Compressive force strengthened the pro-inflammatory effect of zoledronic acid on il-1ß stimulated human periodontal fibroblasts.

OBJECTIVES: The number of patients in dentistry taking bisphosphonates (BP) increases every year. There are only little data about the influence of biomechanical stress due to orthodontic treatment and periodontal inflammation in BP patients. This study focused on the effects of the induced inflammation by IL-1ß in compressed human periodontal ligament fibroblasts (HPdLF) exposed to the nitrogen-containing BP zoledronate in vitro. MATERIALS AND METHODS: HPdLF were incubated with 5 µmol/l zoledronate and 10 ng/ml IL-1ß for 48 h. In the last 3 h, cells were exposed to a compressive, centrifugal force of 34.9 g/cm2. Cell viability was analyzed directly after the compressive force by MTT assay. Gene expression of COX-2 and IL-6 was investigated using quantitative qRT-PCR. PGE-2 and IL-6 protein secretion were measured via ELISA. RESULTS: The cell viability of HPdLF was not affected. Without inflammatory pre-stimulation, COX-2 expression was increased by compression and zoledronate. IL-6 expression was increased under compression. On secretion level, the combination of compression and zoledronate induced a slightly increase of IL-6 secretion. In contrast, inflammatory pre-stimulation strengthened the compressive upregulation of COX-2, as well as induced a higher PGE-2 secretion. Further addition of zoledronate to pre-stimulated cells additionally strengthened the compression-induced upregulation of COX-2 and IL-6 expression as well as protein secretion compared to all other groups. CONCLUSIONS: Biomechanical stress might trigger a pro-inflammatory potential of BP further enhanced in the presence of an inflammatory pre-stimulation. CLINICAL RELEVANCE: To prevent excessive host inflammatory responses, occlusal overloading and mechanical stress due to orthodontic treatment should be avoided in BP patients with untreated periodontitis.

Influence of clodronate and compressive force on IL-1ß-stimulated human periodontal ligament fibroblasts.

OBJECTIVES: The aim of this study was to investigate in vitro the effect of clodronate on interleukin-1ß (IL-1ß)-stimulated human periodontal ligament fibroblasts (HPdLFs) with the focus on inflammatory factors of orthodontic tooth movement with and without compressive force. MATERIALS AND METHODS: HPdLFs were incubated with 5 µM clodronate and 10 ng/mL IL-1ß. After 48 h, cells were exposed to 3 h of compressive force using a centrifuge. The gene expression of cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), matrix metalloproteinase 8 (MMP-8), and the tissue inhibitor of MMP (TIMP-1) was analyzed using RT-PCR. Prostaglandin E2 (PGE-2), IL-6, and TIMP-1 protein syntheses were quantified via ELISA. RESULTS: Compressive force and IL-1ß induced an overexpression of COX-2 gene expression (61.8-fold; p < 0.05 compared with control), diminished by clodronate (41.1-fold; p < 0.05 compared with control). Clodronate slowed down the compression and IL-1ß induced IL-6 gene expression (161-fold vs. 85.6-fold; p < 0.05 compared with control). TNF-α was only slightly affected without statistical significance. Clodronate reduced IL-1ß-stimulated MMP-8 expression with and without compressive force. TIMP-1 on gene and protein level was downregulated in all groups. Analyzing the MMP-8/TIMP-1 ratio, the highest ratio was detected in IL-1ß-stimulated HPdLFs with compressive force (21.2-fold; p < 0.05 compared with control). Clodronate diminished IL-1ß-induced upregulation of MMP-8/TIMP-1 ratio with (11.5-fold; p < 0.05 compared with control) and without (12.5-fold; p < 0.05 compared with control) compressive force. CONCLUSION: Our study demonstrates a slightly anti-inflammatory effect by clodronate under compressive force in vitro. Additionally, the periodontal remodeling presented by the MMP-8/TIMP-1 ratio seems to be diminished by clodronate. CLINICAL RELEVANCE: Reduction of pro-inflammatory factors and reduction of periodontal remodeling might explain reduced orthodontic tooth movement under clodronate intake.

Development of a novel histological and histomorphometric evaluation protocol for a standardized description of the mid-palatal suture - An ex vivo study.

The hard palate and mid-palatal suture are highly important for orthodontic treatment. In cases of transverse maxillary deficiency, palatal expansion is the treatment of choice. As nowadays a growing number of adult patients receive orthodontic treatment, an understanding of suture development throughout life is important to derive tailored orthodontic treatment techniques for each age group. Histological, histochemical and immunohistochemical stains (haematoxylin & eosin, Azan, Movat pentachrome, Masson-Goldner trichrome, Sirius Red, CD 31, osteopontin and TRAP) and histomorphometric analyses were re-established to detect the structural conditions of the mid-palatal suture in human cadavers of three different age groups (20-39, 40-59 and 60-80 years). The mid-palatal suture of the selected age groups (total of n = 12; n = 4 in every group m = f) exhibited marked differences in sutural morphology and metabolism. A wide, interdigitated and well-vascularized suture was observed in younger specimens compared with straighter and smaller sutures with fewer vessels and lower bone density in the 60-80 year group. The fibre composition within the sutural gap differed between the three age groups. Delicate fibres were found in the 20-39 year group, and a tightly interwoven 3D fibre-network was observed in the 40-59 year group. Atrophy primarily characterized the fibres in the 60-80 year group. This evidence demonstrates differences between the evaluated groups. These results suggest that the staining methods used are suitable for the description and evaluation of the morphology and metabolism of mid-palatal sutures. Further investigation is necessary to provide an in-depth description of sutural maturation over a lifetime.

Plaque levels of patients with fixed orthodontic appliances measured by digital plaque image analysis.

INTRODUCTION: A digital plaque image analysis system was developed to objectively assess dental plaque formation and coverage in patients treated with fixed orthodontic appliances. METHODS: The technique was used to assess plaque levels of 52 patients undergoing treatment with fixed appliances in the Department of Orthodontics at Johannes Gutenberg University in Mainz, Germany. RESULTS: Plaque levels ranged from 5.1% to 85.3% of the analyzed tooth areas. About 37% of the patients had plaque levels over 50% of the dentition, but only 10% exhibited plaque levels below 15% of tooth coverage. The mean plaque coverage was 41.9% ± 18.8%. Plaque was mostly present along the gum line and around the orthodontic brackets and wires. CONCLUSIONS: The digital plaque image analysis system might provide a convenient quantitative technique to assess oral hygiene in orthodontic patients with multi-bracket appliances. Plaque coverage in orthodontic patients is extremely high and is 2 to 3 times higher than levels observed in high plaque-forming adults without appliances participating in clinical studies of the digital plaque image analysis system. Improved hygiene, chemotherapeutic regimens, and compliance are necessary in these patients.

Clinical observations and success rates of palatal implants.

INTRODUCTION: Anchorage control is a challenge in orthodontics. Implants can be used to provide absolute anchorage.The aim of this study was to evaluate the success rates of palatal implants used for various anchorage purposes. METHODS: Thirty-four palatal implants were placed in 33 patients. In the adults (n = 9), the implants (n = 9) were placed in the median palatal suture. In the adolescents (n = 24), the implants (n = 25) were placed in the paramedian region. The implants were used to support a transpalatal arch, a modified distal jet appliance, or a modified hyrax screw. An implant was considered successful if it could be used as planned throughout the orthodontic treatment. The patients were asked to evaluate their pain perception after placement and explantation procedures. RESULTS: Three implants failed early (during the waiting period before orthodontic loading, within 3 months after placement). During the orthodontic loading period, no implants were lost. No statistically significant correlations were found between success rate and sex, age, primary stability, placement site (median or paramedian), implant size, or palatal depth. Pain perception after surgery was acceptable. The success rate of the palatal implants in this study was 91%. CONCLUSIONS: Palatal implants are a reliable method of providing absolute anchorage control in a variety of patients for different indications. They can be loaded both directly and indirectly.

Perception of esthetic orthodontic appliances: An eye tracking and cross-sectional study.

OBJECTIVE: To evaluate the perception of esthetic orthodontic appliances by means of eye-tracking measurements and survey investigation. MATERIALS AND METHODS: En face and close-up images with different orthodontic appliances (aligner appliance [a], aligner appliance and attachments [b], lingual appliance [c], ceramic brackets [d], no appliance [e; control]) were shown to 140 participants. Eye movement and gaze direction was recorded by eye-tracking system. For different anatomical areas and areas of the appliances, time to first fixation and total fixation time were recorded. The questions included in a visual analog scale regarding individual sentiency were answered by the participants. RESULTS: For all groups, the anatomical landmarks were inspected in the following order: (1) eyes, (2) mouth, (3) nose, (4) hair, and (5) ears. Only in group d, first fixation was on the mouth region (1.10 ± 1.05 seconds). All appliances except the lingual appliance (1.87 ± 1.31 seconds) resulted in a longer fixation on the mouth area (a, 2.97 ± 1.32 seconds; b, 3.35 ± 1.38 seconds; d, 3.29 ± 1.36 seconds). For close-up pictures, the fastest (0.58 seconds) and longest (3.14 seconds) fixation was found for group d, followed by group b (1.02 seconds/2.3 seconds), group a (2.57 seconds/0.83 seconds), and group c (3.28 seconds/0.05 seconds). Visual analog scale scoring of questions on visibility were consistent with eye-tracking measurements. With increasing visibility, the feeling of esthetic impairment was considered higher. CONCLUSIONS: Lingual orthodontic appliances do not change how the face is perceived. Other esthetic orthodontic appliances may change the pattern of facial inspection and are different in subjective perception.

Incorrect measurements and misleading conclusions in the article "Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study".

BACKGROUND/OBJECTIVE: To reproduce the methods and results of the study by Alobeid et al. (2018) in which the efficacy of tooth alignment using conventional labial and lingual orthodontic bracket systems was assessed. MATERIALS/METHODS: We used the identical experimental protocol and tested (i) regular twin bracket (GAC-Twin [Dentsply]) and lingual twin bracket systems (Incognito [3M]), (ii) together with NiTi 0.014" wires (RMO), and (iii) a simulated malocclusion with a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). RESULTS: The method described by Alobeid et al. (2018) is not reproducible, and cannot be used to assess the efficacy of tooth alignment in labial or lingual orthodontic treatment. Major flaws concern the anteroposterior return of the Thermaloy-NiTi wire ligated with stainless steel ligatures. The reproduced experimental setting showed that a deflected Thermaloy-NiTi wire DOES NOT move back at all to its initial stage (= 0 per cent correction) because of friction and binding (see supplemented video), neither with the tested labial nor with the lingual brackets. Furthermore, an overcorrection of up to 138 per cent, which the authors indicate for some labial bracket-wire combinations and which deserves the characterization "irreal", stresses the inappropriateness of the method of measurement.Further flaws include: a) incorrect interpretation of the measurement results, where a tooth tripping around (overcorrection) is interpreted as a better outcome than a perfect 100 per cent correction; b) using a statistical test in an inappropriate and misleading way; c) uncritical copying of text passages from older publications to describe the method, which do not correspond to this experimental protocol and lead to calculation errors; d) wrong citations; e)differences in table and bar graph values of the same variable; f) using a lingual mushroom shaped 0.013" Thermaloy-NiTi wire which does not exist; g) drawing uncritical conclusions of so called "clinical relevance" from a very limited in vitro testing. CONCLUSIONS: Clinical recommendations based on in vitro measurements using the Orthodontic Measurement and Simulation System (OMSS) should be read with caution.

Palatal implants in adolescents: a histological evaluation in beagle dogs.

OBJECTIVES: Small osseointegrated implants inserted in the palate provide a reliable anchorage control during orthodontic treatment. When these implants are inserted in the median palatal suture in adolescents, there might be interference with normal transverse development of the maxilla. The aim of this study was to determine histometrically the influence of implants inserted in the median palatal suture in adolescent beagle dogs on transverse maxillary development and to determine the amount of osseointegration of unloaded palatal implants in the median palatal suture in adolescent beagle dogs. MATERIAL AND METHODS: Two palatal implants were inserted in the median palatal suture in four of five adolescent beagle dogs. The experimental period took 25 weeks, and the dogs were subjected to a scheme of sequential point labelling with vital stains every 6 weeks. Insertion sites were examined microscopically and histometric analysis was performed. RESULTS AND DISCUSSION: Both anterior width and posterior width were wider in the control dog as compared with the average in the test dogs, 3.7% and 9.5%, respectively. After loss of a palatal implant, immediate repair of the bone in the suture area could be observed. In the posterior region, the repaired suture looked more like a suture in the infantile stage in humans, instead of having a sinusoidal course, as was observed in the control dog and in adolescent humans. The amount of osseointegration varied from 43% to 64.3%. CONCLUSION: The results of this study support the idea that in adolescents, palatal implants should not be inserted in the median palatal suture because of possible growth impairment (transverse maxillary development). The amount of osseointegration of unloaded palatal implants in the median palatal suture in adolescent dogs is less as compared with dental implants in dogs and loaded palatal implants in adult humans.

The effect of debonding and/or bleaching on enamel color - an in-vitro study.

AIM: There are various studies in the literature on bonding brackets to bleached teeth and on the effect of bleaching material on the color of compomers. The purpose of this study was to investigate changes in tooth color depending on the process of bonding - debonding and/or bleaching. MATERIAL AND METHODS: Ninety crowns of lower bovine permanent incisors were divided into nine subgroups. Three bonding materials (chemical, light- and pressure-cured) and three bleaching materials (15% CP, 35% CP, or 38% HP) were applied to the teeth, whereby each tooth was divided into quarters: untreated, bleached only, bonded-debonded only, and bleached after a bonding-debonding procedure. The Easyshade spectrophotometer was used to determine CIELCh coordinates (lightness, color, and hue) three times for each area. The areas' differences in color were expressed as the Euclidian distance DeltaE. Four examiners (two orthodontists and two dentists) rated each tooth concerning color differences in the four areas. The data collected was subjected to the sign and Wilcoxon or the Kruskal-Wallis and Mann-Whitney U tests using the SPSS 12.0 program. RESULTS: Examiners found significant differences between those areas with and those without bleaching within each group of specimens (p < 0.05), but there were no differences concerning the bonding and debonding procedures (p > 0.05). Furthermore, digital tooth-shade measurements revealed no statistically-significant group-associated differences between those areas treated with bonding material and those not so treated, nor between bonded and debonded areas (p > 0.05). Nor did we observe any statistically-significant differences between bleached areas and those areas bleached after bonding and debonding procedures (p > 0.05). CONCLUSION: The processes of bonding and debonding alone do not seem to have any statistically-significant influence on the tooth color of bovine enamel using these testing materials, nor does the subsequent bleaching procedure.

Miniscrews or palatal implants for skeletal anchorage in the maxilla: comparative aspects for decision making.

The advantages and disadvantages associated with placement, orthodontic treatment, and removal of miniscrews and palatal implants should be clearly understood by both the orthodontist and the patient. Device design, preoperative diagnostic measures, insertion and removal procedures, potential suprastructure application, implant migration and success rate, biomechanical anchorage facilities, and comparative risks and complications of both miniscrews and palatal implants must be considered if skeletal anchorage is intended to be used in the maxilla. This article reviews these and other factors to help clinicians decide which device should be selected for each individual case.

Skeletal anchorage in orthodontics--basics and clinical application.

This review article describes the basics and clinical applications of skeletal anchorage in orthodontics, namely: areas of indication, anchorage devices, insertion areas, indications, potential complications, and their use in growing patients. The areas for skeletal anchorage include orthodontic-prosthetic anchorage, orthodontic anchorage, and skeletal anchorage in orthopedic therapy procedures. The anchorage devices currently available are: prosthetic implants, mini screws, palatal implants, onplants, bone anchors, zygoma wires and skeletally-supported distractors. The insertion areas described so far (according to therapeutic procedure and bone supply available) include edentulous jaw sections, the interdental septum, infra-apical and supra-apical areas, the palate (median, paramedian, lateral), the retromolar area, and the zygomatic bone. Force systems are applied (direct or indirect anchorage) according to surgical and orthodontic or orthopedic requirements. Skeletal anchorage devices should be selected according to the following criteria. Is the anchorage task unifunctional or multifunctional? How many anchorage devices are required for the therapy in question? What is the success rate of the various anchorage devices; what are the applicable biomechanics and soft tissue or hard tissue conditions in the insertion area? The success rates for miniscrews are currently between 80% and 90%, and over 90% for palatal implants. The potential of skeletal anchorage is broadening the current orthodontic treatment spectrum, guaranteeing the practitioner absolute control of anchorage by avoiding the unpredictable reactions of periodontal anchorage, leading to a reduction in unwanted side effects.

The discoloring effects of food on the color stability of esthetic brackets--an in-vitro study.

AIM: The purpose of this study was to investigate the discoloring effect of certain foods on the color stability of esthetic brackets made of different materials. MATERIAL AND METHODS: Ten specimens of six different tooth-colored brackets were immersed for 10 days at 37 degrees C in various solutions (de-ionized water, tea, coffee, red wine, orange juice, curry and cress) or exposed to accelerated photo-aging (150 KJ/ m(2), 340 nm). Using the Easyshade device, the brackets were analyzed at the beginning of the experiment and after ultrasound-cleaning daily thereafter for ten days according to CIELCh coordinates lightness, chroma and hue. Our results were evaluated using the SPSS-12.0 statistical program and subjected to the Kruskal-Wallis and/or Mann-Whitney U tests. RESULTS: The results can be divided into three types of reactions. The brackets exposed to UV light, cress or orange juice showed no visible discoloration. The measured color differences remained in the same range as the measurements for brackets in the control group. All brackets immersed in red wine, tea or coffee showed similar reactions, with a sharp increase in discoloration after 5 days (corresponding to high consumption). In the curry solution, the brackets made of polyoxymethylene became immediately discolored; all other bracket types showed no visible reaction. CONCLUSIONS: This in-vitro test can only simulate the actual intra-oral situation, but the results seem to demonstrate that the consumption of certain foods greatly influences to what extent the color of tooth-colored brackets changes.

Single tooth torque correction in the lower frontal area by a completely customized lingual appliance.

BACKGROUND: Aim of this study was to analyze the efficacy and precision of the completely customized lingual appliance (CCLA) regarding the single tooth torque correction. The study also examined external apical root resorptions as possible side effects of torque correction and the changings of the periodontal situation. METHODS: A case series of three patients were included. The patients showed a single tooth torque problem with a gingival recession and were treated with the CCLA. Plaster casts before and after treatment and plaster casts of the set up were scanned and superimposed. Deviations between the two plaster casts were analyzed at different points of interest. Changes of the gingival recession were compared before and after treatment. Relative root resorptions were measured by the orthopantomograms. Treatment times were assessed by the records of the patients. Results were presented descriptively. RESULTS: The mean change of the most apical part of the root reached by the orthodontic treatment was 1.8 ± 0.3 mm. The largest deviation between set up and final model was measured on the occlusal surface of the tooth 36 with 0.8 mm. Most measurement points showed a deviation of 0.5 mm or less. The depths of the gingival recession showed a significant reduction of 4.7 mm. The widths of the gingival recession were reduced by 1.1 mm. The average relative root resorption of the corrected teeth was 2.7 ± 1.5%. The average treatment time was 13.8 ± 4.5 months. CONCLUSIONS: This is the first study showing that the CCLA with its high precision is very effective in correcting single tooth torque problems. Orthodontic torque correction resulted in a significant reduction of gingival recessions and caused only negligible root resorptions.

The unilateral chewing phenomenon, occlusion, and TMD.

The aim of this study was to evaluate the role of occlusal factors to determine the extent of their role in temporomandibular disorders (TMD). Two groups were selected: a patient group (I) of 100 patients with TMD problems (pain and clicking) and a control group (II) of 100. Each individual had to have 28 permanent teeth. A clinical evaluation was conducted and the models were evaluated according to the criteria of the Angle Classes and the Reinhardt Index, with the number of permanent teeth (A), the number of the correctly (R) and the number of incorrectly (F) related antagonist pairs of teeth. The individuals had to observe the preference of their chewing side. The results of this investigation revealed: the number of F can be used as an occlusal indicator for possible functional disorders (p=0.041). Individuals with one chewing side have more signs and symptoms of TMD (p<6.22x10(-9)).

Molar distalization with a modified pendulum appliance--in vitro analysis of the force systems and in vivo study in children and adolescents.

The standard pendulum appliance was modified by integrating a distal screw into its base and by special preactivation of the pendulum springs. The suitability of this Pendulum K for the translatory distalization of maxillary molars was investigated in an in vitro analysis and in an in vivo study in children and adolescents. The in vitro measurement of the resulting force systems revealed that all forces and moments remained virtually constant over a three-mm simulated distalization increment. The transverse force, Fx, increased from two to 11 cN and the weakly intrusively acting force, Fy, from six to eight cN, but these increases were not statistically significant. The distalization force, Fz, initially 201 cN, was still 199 cN after a three-mm distalization increment. The mesially acting moment, My, rose from 1654 to 1834 cN mm, whereas the palatally acting moment, Mz, declined slightly from 229 to 164 cN mm. The slight, consistent distoinclinatory moment, Mx, initially 306 cN mm, was 310 cN mm after three mm. In parallel, the in vivo study with its collective of 66 patients confirmed that the Pendulum K allows a virtually translatory molar distalization with slight tippings of 4.75 degrees to the palatal plane and 4.25 degrees to the anterior basal plane. Palatal movements of the first molars were avoided. The proportion of molar distalization in the total movement was 73.53%.

Orthodontic anchorage implants inserted in the median palatal suture and normal transverse maxillary growth in growing dogs: a biometric and radiographic study.

Small osseointegrated implants inserted in the palate provide a reliable anchorage control during orthodontic treatment. When these implants are inserted in the median palatal suture in growing individuals, the possible effects on normal transverse maxillary growth are still unknown. Therefore, the aim of this study was to evaluate the influence of orthodontic anchorage implants on transverse maxillary growth when inserted in the median palatal suture of growing dogs. Five growing dogs were used, one of them randomly selected as a control dog. The test dogs each received two implants in the median palatal suture. Impressions and occlusal radiographs of the upper jaws were taken at baseline (TO), after 84 days (T1), and at the end of the study after 168 days (T2). Measurements to compare increases in maxillary width between test dogs and control dog were performed on study casts and occlusal radiographs at TO, T1, and T2. Restricted transverse growth was observed in the test dogs in the canine region. Transverse growth in the region of second and fourth premolars was similar for the test dogs and the control dog. These results may be of some clinical relevance when orthodontic anchorage implants are to be inserted in growing individuals. An alternative insertion site, for example the parasagittal region, should be considered in these cases, to avoid possible negative effects on normal transverse maxillary development.

Age-related changes in the midpalatal suture. A histomorphometric study.

AIM: The issue of the present study was to register age-related morphological differences with reference to the mean sutural width (MSW) and the degree of obliteration (O) in the region of the human midpalatal suture. MATERIAL AND METHODS: 22 human palate specimens from subjects of different ages (18-63 years) were available for this purpose. Three sections (anterior, median and posterior) from each specimen underwent histological preparation and staining with toluidine blue before being subjected to histological and histomorphometric analysis. Two age groups (< or = 25 years and > or = 26 years) were formed. RESULTS: The findings showed that the median sutural width in the younger group (< or = 25 years) was 211.20 microm versus only 161.16 microm in the older group. This difference was statistically significant (p = 0.05). The proportion of ossified tissue in the entire suture (obliteration) was low in all subjects. At 13.10%, the maximum obliteration measured was found in a 44-year-old man in the older age group. The median value of the ossification was 0% in the younger age group and 3.11% in the group > or = 26 years. This difference was statistically significant (p = 0.036). The earliest ossification was registered in a 21-year-old man. The oldest subject without ossification was a 54-year-old man. In terms of local topography, no statistically significant differences between anterior, median and posterior palatal region were observed with respect to the two investigated parameters (MSW, O). CONCLUSION: These findings confirm that ossification of the midpalatal suture is not a valid reason for the increased transversal resistance encountered during rapid palatal expansion in younger subjects (< or = 25 years) as well as in many older persons.

Load-deflection behavior of transpalatal bars supported on orthodontic palatal implants. An in vitro study.

Within the scope of indirect orthodontic implant anchorage, the transpalatal bar (TPB) transmits the forces applied at the anchorage teeth to an implant inserted into the palate. It is thus the connecting element between teeth and palatal implant. The aim of the present study was to analyze the extent of sagittal deflection of TPBs of different dimensions attached to an implant abutment. For this purpose, commercially available stainless steel wires measuring 1.2 mm x 1.2 mm (n = 25) and 0.8 mm x 0.8 mm (n = 25) respectively were bent to comply with a representative bend specified with respect to casts, fixed with clamp caps to the implant abutment, and exposed for forces of 50, 100, 150, 200 and 300 cN. The mean deflection of the 1.2 mm x 1.2 mm TPB was lower by a factor of 4.5 than that of the 0.8 mm x 0.8 mm TPB. With a clinically relevant load of 200 cN, for example, the mean deflection of the 1.2 mm x 1.2 mm (0.051" x 0.051") TPB was 301 microm, whereas that of the 0.8 mm x 0.8 mm (0.032" x 0.032") TPB was 1337 microm. When maximum anchorage is required, 1.2 mm x 1.2 mm (0.051" x 0.051") TPBs should be used as a matter of principle.

Osteogenic differentiation of periodontal fibroblasts is dependent on the strength of mechanical strain.

OBJECTIVE: During orthodontic therapy the correct strength of mechanical strain plays a key role for bone remodelling during tooth movement. Aim of this study was to investigate the osteogenic differentiation of human periodontal ligament fibroblasts (HPdLF) depending on the applied strength of mechanical strain compared to osteoblasts (HOB). DESIGN: HPdLF and HOB were loaded with different strengths (1%, 5% and 10%) of static mechanical strain (SMS) for 12h in vitro. Viability was verified by MTT and apoptosis by TUNEL assay. Gene expression of cyclin D1, collagen type-1 (COL-I), alkaline phosphatase (ALP), osteocalcin, osteoprotegerin (OPG) and receptor activator of the NF-κB ligand (RANKL) were investigated using RT-PCR. OPG and RANKL synthesis was measured by ELISA and ALP activity by colorimetric assay. RESULTS: 10% of SMS led to a decrease in cell viability of both cells lines, but no increased rate of apoptosis. RT-PCR showed the highest increase of cyclin D1 expression for HPdLF and HOB when applied to 5% of SMS, and HOB showed a doubling of COL-I gene expression. HPdLF and HOB showed a strength-dependent synthesis of OPG and ALP activity, whereas HOB demonstrated a decrease in OPG synthesis and ALP activity when applied to 10% of SMS. CONCLUSION: Osteogenic differentiation of HPdLF correlates with increasing strength of SMS. HOB show decreased activity when applied to high SMS, demonstrating potential damage to the bone remodelling due to strain of high strength. SMS up to 5% provides the best conditions for bone formation at the tension site of tooth movement.

Influence of patient age and experience of the surgeon on early complications after surgical closure of the cleft palate--a retrospective cohort study.

Comparative studies on timing of palatoplasty are rare. The aim of this retrospective cohort study was to compare the influence of early (<14 months) and later (>14 months) one-step closure of the soft and hard palate on early complications. All non-syndromic patients from 1999 to 2009 were included; 6-14 months n = 41 and 15-24 months n = 53. Each palatoplasty was performed as a single-step procedure using bipedicled flaps by a team of two Maxillofacial Surgeons either supervising or operating. The surgeon was rated as "non-experienced" when having performed less than 10 palatoplasties under supervision. Main outcome variable is the occurrence of residual fistula. Fistula occurred in four (4.5%) of the patients. In the multivariate model with respect to the occurrence of fistula neither age, leucocyte count, duration of surgery, nor experience of the surgeon showed a significant influence on the occurrence of a fistula. Only reduced weight contributed to a significantly higher risk of post-operative fistula. In conclusion patient age, experience of surgeon, and duration of surgery had no influence on the early outcome. High leucocyte count had a tendency for and reduced weight had a significant influence on fistula occurrence. Long-term outcome on speech development and maxillary growth have to be collected.