, and discusses reasons why strain injuries can be prevented by eccentric exercise., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Jakobsen and Krogsgaard.)

Purpose: Frozen shoulder is characterized by pain and reduced passive movement capability, and the diagnose is made clinically. However, pain is the major symptom in the first stage before stiffness occurs, and the condition can be mistaken for subacromial impingement. This study explored the possibility to use positron emission tomography/computed tomography (PET/CT) with a 18 F Flour-Deoxy-Glucose (FDG) tracer in the diagnostic process., Methods: Eleven patients with frozen shoulder and 9 patients with subacromial impingement received a 18 F-FDG PET/CT scan before being treated surgically. During arthroscopy, the diagnoses were confirmed. Images were blindly analyzed visually by two nuclear medicine physicians. Also, semi-quantified analysis applying a set of standard regions was performed, and standard uptake value in both shoulder regions was recorded., Results: Both the visual description of the pictures and the semi-quantified analysis generally showed increased FDG uptake in the affected shoulder regions of patients that had frozen shoulder and no uptake in patients with subacromial impingement. Kappa for interobserver agreement in the visual assessments was 0.74. Sensitivity was 92% and specificity 93% of the visual assessment, 77% and 93%, respectively, of the semi-quantified analyses, and by combining the two types of analyses sensitivity was 100% and specificity was 93% for the distinction between frozen shoulders and subacromial impingement/unaffected shoulders., Conclusion: 18 F-FDG PET/CT seems to be a valid method to diagnose frozen shoulder. This is clinically relevant in diagnostically challenging cases, for instance in the first phase of frozen shoulder, which can be difficult to distinguish from subacromial impingement., Level of Evidence: II.

The myotendinous junction (MTJ) is at high risk of strain injuries, due to high amounts of energy that is transferred through this structure. The risk of strain injury is significantly reduced by heavy resistance training (HRT), indicating a remodeling capacity of MTJ. We investigated the degree of remodeling of muscle fibers near the human MTJ. In 8 individuals, samples were taken from the semitendinosus and gracilis MTJ and they were stained immunohistochemically for myonuclei (DAPI), fibroblasts (TCF7L2), and satellite cells (CD56). A high portion of the muscle fibers adjacent to the MTJ contained a centrally located myonucleus (47 ± 8%, mean ± SD) and half of the muscle fibers were CD56 positive. The number of satellite cells and fibroblasts were not higher than what has previously been reported from muscle bellies. The immunohistochemical findings suggest that the rate of remodeling of muscle fibers near the MTJ is very high. The finding that there was no increased number of satellite cells and fibroblasts could be explained as a dynamic phenomenon. The effect of HRT should be evaluated in a randomized setting., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The myotendinous junction (MTJ) is a common site of strain injury and yet understanding of its composition and ability to adapt to loading is poor. The main aims of this study were to determine the profile of selected collagens and macrophage density in human MTJ and adjoining muscle fibers, and to investigate whether heavy exercise loading would alter this profile. Fifteen individuals scheduled for anterior cruciate ligament repair surgery were randomized into three groups: control, acute or 4 weeks heavy resistance training. MTJ samples were collected from the semitendinosus and gracilis muscles and were sectioned and stained immunohistochemically for collagen types I, III, VI, XII, XIV, XXII, Tenascin-C and CD68. Macrophage density and distribution was evaluated and the amount of each collagen type in muscle and MTJ was graded. Collagen XXII was observed solely at the MTJ, while all other collagens were abundant at the MTJ and in muscle perimysium or endomysium. The endomysial content of collagen XIV, macrophages and Tenascin-C increased following 4 weeks of training. These findings illustrate the heterogeneity of collagen type composition of human MTJ. The increase in collagen XIV following 4 weeks of training may reflect a training-induced protection against strain injuries in this region., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Through an analysis of alliances between secular and religious actors in US politics and a specific case study on anti-trafficking policy, we show that the intertwining of religion and politics in the US comes from two sources: 1) the secular political and cultural institutions of American public life that have developed historically out of Protestantism, and which predominantly operate by presuming Protestant norms and values; and 2) the direct influence on US politics of religious groups and organisations, particularly in the past quarter-century of lobby groups and political action committees identified with conservative evangelical Christianity. The sources of policies that promote gender and sexual inequality in the US are both secular and religious and we conclude that it is inaccurate to assume that religious influence in politics is necessarily conservative or that more secular politics will necessarily be more progressive than the religious varieties.

Objective: To test the hypothesis that there is no difference between adults with Class I crowded (CICR), Class III (CIII), and Class I normal (CIN) occlusions with respect to (1) arch widths, (2) width of the maxillary and mandibular arches, (3) gender dimorphism within groups, and (4) gender comparisons., Materials and Methods: Samples of 39 CICR subjects, 40 CIII subjects, and 40 CIN subjects were studied. All subjects were white Americans with no history of orthodontic treatment. An analysis of variance and Duncan's test statistically compared the groups and genders., Results: The CICR group had mean maxillary and mandibular intermolar and alveolar arch widths significantly smaller than the CIN group. The CIII group had mean maxillary intermolar and alveolar arch widths significantly smaller than the CIN group. Mean maxillary and mandibular intercanine arch widths were similar in the three groups. The CICR and CIN groups had similar mean maxillary/mandibular intermolar and alveolar differences significantly larger than the negative differences observed in the CIII group. Gender dimorphisms were identical in the CIII and CIN groups. The CICR group differed by not having a gender dimorphism in the maxillary alveolar width and having a gender dimorphism in the mandibular intercanine width. Gender comparisons between groups were similar in intercanine widths but differed in other widths., Conclusions: The hypothesis was rejected by the findings of this study.

Aim: To determine the individual variation in the maxillary and mandibular tooth-size/arch-length relationships after the complete eruption of the primary dentition (mean age, 4.0 years) and at the time of eruption of the second permanent molars (mean age, 13.3 years)., Methods: Records of 32 males and 27 females were evaluated. Each subject had a clinically acceptable occlusion; that is, a normal molar and canine relationship at the time of eruption of the primary and permanent teeth. In addition, each subject had a complete set of data at the 2 stages of dental development. These selection criteria limited the number of subjects in this investigation to 59. The mesiodistal diameter of all primary teeth and their permanent successors, as well as various dental arch length parameters were measured in the primary and permanent dentitions. A total of 60 parameters were measured or calculated., Results: The findings from the present investigation indicated that of the total sample of 59 male and female subjects observed on a longitudinal basis, 29 (49%) maintained their relative tooth-size/arch-length relationship ranking in the 2 dentitions, while 30 (51%) changed to either a more favorable or less favorable relationship in the permanent dentition., Conclusions: The cases with the lower ranking of tooth-size/arch-length relationship in the primary dentition, 50% maintained their relatively lower rank in the permanent dentition, while the other 50% changed to a relatively more favorable rank in the permanent dentition. There is a similar probability for maintaining the same ranking in the primary and permanent dentitions in the mandibular arch (51%), as in the maxillary arch (49%). The clinical implications of the findings are discussed.

The purpose of this in vitro study was to compare fluoride ion release from 3 orthodontic bracket adhesives with and without brushing the bracketed teeth with a fluoridated dentifrice. The bracket adhesives included a light-cured composite resin (Transbond; 3M Unitek, Monrovia, Calif), a fluoride-releasing composite resin (Advance; L D Caulk Division, Dentsply International, Milford, Del), and a resin-modified glass ionomer (Fuji Ortho LC; GC America, Alsip, Ill). The teeth in the control group were not bonded with brackets. Sixty extracted human teeth were randomly assigned to 6 groups of 10 each: (1) Transbond, brushed; (2) Advance, brushed; (3) Advance, not brushed; (4) Fuji, brushed; (5) Fuji, not brushed; and (6) control, brushed. After bonding, each tooth was placed in a sealed plastic test tube containing 4 ml of deionized water. The toothpaste used in brushing contained 0.15% weight per volume sodium fluoride, 1500 parts per million parts fluoride (Winter-fresh gel; Colgate-Palmolive Co., New York, NY). Brushing began 24 hours after the teeth were bonded and placed in deionized water. After brushing, the teeth were thoroughly rinsed with deionized water and returned to a sealed test tube. Fluoride measurements were taken before brushing began, at intervals of 72 hours for 22 days, and 90 and 93 days after bonding. Findings included: (1) brushing significantly increased the release of fluoride ions from the teeth in the composite resin and control groups, (2) the enamel crowns of the unbonded control teeth absorbed and re-released a substantial amount of fluoride ions obtained from the toothpaste, (3) the brushed group of teeth bonded with the fluoride-releasing composite resin released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, (4) the brushed group of teeth bonded with the resin-modified glass ionomer released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, and (5) all groups released small amounts of fluoride ions 90 and 93 days after bonding (68.5 and 71.5 days after brushing ended); the resin-modified glass ionomer groups released significantly more fluoride than the other groups. Brushing with fluoridated toothpaste produced significantly greater fluoride release from teeth bonded with all 3 adhesives, and from the unbonded control teeth.

Far too often a less-than-optimal esthetic result occurs after orthodontic treatment due to demineralization of enamel adjacent to fixed orthodontic appliances in patients with inadequate oral hygiene. In vitro studies have shown that a resin-modified glass ionomer (RMGI) cement and a fluoride varnish might help clinicians combat this problem. The purpose of this study was to evaluate, in vitro, the effect of a fluoride-releasing cavity varnish on inhibition of enamel demineralization adjacent to orthodontic brackets bonded with RMGI and composite resin cements. Brackets were bonded to 48 extracted human third molars. Half were bonded with a composite resin (Transbond, 3M Unitek, Monrovia, Calif) and half with an RMGI (Fuji Ortho LC, GC America, Alsip, Ill). Each group was further divided into 2, with half receiving an application of fluoride-releasing varnish (Duraflor, Pharmascience, Montreal, Québec, Canada). The samples were cycled in an artificial caries solution for an hour twice daily for 31 days. After each caries challenge, the teeth were brushed with a soft toothbrush to simulate normal mechanical wear of the varnish. The loss of fluoride varnish was timed. Teeth were sectioned longitudinally and photographed under polarized light microscopy. Mean lesion depth was measured, and analysis of variance (ANOVA) (P

In recent years, some researchers have proposed that the depth of the mandibular antegonial notch can be used as a predictor of facial growth. However, the data for those studies were derived from populations with extreme morphologic characteristics. The purpose of this investigation was to test the hypothesis that the antegonial notch depth is a useful predictor of facial growth in a longitudinal sample of untreated growing patients selected at random. Lateral cephalometric radiographs were obtained from 20 males and 20 females at 3 times, approximating prepubescence (8.5 years), adolescence (12 years), and adulthood (> or = 17 years). These 40 subjects were randomly chosen from a longitudinal sample of untreated growing patients. Prepubescent and adolescent antegonial notch depths were correlated with vertical and horizontal growth changes of the jaws from the age of 8.5 years to adulthood. Correlation analysis revealed a statistically (but not clinically) significant negative relationship (0.40 < or = r < or = 0.47; P < or =.05) between adolescent antegonial notch depth and horizontal growth of the maxilla and the mandible from adolescence to adulthood. Previous investigators have proposed that antegonial notch depth, when extreme in magnitude, might be used to predict facial growth. We concluded that antegonial notch depth fails to provide sufficient indication of future facial growth to warrant its application as a growth predictor in a nonextreme population.

The cleanup of remnant bonding adhesive from the enamel surface after debonding is an important factor for clinicians. The purposes of this study were to compare the weight, the surface area, and the cleanup times of remnant adhesive for a composite resin, Transbond (TB); a resin-modified glass ionomer, Fuji ORTHO LC bonded to enamel both conditioned (FOC) and nonconditioned (FONC); and a fluoride-releasing composite resin, Advance (ADV), bonded to nonetched enamel. In addition, 2 qualitative methods for scoring remnant adhesive were compared with the quantitative weight and area data. Forty extracted human incisors were weighed, bonded with brackets, debonded, weighed, and photographed. Area was measured from the photographs with a sonic digitizer. Mean adhesive remnant weights differed between groups (analysis of variance [ANOVA], P =.02): The remnants from ADV and FOC were equal and both significantly heavier than the remnants from FONC; the weights of the TB remnants were intermediate between the heavier ADV and FOC remnants and the lighter FONC remnants. Mean remnant areas differed between groups (ANOVA, P =.03): The remnants from ADV were significantly larger than the remnants from TB and FONC, which were equal; the areas of the FOC remnants were intermediate between the larger ADV remnants and the smaller remnants from TB and FONC. Mean cleanup times also differed between groups (ANOVA, P <.001): TB and FOC had equal times that were significantly longer than the times for ADV and FONC, which were equal. Adhesives bonded to acid-etched or conditioned enamel took about 1 and a half times longer to clean up than did those bonded to nonetched enamel. When bonded to conditioned enamel, the resin-modified glass ionomer had mean remnant adhesive weights, areas, and cleanup times statistically equivalent to TB. ADV had the fastest mean cleanup time per amount of remnant (ANOVA, P <.002). The graphs of scores for 2 qualitative methods used for scoring remnant amount did not closely resemble the graphs based on weight and area. The graph of a newly introduced qualitative method better reflected the area data. Weighing may be a useful method for quantifying remnant adhesive.

Objectives: Several studies have assessed people's esthetic perceptions of dental fluorosis, suggesting that concerns may be greater than believed previously. Few studies have assessed dental students' perceptions and none has done so over time. The purpose of this paper is to report on changes in dental students' esthetic perceptions of dental fluorosis and other conditions., Methods: Fourth-year dental students (n=45) completed questionnaires about computer-generated photographs of fluorosis and other conditions, using the same protocol as when they were entering dental students. Results were compared for each of the eight images at the individual level using paired statistical tests., Results: Although many patterns were generally consistent, there were a substantial number of differences in results over time, concerning both the mild fluorosis and non-fluorosis images. In general, students tended to score both fluorosis and non-fluorosis images more favorably as fourth-year students. When rating images from very pleased (1) to very embarrassed (10), fourth-year students rated the images significantly more favorably than they had done as first-year students for normal/control, incisal third only dental fluorosis, and a more generalized, mild fluorosis. Similarly, with a visual analog scale from satisfactory (0) to unsatisfactory (69), fourth-year students reported significantly lower (more favorable) scores than they had done as first-year students for the normal/control, diastema/no fluorosis, more involved mild fluorosis, and incisal third only mild fluorosis. There were no obvious changes in the relative levels of favorable evaluation of fluorosis vs. the other conditions., Conclusions: Fourth-year dental students generally had more favorable esthetic perceptions of mild dental fluorosis and other conditions than they had reported as entering students.

The control of pain during orthodontic treatment is of vital interest to both clinicians and patients. Surprisingly, there has been limited research into the control of orthodontic pain, and there is no standard of care for controlling this discomfort. The purpose of this study was to compare the effectiveness of preemptive ibuprofen therapy, postoperative ibuprofen therapy, and a combination of the 2 therapies. Forty-one orthodontic patients aged 9 years 3 months to 16 years 11 months who were to undergo separator placement were enrolled in this prospective study. Patients were randomly assigned to 1 of 3 experimental conditions: (1) 400 mg ibuprofen taken orally 1 hour before separator placement and 400 mg ibuprofen taken orally 6 hours after the initial dose, (2) 400 mg ibuprofen taken orally 1 hour before separator placement and a lactose capsule taken orally 6 hours after the initial dose, or (3) a lactose capsule taken orally 1 hour before separator placement and 400 mg ibuprofen taken 6 hours after the initial placebo. The results revealed that preemptive ibuprofen therapy significantly decreased pain that was experienced 2 hours after separator placement and at bedtime. Beginning on day 2, there was a trend for patients who had taken both preemptive and postoperative ibuprofen doses to have lower pain scores compared with the other 2 groups. In conclusion, these data indicate that ibuprofen taken 60 minutes before separator placement alleviates pain at 2 hours and at bedtime after treatment. Further study with the use of additional postoperative doses is warranted.

Patients undergoing orthodontic treatment can experience significant levels of pain. This study assessed the effectiveness of preoperative ibuprofen in reducing the incidence and the severity of pain after orthodontic separator placement. Sixty-three adolescent patients (mean age, 13 years) were included in this randomized, double-blind, placebo-controlled, prospective study. Patients were randomly assigned to 1 of 3 experimental conditions: (1) 400 mg of ibuprofen taken orally 1 hour before separator placement and a lactose placebo taken orally immediately after the appointment, (2) a lactose placebo taken orally 1 hour before separator placement and 400 mg of ibuprofen taken orally immediately after the appointment, or (3) a lactose placebo taken orally 1 hour before separator placement and again immediately after the appointment. The patient's level of discomfort was assessed with a visual analog scale at 2, 6, and 24 hours, as well as at 2, 3, and 7 days after placement of the orthodontic separators. An analysis of variance and Duncan's multiple range test revealed that 2 hours after their orthodontic appointment the patients who had taken ibuprofen 1 hour before separator placement had significantly less pain with chewing than did the patients who received either ibuprofen postoperatively or a placebo. Additional measures suggest a trend for less pain for this group of patients. These results support the use of pretreatment ibuprofen for patients requiring analgesics for orthodontic discomfort. Future study of the use of preemptive analgesics in orthodontics is warranted.

The purpose of this study was to determine the effects on shear bond strength of changing the concentration of the enamel conditioner used with resin-reinforced glass ionomer. Shear bond strength was measured within 30 minutes after bonding. Forty-six freshly extracted human molars were collected and stored in a solution of 0. 1% (weight/volume) thymol. The teeth were cleaned and polished, then randomly separated into 2 groups. In group I, enamel was conditioned with a 10% polyacrylic acid solution before bonding. In group II, the enamel was conditioned with a 20% polyacrylic acid solution. The results of t test comparisons of the 2 experimental groups (t = 4.9) indicate significant differences (P =.001). Shear bond strength was significantly greater in the group conditioned with the 20% polyacrylic acid concentration (X = 3.3 +/- 2.6 MPa) than in the group conditioned with the 10% concentration (X = 0.4 +/- 1.0 MPa). The present findings indicated that the lower initial shear bond strength of resin-reinforced glass ionomer adhesive can be improved more than 8-fold when the concentration of the polyacrylic acid enamel conditioner is increased from 10% to 20%. The clinician needs to take these properties into consideration when ligating the initial archwires.

The purpose of this study was to determine the effects of changing the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer within half an hour after bonding the bracket to the tooth. Freshly extracted human molars were collected and stored in a solution of 0.1% (weight/volume) thymol. The teeth were cleaned and polished. The teeth were randomly separated into 4 groups according to the enamel conditioner/etchant and adhesive used: group I, teeth were conditioned with 10% polyacrylic acid and brackets were bonded with a resin-reinforced glass ionomer adhesive; group II, teeth were conditioned with 20% polyacrylic acid and brackets were bonded with a resin-reinforced glass ionomer adhesive; group III, teeth were etched with 37% phosphoric acid and the brackets were bonded with a resin-reinforced glass ionomer adhesive; group IV, teeth were etched with 37% phosphoric acid and the brackets were bonded with a composite adhesive. The results of the analysis of variance comparing the 4 experimental groups (F = 24.87) indicated the presence of significant differences between the groups (P =.0001). In general, the shear bond strengths were significantly greater in the 2 groups etched with 37% phosphoric acid. This was true for both the resin-reinforced glass ionomer (X = 6.1 +/- 2.7 MPa) and the composite (X = 5.2 +/- 2.9 MPa) adhesives. On the other hand, the shear bond strengths were significantly lower in the two groups conditioned with polyacrylic acid. The bond strength of the resin-reinforced glass ionomer adhesive conditioned with 10% polyacrylic acid (X = 0.4 +/- 1.0 MPa) was significantly lower than the group conditioned with 20% polyacrylic acid (&xmacr; = 3.3 +/- 2.6 MPa). The present findings indicated that the bond strength of the resin-reinforced glass ionomer adhesive can be significantly increased in the initial half hour after bonding if the enamel is etched with 37% phosphoric acid instead of being conditioned with either 10% or 20% polyacrylic acid. The clinician needs to take these properties into consideration when ligating the initial archwires.

Our purpose was to investigate the impact of mandibular advancement surgery on profile esthetics and to attempt to define guidelines that could be of value to the clinician in predicting profile esthetic change. The sample consisted of 34 patients who had been treated with a combination of orthodontics and mandibular advancement surgery without genioplasty. Initial (pretreatment) and final (posttreatment) cephalometric radiographs of each patient were used to produce silhouette images and to quantify skeletal changes that occurred with surgery. The images were displayed randomly to lay persons and orthodontic residents who were asked to score the esthetics of each profile. On average, after mandibular advancement surgery, B point moved forward 5.0 mm (SD = 2.6 mm) and downward 4.7 mm (SD = 3.1 mm), and the ANB angle decreased 3.0 degrees (SD = 1.6 degrees ) Graphical analysis and results of paired t tests revealed that for patients with an initial ANB angle >/= 6 degrees, a consistent improvement in profile esthetics was seen following surgery (P

With the introduction of photosensitive (light-cured) restorative materials in dentistry, various methods were suggested to enhance the polymerization of these materials including layering and the use of more powerful light-curing devices. The purpose of this study was to determine the effects of increasing the light-cure time on the initial shear bond strength (in the first half hour) of a resin-modified glass-ionomer adhesive. Eighty-six teeth were divided into 4 groups according to either; (1) the adhesive system used, namely resin, reinforced glass ionomer, or composite, and (2) the light-cure time for the glass ionomer adhesive, namely 40, 45, and 50 seconds. The bonding approach followed the manufacturer's instructions unless otherwise specified. The results of the analysis of variance comparing the 4 experimental groups (F = 19.4) indicated the presence of significant differences between the groups (P =. 0001). In general, the shear bond strength was greater for the composite adhesive system (¿x(-) = 5.2 +/- 2.9 MPa), followed by the 2 groups bonded with the resin-reinforced glass-ionomer adhesive and light cured for 50 seconds (¿x(-) = 3.8 +/- 1.1 MPa) and 45 seconds (¿x(-) = 3.4 +/- 2.7 MPa). On the other hand, the shear bond strength was significantly lower for the group bonded with the glass ionomer adhesive and light cured for 40 seconds only (¿x(-) = 0.4 +/- 1.0 MPa). The present findings indicated the following: (1) the resin-reinforced glass-ionomer adhesive has a significantly lower shear bond strength in the first half hour after bonding when compared to a composite resin adhesive; (2) the initial bond strength of the glass-ionomer adhesive was significantly increased by increasing the light-cure time for an additional 5 to 10 seconds; (3) the mean increase in the shear bond strength between 5 and 10 seconds of additional light curing was not significant but the variability was less with the longer cure time.

Objectives: Few studies have considered people's opinions about the esthetics of dental fluorosis. Assessments of fluorosis esthetics can be confounded by differences in a number of clinical factors, including tooth shape, color, contour, and gingival status. This pilot study compared esthetic perceptions of mild fluorosis and other conditions using computer-generated images made from a base set of normal appearing teeth., Methods: Entering dental students (n = 61) completed questionnaires about four sets of paired photographs. Three sets consisted of fluorotic teeth (very mild to mild) versus other conditions (diastema, isolated enamel opacity, "normal"/control) and the other pair compared two presentations of mild fluorosis (generalized versus limited to incisal one-third). Six questions, both qualitative and quantitative, were asked about each pair of photographs., Results: Mild fluorosis was assessed less favorably than normal/control, midline diastema was less favorable than mild fluorosis, and mild fluorosis was less favorable than isolated opacity., Conclusions: This approach allows fluorosis to be better compared with other oral conditions because the images are standardized. Additional research with this method is warranted, including more variations in conditions, more comparisons, and other study populations.

In this new era of relationship-based care, involvement in treatment planning and goal setting is a high priority for patient satisfaction. This study reports on the use of standardized patients (SPs) in training third-year dental students to gather dental, medical, and psychosocial information from patients and to involve the patient in the decision-making process leading to the dental treatment plan. Among the skill areas measured, students were most successful in gathering dental information, with 94 percent of the students obtaining the complete set. Students were least successful in identifying the patient's goals for treatment (81 percent of the students identified the patients' goals). Students were most challenged by discussing sensitive topics with patients such as grief-related depression (25 percent of the students recognized and discussed such topics). It is important that dental schools familiarize students with patient issues and teach them how to talk effectively to patients about personal issues and to incorporate those issues into a discussion of the treatment plan for the patient. Standardized patients can be used effectively toward this end.

Two new ceramic brackets-one designed with a metal-lined arch wire slot and the other with an epoxy resin base-have been recently introduced. The new brackets are thought to combine the esthetic advantages of ceramics and the functional advantages of debonding metal brackets. The purpose of this study was to compare the following: 1) the shear bond strength of the 2 brackets, and 2) the bond failure location when the brackets are debonded with pliers. Sixty-one Clarity (3M Unitek) collapsible ceramic brackets and 66 MXi (TP Orthodontics, Inc) brackets were bonded to the teeth with the same bonding system. The Zwick Universal Test Machine (Zwick Gm bH & Co) was used to determine the shear bond strength force levels needed to debond the brackets. The appropriate pliers also were used to debond both types of brackets to determine the mode of bond failure that will be encountered clinically. After debonding, all the teeth and brackets were examined with 10x magnification. Any adhesive that remained after the bracket removal was assessed according to the Adhesive Remnant Index. The findings indicated that the shear bond strength of the Clarity ceramic brackets was significantly greater than that of the MXi ceramic brackets. However, both brackets exhibited forces that were adequate for clinical use. The Adhesive Remnant Index scores for both the shear test and the plier debonding indicated a similar bond failure pattern when the 2 ceramic brackets were compared with each other. This suggests that, when these brackets are debonded with the Weingart (Ormco) and ETM (Ormco) pliers, there was a greater tendency for most of the adhesive to remain on the enamel surface. In conclusion, the most efficient method to debond the MXi ceramic bracket is by placing the blades of the ETM 346 pliers between the bracket base and the enamel surface. On the other hand, the most efficient method of debonding the Clarity bracket is by using the Weingart pliers and applying pressure to the tiewings. When the 2 ceramic brackets were debonded as recommended here, most of the residual adhesive remained on the enamel surface, a pattern similar to the one observed previously with metal brackets. The failure at the bracket-adhesive interface decreases the probability of enamel damage but necessitates the removal of more residual adhesive after debonding.

A significant number of adults are seeking orthodontic treatment, therefore, it is important to determine the normal changes in root length (resorption or apposition) that occur at this stage of maturation, specifically between early and mid-adulthood. The purpose of the study was to determine on a longitudinal basis the changes in root length between 25 and 45 years of age in a normative untreated population. Two sets of complete mouth surveys were available at early and mid-adulthood, on a total of 26 subjects (12 males and 14 females). Each set consisted of at least 18 periapical radiographs. On each set of radiographs, the roots of 28 teeth were measured including incisors, canines, premolars, and first and second molars, in both the maxillary and mandibular arches. Root length was measured as the perpendicular from the root apex to a line connecting the mesial and distal points of the cementoenamel junction of each tooth. A total of 1456 teeth (1664 roots) were measured; 672 teeth in males and 784 teeth in females. Allowable intraexaminer and interexaminer measurement variability was predetermined at 0.5 mm. Paired and Student t tests were used to determine: (1) whether significant changes occurred with age; (2) whether there were differences between males and females for the incisors, canines, premolars, and molars; and (3) whether there were differences between the right and left sides. Statistical significance was predetermined at P

Objective: The purposes of this study were to examine the density correction afforded by curve-fitting algorithms and to investigate whether the device we developed significantly improves the reliability of longitudinal alveolar process bone radiographic density measurements., Study Design: Stepwedges were radiographed over a range of impulse settings, and curve-fitting algorithms were fitted to sets of step images on each digitized film. Differences between the actual thicknesses of an alternate set of steps and their corresponding thickness estimates were calculated. Next, clinicians made periapical radiographs from interproximal bony sites on a dry skull using our imaging device. Differences in bone densities between corresponding regions of interest taken 1 week apart were calculated., Results: Analysis of variance and Duncan's Multiple Range test demonstrated that piecewise linear, third-degree polynomial, and fourth-degree polynomial curves provided significantly better estimates of stepwedge thickness than did sigmoid or first degree polynomial-curves (P < .05) and that the differences between repeat bone density measurements made with density correction were significantly less than those made without density correction (P < .05)., Conclusions: Piecewise linear, third-degree polynomial, and fourth-degree polynomial curve-fitting algorithms provided the best densitometric correction. The use of our imaging device increased the reliability of longitudinal bone density measurements.

The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of three methods: (1) a glass ionomer adhesive with a 20% polyacrylic acid enamel conditioner; (2) a composite resin adhesive used with 37% phosphoric acid etchant and a conventional primer; or (3) the same composite resin used with an acidic primer that combines the etchant with the primer in one application. The brackets were bonded to the teeth according to one of three protocols. Group I teeth were etched with 37% phosphoric acid and bonded with Transbond XT (3M Unitek, Monrovia, Calif) following the manufacturer's instructions. Group I acted as the control group. Group II teeth were etched with an acidic primer (Clearfil Liner Bond 2. J.C. Moritta Kuraway, Japan) that contains both the acid (Phenyl-P) and the primer (HEMA and dimethacrylate) and was placed on the enamel for 30 seconds; the adhesive used to bond the brackets was Transbond XT as in Group I. Group III teeth were etched with 20% polyacrylic acid and the brackets were bonded with Fuji Bond LC (G.C. America, Chicago, Ill). A steel rod with one flattened end was attached to the crosshead of a Zwick test machine (Zwick GmbH & Co, Ulm, Germany). An occlusogingival load was applied to the bracket, producing a shear force at the bracket-tooth interface. The results indicated that the resin/phosphoric acid adhesive system (control group) provided the strongest shear bond strength x = 10.4 +/- 2.8 MPa). The glass ionomer adhesive system provided a significantly lower bond strength (x = 6.5 +/- 1.9 MPa). The least shear bond strength was present when the acidic primer was used with an orthodontic adhesive (x = 2.8 +/- 1.9 MPa). In the present study, the use of either a fluoride-releasing glass ionomer or an acidic primer in combination with an available orthodontic composite adhesive resulted in a significantly reduced shear bond strength when compared with that of the conventional composite resin adhesive system. At the present time, the orthodontist and the patient are better served by using phosphoric acid/composite resin adhesive system or other equivalent systems that provide a clinically reliable bond strength between the bracket, the adhesive, and the enamel surface.

The purpose of this study was to describe the changes in five soft tissue parameters that are commonly used by orthodontic practitioners in their diagnosis and treatment planning as well as in their evaluation of profile changes that occur with growth and orthodontic treatment. The subjects in this study were 20 males and 15 females for whom lateral cephalograms were available between 5 and 45 years of age. The parameters evaluated were two angles of facial convexity, the Holdaway soft tissue angle, and the relationship of the upper and lower lips to Rickett's esthetic line. Descriptive statistics for the absolute and incremental changes were collected on a yearly basis between 5 and 17 years of age as well as at early (25 years) and middle (45 years) adulthood. Growth profile curves were constructed for each parameter to describe the age-related changes in the five parameters for both males and females. The analysis of variance was used to compare the absolute and incremental changes both longitudinally and cross-sectionally. Significance was predetermined at P

The purpose of this investigation was to assess the method proposed by Skieller, Björk, and Linde-Hansen in 1984 to predict mandibular growth rotation. Our sample consisted of 40 randomly selected, untreated, adolescent subjects representative of the patient population generally encountered in orthodontic practice. The four independent variables identified in the Skieller study as having the highest predictive value (mandibular inclination, intermolar angle, shape of the lower border of the mandible, and inclination of the symphysis) were identified on initial lateral cephalograms. The proposed regression equations were applied and predicted mandibular rotations obtained. Final lateral cephalograms made 6 years after the initial profile radiographs were superimposed and actual mandibular rotation recorded. The observed and predicted rotations were compared and regression analyses performed to determine the amount of variability in observed values accounted for by the four variables individually and in combination. Only 5.6% of the variability in mandibular growth rotation could be accounted for using the four variables individually. Only 9% of the variability could be accounted for with a combination of the variables. In addition, we performed a Monte Carlo analysis, which mirrored the Skieller analysis but used random numbers instead of actual cephalometric data, to determine if the Skieller results may simply have capitalized on chance. Using the same forward stepwise selection procedure with a rejection level of P >.1, we found after 5000 simulations that a mean of 84% and a median of 94% of mandibular growth rotation variability could be accounted for using meaningless data in the Skieller analysis. This result was comparable to the Skieller value of 86%. In conclusion, information derived from pretreatment lateral cephalograms using the Skieller, Björk, and Linde-Hansen method does not permit clinically useful predictions to be made in a general population relative to the direction of future mandibular growth rotation.

The determination of the tooth size-arch length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. Three approaches have been used to estimate the mesiodistal crown widths of unerupted canines and premolars: (1) measurements from erupted teeth, (2) measurements from radiographs, and (3) a combination of measurements from erupted teeth and from radiographs of unerupted teeth. The purpose of this study was to compare two mixed dentition prediction methods that do not require the use of periapical radiographs of the unerupted permanent teeth. The two methods compared were the Tanaka/Johnston and the Boston University Prediction approaches. Records on 33 male and 22 female subjects who were participants in the Iowa Longitudinal Growth Study were used in the present study. The findings indicated that on the average the Tanaka/Johnston approach slightly overestimated the tooth size of the unerupted teeth (mean = 1.1 +/- 0.9 mm). On the other hand, the Boston University approach slightly underestimated the tooth size of the unerupted teeth (mean = -0.1 +/- 1.2 mm). The findings further indicated that there were statistically significant correlations between the predicted and actual tooth size. In general the r values were higher for the Tanaka/Johnston method than with the Boston University approach. The error involved in the use of the predicted equations was expressed as the standard error of the estimate. The present findings indicated that the standard error of the estimate for Tanaka/Johnston prediction equations ranged between 0.67 and 0.92 mm and the corresponding values for the Boston University equations ranged between 0.92 and 1.02 mm. Depending on the stage of dental development, i.e., which deciduous and permanent teeth are present, the Tanaka/Johnston approach can be used when the four mandibular incisors have completely erupted, whereas the Boston University approach can be used when all the deciduous canines and first molars are still present.

The purpose of this in vitro study was to answer the following questions for three different metal brackets: (1) when rebonding a previously bonded tooth, how do shear bond strengths compare for new brackets, new microetched brackets, and debonded microetcher cleaned brackets? and (2) how do the different bracket types compare with respect to the time required to remove composite resin from their bonding pads with a microetcher? Ninety human premolars and canines previously debonded of metal brackets were randomly assigned to 9 groups of 10 teeth each. New, new etched, and debonded etched cleaned brackets of each type were bonded with composite resin onto teeth, and the bonds tested to failure for shear bond strength. An analysis of variance and Duncan's multiple range test were used to compare bracket/enamel bond strength. Within each bracket type no significant differences were found between mean bond strengths for new, new etched, and debonded etched conditions, a finding that supports the use of microetching to clean accidentally debonded brackets. Mean times for removal of resin from bonding pads with a microetcher varied from 9.3 seconds to 11.9 seconds, with bracket (M) requiring significantly less time for removal of resin.

The purpose of this study was to compare a new light-cured bonding system that used a hybrid adhesive containing a resin reinforced glass ionomer (Fuji Ortho LC, GC America, Inc.) with a more traditional light-cured bonding system (Transbond, 3M Unitek) that contained resin material only. Seventy-five recently extracted human molars were collected and stored in a solution of 0.1% (weight/volume) thymol. The teeth were randomly separated into five groups of 15 molars each: Group I--using Transbond adhesive system with the enamel etched and dried before bonding. Group II--using Fuji Ortho LC (FOLC) adhesive system with no etch and the enamel wet with water before bonding. Group III--using FOLC adhesive system with the enamel etched and wet with water before bonding. Group IV--using FOLC adhesive system with no etch and the enamel wet with saliva before bonding. Group V--using FOLC adhesive system with the enamel etched and wet with saliva before bonding. The shear bond strength was performed after thermal cycling between 5 degrees +/- 2 degrees C and 50 degrees +/- 2 degrees C for a total of 2000 cycles with the Zwick test machine (Zwick Gm bH & Co.). After debonding, the teeth and brackets were examined under x10 magnification to evaluate the site of bond failure and the presence of residual adhesive. The analysis of variance was used to determine whether significant differences existed between the various groups. The findings indicated that there were no statistically significant differences among the three experimental groups I, III, and V that had the enamel surface etched before bonding, regardless of the adhesive used or the enamel surface contamination with water or saliva. On the other hand, the two experimental groups that did not have the enamel etched before bonding (II and IV) had significantly lower bond strengths. In conclusion, etching the enamel surface is a critical variable that affects shear bond strength as well as bond failure location when using the new adhesive system.

The purpose of this study was to evaluate changes in overbite over a 40-year span, and to relate these changes to those occurring in vertical skeletal facial relationships. Lateral cephalograms of 20 males and 15 females from the Iowa Facial Growth Study were evaluated at ages 5, 10, 15, 25, and 45 years. Correlation coefficients were computed to determine the relationship between overbite and various skeletal parameters. Analysis of variance and Duncan's multiple-range test were used to compare various periods of growth. Statistical significance was predetermined at the 0.05 level of confidence. No significant correlations were found between the absolute values of overbite and the vertical skeletal parameters in either males or females. Incremental changes in overbite during four growth periods were compared with changes in various vertical parameters and only a few significant correlations were found. In males, the change in overbite was significantly correlated with changes in N-Ans'/N-Me and MP:SN during the 10-to-15 year growth period. In females, the change in overbite was significantly correlated with changes in N-Ans'/N-Me% during the 5-to-10-year period and also with change in Ar'-Go/S-Go% during the 15-to-25-year period. In general, changes in overbite with age are difficult to predict from the initial overbite in the deciduous or mixed dentitions. On the other hand, evaluation of individual curves shows that males who initially had the least amount of overbite maintained that trend during the later stages of development. Although overbite changes were significantly associated with changes in some vertical parameters, the associations were not of clinical significance for predictive purposes, and overbite changes are probably dependent on concurrent changes in the growth of the alveolar processes.

Interest in using composite resin-glass ionomer hybrid cements as orthodontic bracket adhesives has grown because of their potential for fluoride release. The purpose of this pilot study was to compare shear bond strengths of three resin-glass ionomer cements (Advance, Fuji Duet, Fuji Ortho LC) used as bracket adhesives with a composite resin 24 hours and 30 days after bonding. The amount of adhesive remaining on the debonded enamel surface was scored for each adhesive. Mesh-backed stainless-steel brackets were bonded to 100 extracted human premolars, which were stored in artificial saliva at 37 degrees C until being tested to failure in a testing machine. The hybrid cements, with one exception, had bond strengths similar to those of the composite resin at 24 hours and 30 days. Fuji Ortho LC had significantly lower bond strengths (ANOVA p < or = 0.05) than the other adhesives at 24 hours and 30 days when it was bonded to unetched, water-moistened enamel. Adhesive-remnant scores were similar for all cements, except for cement Fuji Ortho LC when it was bonded to unetched enamel. The resin-glass ionomer cements we tested appear to have bond strengths suitable for routine use as orthodontic bracket-bonding adhesives.

The purpose of this study was to evaluate, on a longitudinal basis, changes in maxillary and mandibular arch length over a 45-year period. Subjects were drawn from two pools of normal individuals. Twenty-eight male and 33 female infants were evaluated longitudinally at 6 weeks, 1 year, and 2 years (before the eruption of the deciduous dentition). Fifteen males and 15 females from the Iowa Facial Growth Study were evaluated at 3, 5, 8, 13, 26, and 45 years. Arch length measurements were obtained independently by two investigators. Intra- and interexaminer reliabilities were predetermined at 0.25 and 0.5 mm, respectively. The greatest incremental increases occurred during the first two years of life. Arch length continued to increase until 13 years in the maxillary arch, and until 8 in the mandibular. Then significant and consistent decreases occurred in both arches mesial to the permanent first molars.

The purpose of this study was to assess the profile changes in subjects with Class II, Division 1 malocclusions who were treated either with or without the extraction of the four first premolars. The assessments were made by 39 lay persons. Profile silhouettes on 91 (44 extraction and 47 nonextraction) patients were evaluated at three stages: pretreatment, posttreatment, and approximately 2 years after treatment. Photographs matched for age and sex were also evaluated on 20 normal untreated subjects (10 males and 10 females). All rater assessments were analyzed statistically as to the effects of the following variables: (a) occlusion, i.e., normal or Class II, (b) treatment rendered, i.e., extraction or nonextraction, (c) gender, i.e., male or female, and (d) stage of observation, i.e., pretreatment, end of treatment or in retention. The current findings indicate that (1) before treatment, lay persons perceived the profile of normal patients more favorably than untreated patients with Class II, Division 1 malocclusions. (2) Immediately after treatment, raters perceived the changes in the profile of the extraction group more favorably than those in the nonextraction and normal groups. (3) At the end of the observation period (approximately 2 years posttreatment), raters did not evaluate the profile of any of the groups as being more favorable, but all groups were perceived more favorably than at the initial observation. (4) Raters perceived the profile changes with treatment more favorably in female subjects than in male subjects. In conclusion, orthodontic treatment seems to have a favorable effect on the profiles of both the extraction and nonextraction groups, both short- and long-term. Therefore, when based on proper diagnostic criteria, the posttreatment changes in the facial profile were perceived as favorable in both the extraction and nonextraction Class II, Division 1 groups when compared with the pretreatment profile.

Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p < or = 0.05. The results indicated that there was a significant difference in shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that enamel surface preparation using air-abrasion results in a significant lower bond strength and should not be advocated for routine clinical use as an enamel conditioner at this time.

It has been argued that the retention of some teeth in the jaws as overdenture abutments prevents negative feelings about the loss of natural teeth. This study set out to evaluate how satisfied a group of patients were with wearing overdentures, and to compare their subjective evaluations with those of a dentist using objective criteria to examine the prostheses. A questionnaire was developed using questions adapted from several other studies. It was pretested, modified and used on all patients who were members of a longitudinal study of overdentures that started in 1974, and who returned on recall. At the end of 9 months, 101 subjects had completed the questionnaire and examination. The mean age of the patients was 65.9 years with an age range of 35 to 88 years. There were 68 men and 33 women in this study and 62 of them were satisfied with their dentures; 33 were satisfied, but felt they had some faults. Only 6 were unhappy about wearing the overdentures. The average length of time the dentures had been worn was 6.9 years, with a range of 1 to 15 years. The most frequent complaints were loss of retention (65.4%) and discomfort (62.2%) of the mandibular dentures. A number of correlations were evaluated and some significant relationships were found between dentist and patient evaluation of the dentures. The best predictor of patient satisfaction with denture wearing was the patient's perception of retention and appearance. In the maxilla the patient's ability to chew and the dentist's evaluation of occlusion were also significant predictors. In the mandible the only other factors apart from retention and appearance were patient comfort and age.

Damage to the enamel surface during bonding and debonding of orthodontic brackets is a clinical concern. Alternative bonding methods that minimize enamel surface damage while maintaining a clinically useful bond strength is an aim of current research. The purpose of this study was to compare the effects on bond strength and bracket failure location of two adhesives (System 1+ and Scotchbond Multipurpose, 3M Dental Products Division) and two enamel conditioners (37% phosphoric acid and 10% maleic acid). Forty-eight freshly extracted human premolars were pumiced and divided into four groups of 12 teeth, and metal orthodontic brackets were attached to the enamel surface by one of four protocols: (1) System 1+ and phosphoric acid, (2) Scotchbond and phosphoric acid, (3) System 1+ and maleic acid, and (4) Scotchbond and maleic acid. After bracket attachment, the teeth were mounted in phenolic rings and stored in deionized water at 37 degrees C for 72 hours. A Zwick universal testing machine (Zwick GmbH & Co.) was used to determine shear bond strengths. The residual adhesive on the enamel surface was evaluated with the Adhesive Remnant Index. The analysis of variance was used to compare the four groups. Significance was predetermined at p < or = 0.05. The results indicated that there were no significant differences in bond strength among the four groups (p = 0.386). The results of the Chi square test, evaluating the residual adhesives on the enamel surfaces, revealed significant differences among the four groups (mean 2 = 0.005). A Duncan multiple range test revealed the difference occurred between the phosphoric acid and maleic acid groups, with maleic acid having bond failures at the enamel-adhesive interface. In conclusion, the use of Scotchbond Multipurpose and/or maleic acid does not significantly effect bond strength, however, the use of maleic acid resulted in an unfavorable bond failure location.

The purpose of this study was to evaluate on a longitudinal basis, the changes in intercanine and intermolar widths over a 45-year span. The subjects in this study were from two pools of normal persons: (1) 28 male and 33 female infants evaluated longitudinally at approximately 6 weeks, 1 year, and 2 years of age (before the complete eruption of the deciduous dentition); and (2) 15 male and 15 female subjects from the Iowa facial growth study evaluated at ages 3, 5, 8, 13, 26, and 45. Arch width measurements on maxillary and mandibular dental casts were obtained independently by two investigators. Intraexaminer and interexaminer reliability were predetermined at 0.5 mm. From the findings in the current study, the following conclusions can be made: (1) Between 6 weeks and 2 years of age, i.e., before the complete eruption of the deciduous dentition, there were significant increases in the maxillary and mandibular anterior and posterior arch widths in both male and female infants. (2) Intercanine and intermolar widths significantly increased between 3 and 13 years of age in both the maxillary and mandibular arches. After the complete eruption of the permanent dentition, there was a slight decrease in the dental arch widths, more in the intercanine than in the intermolar widths. (3) Mandibular intercanine width, on the average, was established by 8 years of age, i.e., after the eruption of the four incisors. After the eruption of the permanent dentition, the clinician should either expect no changes or a slight decrease in arch widths. In conclusion, although the dental arch widths undergo changes from birth until midadulthood, the magnitude as well as the direction of these changes do not provide a scientific basis for expanding the arches, in the average patient, beyond its established dimensions at the time of the complete eruption of the canines and molars. Both patients and clinicians should be aware of these limitations.