Effect of voxel size in cone-beam computed tomography on surface area measurements of dehiscences and fenestrations in the lower anterior buccal region.

OBJECTIVES: This study aims to assess whether different voxel sizes in cone-beam computed tomography (CBCT) affected surface area measurements of dehiscences and fenestrations in the mandibular anterior buccal region. MATERIALS AND METHODS: Nineteen dry human mandibles were scanned with a surface scanner (SS). Wax was attached to the mandibles as a soft tissue equivalent. Three-dimensional digital models were generated with a CBCT unit, with voxel sizes of 0.200 mm (VS200), 0.400 mm (VS400), and 0.600 mm (VS600). The buccal surface areas of the six anterior teeth were measured (in mm2) to evaluate areas of dehiscences and fenestrations. Differences between the CBCT and SS measurements were determined in a linear mixed model analysis. RESULTS: The mean surface area per tooth was 88.3 ± 24.0 mm2, with the SS, and 94.6 ± 26.5 (VS200), 95.1 ± 27.3 (VS400), and 96.0 ± 26.5 (VS600), with CBCT scans. Larger surface areas resulted in larger differences between CBCT and SS measurements (- 0.1 ß, SE = 0.02, p < 0.001). Deviations from SS measurements were larger with VS600, compared to VS200 (1.3 ß, SE = 0.05, P = 0.009). Fenestrations were undetectable with CBCT. CONCLUSIONS: CBCT imaging magnified the surface area of dehiscences in the anterior buccal region of the mandible by 7 to 9%. The larger the voxel size, the larger the deviation from SS measurements. Fenestrations were not detectable with CBCT. CLINICAL RELEVANCE: CBCT is an acceptable tool for measuring dehiscences but not fenestrations. However, CBCT overestimates the size of dehiscences, and the degree of overestimation depends on the actual dehiscence size and CBCT voxel size employed.

Precision of orthodontic cephalometric measurements on ultra low dose-low dose CBCT reconstructed cephalograms.

OBJECTIVES: To analyze differences in variation of orthodontic diagnostic measurements on lateral cephalograms reconstructed from ultra low dose-low dose (ULD-LD) cone beam computed tomography (CBCT) scans (RLC) as compared to variation of measurements on standard lateral cephalograms (SLC), and to determine if it is justifiable to replace a traditional orthodontic image set for an ULD-LD CBCT with a reconstructed lateral cephalogram. MATERIAL AND METHODS: ULD-LD CBCT images and SLCs were made of forty-three dry human skulls. From the ULD-LD CBCT dataset, a lateral cephalogram was reconstructed (RLC). Cephalometric landmarks (13 skeletal and 7 dental) were identified on both SLC and RLC twice in two sessions by two calibrated observers. Thirteen cephalometric variables were calculated. Variations of measurements, expressed as standard deviations of the 4 measurements on SLC and RLC, were analyzed using a paired sample t-test. Differences in the number of observations deviating ≥ 2.0 mm or degrees from the grand mean between SLC and RLC were analyzed using a McNemar test. RESULTS: Mean SDs for 7 out of 13 variables were significantly smaller for SLCs than those for RLCs, but differences were small. For 9 out of 13 variables, there was no significant difference between SLC and RLC for the number of measurements outside the range of 2 mm or degrees. CONCLUSIONS: Based on the lower radiation dose and the small differences in variation in cephalometric measurements on reconstructed LC compared to standard dose LC, ULD-LD CBCT with reconstructed LC should be considered for orthodontic diagnostic purposes. CLINICAL RELEVANCE: ULD-LD CBCT with reconstructed LC should be considered for orthodontic purposes.

Symmetry of palatal shape during the first year of life in healthy infants.

OBJECTIVES: The purpose of this study was to quantify the symmetry of the alveolar process of the maxilla and palate during the first year of life in healthy infants with the help of a semiautomatic segmentation technique. MATERIALS AND METHODS: Maxillary plaster models of seventy healthy babies at 0, 3, 6, 9, and 12 months were collected and digitized. A semiautomatic segmentation tool was used to extract the alveolus and palate. The resulting model was aligned within a reference frame and mirrored on its medial plane. Distance maps were created and analyzed to compare and quantify the differences between the two hemispheres. Additional hemispherical width and area measurements were performed. An ANOVA test with additional post hoc tests was performed to check if the symmetry changed during development. Finally, the results were tested on intra- and interobserver variability. RESULTS: The absolute mean inter-surface distance between the original and mirrored models in each age group ranged between 0.23 and 0.30 mm. Width and area analysis showed a small but significant larger left palatal hemisphere. ANOVA and post hoc tests showed no significant difference in symmetry between groups. Reliability analysis showed no significant differences between observers. CONCLUSIONS: This study showed that in this infant population, only a small degree of palatal asymmetry was present, which can be considered as normal and clinically irrelevant. CLINICAL RELEVANCE: The data from this study can be used in future comparative studies as reference data. Furthermore, modeling of these data can help in predicting the growth pattern, which may lead to improved treatment protocols for children with craniofacial anomalies.

[Root resorption as a result of orthodontic treatment]. / Wortelresorptie als gevolg van orthodontische behandeling.

Apical root resorption is a biological process induced when orthodontic force is exerted on a tooth and local necrosis of the periodontal ligament occurs. Macrophages remove the necrotic tissue. In this way, differentiating osteoclasts can both attach to the now available dental surface and can then provoke root resorption. There is considerable uncertainty among dental practitioners on how to deal with clinically relevant apical root resorption (bigger/equal 2 mm) during or after orthodontic treatment. To increase understanding and to improve the quality of care, the Dutch Association of Orthodontists has developed a clinical practice guideline. Recommendations have been formulated for the diagnosis of apical root resorption, possible risk factors and treatment management in order to respond adequately to this problem in practice.

Three dimensional maxillary growth modeling in newborns.

OBJECTIVES: The aim of this study was to develop an accurate and intuitive semi-automatic segmentation technique to calculate an average maxillary arch and palatal growth profile for healthy newborns in their first year of life. MATERIALS AND METHODS: Seventy babies born between 1985 and 1988 were included in this study. Each child had five impressions made in the first year after birth that were digitalized. A semi-automatic segmentation tool was developed and used to assess the maxillary dimensions. Finally, random effect models were built to describe the growth and build a simulation population of 10,000 newborns. The segmentation was tested for inter- and intra-observer variability. RESULTS: The Pearson correlation coefficient for each of the variables was between 0.94 and 1.00, indicating high inter-observer agreement. The paired sample t test showed that, except for the tuberosity distance, there were small, but significant differences in the landmark placements between observers. Intra-observer repeatability was high, with Pearson correlation coefficients ranging from 0.87 to 1.00 for all measurements, and the mean differences were not significant. A third or second degree growth curve could be successfully made for each parameter. CONCLUSIONS: These findings indicated this method could be used for objective clinical evaluation of maxillary growth. CLINICAL RELEVANCE: The resulting growth models can be used for growth studies in healthy newborns and for growth and treatment outcome studies in children with cleft lip and palate or other craniofacial anomalies.

Orthodontics with Customized versus Noncustomized Appliances: A Randomized Controlled Clinical Trial.

This randomized controlled trial aimed to evaluate the duration and outcome quality of orthodontic treatment with a customized fixed appliance system versus a noncustomized system. Patients ( n = 180) were randomized and received orthodontic treatment with the Insignia customized orthodontic system or the Damon Q noncustomized orthodontic system. The allocation sequence was concealed using identical, sequentially numbered, opaque, sealed envelopes. Patients with nonextraction treatment plans were treated by 2 equally experienced orthodontists. Pretreatment and posttreatment plaster casts were made for each patient, and the models were rated using the Peer Assessment Rating (PAR) score. Planning time, treatment duration, and numbers of loose brackets, visits, and complaints were recorded. The examined null hypothesis was that the customized appliance system was not associated with significantly ( P < 0.05) shorter treatment duration compared to a noncustomized appliance. We analyzed 85 patients in the customized group and 89 in the noncustomized group. Treatment duration was 1.29 ± 0.35 y in the customized group and 1.24 ± 0.37 y in the noncustomized group. In the customized group, the PAR score was 23.32 ± 9.15 pretreatment and 5.38 ± 3.75 posttreatment. In the noncustomized group, the PAR score was 21.84 ± 7.95 pretreatment and 5.93 ± 3.58 posttreatment. None of these outcomes significantly differed between groups. On the other hand, the orthodontist had a significant effect on treatment duration, quality of treatment outcome, and number of visits ( P < 0.05). A higher PAR score pretreatment was associated with increased treatment duration, posttreatment PAR, and number of visits ( P < 0.05). Compared to the noncustomized group, the customized group had more loose brackets, a longer planning time, and more complaints ( P < 0.05). The customized orthodontic system was not associated with significantly reduced treatment duration, and treatment quality was comparable between the 2 systems ( ClinicalTrials.gov : NCT01268852).

Neonatal Satellite Cells Form Small Myotubes In Vitro.

Although palatal muscle reconstruction in patients with cleft palate takes place during early childhood, normal speech development is often not achieved. We hypothesized that the intrinsic properties of head satellite cells (SCs) and the young age of these patients contribute to the poor muscle regeneration after surgery. First, we studied the fiber type distribution and the expression of SC markers in ex vivo muscle tissue from head (branchiomeric) and limb (somite-derived) muscles from neonatal (2-wk-old) and young (9-wk-old) rats. Next, we cultured SCs isolated from these muscles for 5, 7, and 9 d, and investigated the in vitro expression of SC markers, as well as changes in proliferation, early differentiation, and fusion index (myotube formation) in these cells. In our ex vivo samples, we found that virtually all myofibers in both the masseter (Mass) and the levator veli palatini (LVP) muscles contained fast myosin heavy chain (MyHC), and a small percentage of digastric (Dig) and extensor digitorum longus myofibers also contained slow MyHC. This was independent of age. More SCs were found in muscles from neonatal rats as compared with young rats [17.6 (3.8%) v. 2.3 (1.6%); P < 0.0001]. In vitro, young branchiomeric head muscle (BrHM) SCs proliferated longer and differentiated later than limb muscle SCs. No differences were found between SC cultures from the different BrHMs. SC cultures from neonatal muscles showed a much higher proliferation index than those from young animals at 5 d (0.8 v. 0.2; P < 0.001). In contrast, the fusion index in neonate SCs was about twice as low as that in SCs from young muscles at 9 d [27.6 (1.4) v. 62.8 (10.2), P < 0.0001]. In conclusion, SCs from BrHM differ from limb muscles especially in their delayed differentiation. SCs from neonatal muscles form myotubes less efficiently than those from young muscles. These age-dependent differences in stem cell properties urge careful consideration for future clinical applications in patients with cleft palate.

Use of a modified Furlow Z-plasty as a secondary cleft palate repair procedure to reduce velopharyngeal insufficiency.

Cleft palate repair is done to allow for normal speech by separating the oral and nasal cavities and creating a functioning velopharyngeal valve. However, despite cleft palate repair, some patients demonstrate velopharyngeal insufficiency (VPI). An attempt was made to determine the effectiveness of a modified secondary Furlow Z-plasty in improving VPI. Fifty-five children aged between 12 and 15 years, with postoperative VPI following primary palatoplasty, were included in the study. These children underwent a modified Furlow Z-plasty. Nasometry was done to determine the change in velopharyngeal function due to the secondary Furlow Z-plasty by comparing the preoperative with the 1-year postoperative nasalance scores. A test-retest study was performed to determine the reliability of the nasometric measures. Reliability measurements of the nasometer passages revealed good reliability for 18 out of the 25 speech passages. There was a statistically significant reduction in VPI at 1 year postoperative in patients who were treated with the modified Furlow Z-plasty, with a P-value of <0.001 in all passages, except velar plosives, which had a P-value of 0.002. Patients with VPI after primary palatoplasty and treated using a modified Furlow Z-plasty had significantly lower nasalance scores at 1 year postoperative, indicating significantly improved velopharyngeal function.

Caries preventive measures in orthodontic practice: the development of a clinical practice guideline.

OBJECTIVES: White spot lesions (WSLs) are a side effect of orthodontic treatment, causing esthetic problems and a risk of deeper enamel and dentine lesions. Many strategies have been developed for preventing WSLs, but great variability exists in preventive measures between orthodontists. This study developed statements on which a clinical practice guideline (CPG) can be developed in order to help orthodontists select preventive measures based on the best available evidence. MATERIALS AND METHODS: A nominal group technique (RAND-e modified Delphi procedure) was used. A multidisciplinary expert panel rated 264 practice- and evidence-based statements related to the management of WSLs. To provide panel members with the same knowledge, a total of six articles obtained from a systematic review of the literature were read by the panel in preparation of three consensus rounds. According to the technique, a threshold of 75% of all ratings within any 3-point section of the 9-point scale regarding a specific statement was accepted as consensus. RESULTS: After the first and second consensus rounds, consensus was reached on 37.5 and 31.1% of statements, respectively. For the remaining 31.4% of statements, consensus was reached during a 4-h consensus meeting. CONCLUSIONS: Statements on the management of WSLs derived from a systematic literature review combined with expert opinion were formally integrated toward consensus through a nominal group technique. These statements formed the basis for developing a CPG on the management of WSLs before and during orthodontic treatment.

Cessation of facial growth in subjects with short, average, and long facial types - Implications for the timing of implant placement.

Placement of a single-tooth implant should be performed when a patient's facial growth has ceased. In this retrospective observational study, we evaluated if there was a difference in the timing of cessation of craniofacial growth in short, average, and long facial types. Based on the value of the angle between cranial base and mandibular plane (SN/MP angle), three groups comprising 48 subjects with short facial type (SF; SN/MP ≤28°), 77 with average facial type (AF; SN/MP ≥31.5° and ≤34.5°), and 44 with long facial type (LF; SN/MP ≥38°) were selected. Facial growth was assessed on lateral cephalograms taken at 15.4 years of age, and 2, 5, and 10 years later. Variables were considered to be stable when the difference between two successive measurements was less than 1 mm or 1°. We found no difference between facial types in the timing of cessation of facial growth. Depending on the variable, the mean age when variables became stable ranged from 18.0 years (Is-Pal in LF group) to 22.0 years (SN/MP in LF group). However, facial growth continued at the last follow-up in approximately 20% subjects. This study demonstrates that facial type is not associated with the timing of cessation of facial growth.

[Interdisciplinary orthodontic surgical treatment of children with cleft lip and palate from 9 to 20 years of age]. / Interdisciplinaire orthodontisch-chirurgische behandeling van schisis van 9 tot 20 jaar.

Cleft lip and palate is a common congenital malformation with a prevalence of 1:600 newborns. Children with orofacial clefts are treated by an interdisciplinary team of specialists while parents and child play a key role in their own care process. The orthodontic and facial orthopedic treatment of a child with a cleft takes many years. Children often get bored of the long treatment and this can cause problems with compliance and oral hygiene. Therefore it is advisable to distinguish 5 well-defined stages in the orthodontic treatment and to attempt to have some 'orthodontics free' time in between. The 3 orthodontic treatment phases between the age of 9 and 20 years consist of orthodontic treatment concerning the closing of the cleft with a bone transplant, the treatment of the permanent dentition and, finally, a possible combined orthodontic surgical treatment at the end of the period of growth. Good interdisciplinary collaboration among the different dental disciplines is essential in this regard.

Transverse dental arch relationship at 9 and 12 years in children with unilateral cleft lip and palate treated with infant orthopedics: a randomized clinical trial (DUTCHCLEFT).

OBJECTIVE: A long-term evaluation to assess the transverse dental arch relationships at 9 and 12 years of age in unilateral cleft lip and palate treated with or without infant orthopedics (IO). The hypothesis is that IO has no effect on the transverse dental arch relationship. MATERIAL AND METHODS: A prospective two-arm randomized controlled trial (DUTCHCLEFT) in three academic cleft palate centers (Amsterdam, Nijmegen and Rotterdam, the Netherlands). Fifty-four children with complete unilateral cleft lip and palate and no other malformations were enrolled in this evaluation. One group wore passive maxillary plates (IO+) during the first year of life, and the other group did not (IO-). Until the age of 1.5, all other interventions were the same. Hard palate was closed simultaneously with bone grafting according to protocol of all teams. Orthodontic treatment was performed when indicated. The transverse dental arch relationship was assessed on dental casts using the modified Huddart/Bodenham score to measure the maxillary arch constriction at 9 and 12 years of age. RESULTS: No significant differences were found between the IO+ and IO- groups. Differences between the centers increased from 9 to 12 years of age. CONCLUSIONS: Transverse dental arch relationships at 9 and 12 years of age do not differ between children with UCLP treated with or without IO. CLINICAL RELEVANCE: There is no orthodontic need to perform IO as applied in this study in children with UCLP.

Stability of Le Fort I maxillary inferior repositioning surgery with rigid internal fixation: a systematic review.

The aim of this study was to evaluate the stability of Le Fort I maxillary inferior repositioning surgery in patients with a vertical maxillary deficiency at least 6 months after surgery. The electronic databases were searched to identify all articles reporting the long-term effects of one-piece maxillary inferior repositioning with rigid fixation. Methodological quality was evaluated according to 15 criteria related to study design, measurements, and statistical analysis. Two articles were identified, with a total of 22 patients. The maxilla was repositioned inferiorly from a mean 3.2 to 4.5mm in the anterior part and from a mean 0.1 to 1.8mm in the posterior part. At 6 months post-treatment, absolute relapse of a mean 1.6mm was measured for the anterior part of the maxilla and 0.3mm for the posterior part of the maxilla. The stability of maxillary inferior repositioning surgery could not be confirmed due to the small sample size, unclear diagnosis, and potential confounding factors.

[Tooth eruption disturbances and syndromes]. / Eruptiestoornissen en syndromen.

In the tooth eruption mechanism, various disturbances can appear as a result of gene mutations, a consequence of which can be that tooth eruption does not occur. There are 5 syndromes which involve the complete failure of several or even all teeth to erupt, specifically: cleidocranial dysplasia, Gardner's syndrome, osteopetrosis, mucopolysaccharidosis and GAPO syndrome. Some are very rare and will seldom be encountered in a dental practice, but they show how vulnerable the tooth eruption mechanism is. Dentists are generally the ones who identify a tooth eruption problem in a patient. Since syndromes can be associated with other disorders, additional investigation by a clinical geneticist is always important when a syndrome is suspected.

Geometric morphometric analysis of craniofacial variation, ontogeny and modularity in a cross-sectional sample of modern humans.

This investigation aimed to quantify craniofacial variation in a sample of modern humans. In all, 187 consecutive orthodontic patients were collected, of which 79 were male (mean age 13.3, SD 3.7, range 7.5-40.8) and 99 were female (mean age 12.3, SD 1.9, range 8.7-19.1). The male and female subgroups were tested for differences in mean shapes and ontogenetic trajectories, and shape variability was characterized using principal component analysis. The hypothesis of modularity was tested for six different modularity scenarios. The results showed that there were subtle but significant differences in the male and female Procrustes mean shapes. Males were significantly larger. Mild sexual ontogenetic allometric divergence was noted. Principal component analysis indicated that, of the four retained biologically interpretable components, the two most important sources of variability were (i) vertical shape variation (i.e. dolichofacial vs. brachyfacial growth patterns) and (ii) sagittal relationships (maxillary prognatism vs. mandibular retrognathism, and vice versa). The mandible and maxilla were found to constitute one module, independent of the skull base. Additionally, we were able to confirm the presence of an anterior and posterior craniofacial columnar module, separated by the pterygomaxillary plane, as proposed by Enlow. These modules can be further subdivided into four sub-modules, involving the posterior skull base, the ethmomaxillary complex, a pharyngeal module, and the anterior part of the jaws.

Development and reproducibility of a 3D stereophotogrammetric reference frame for facial soft tissue growth of babies and young children with and without orofacial clefts.

The aim of this study was to develop a reference frame for three dimensional (3D) facial soft tissue growth analysis in children and to determine its reproducibility. Two observers twice placed the reference frame on 39 3D-stereophotogrammetry facial images of children with orofacial clefts and control children. The observers' performances were analyzed by calculating mean distance, distance variability, and P95 between the same facial surfaces at two different time points. Correlations between observers were analyzed with Pearson's correlation coefficient. The influence of presence of a cleft, absence of one ear in the photograph, and age on the reproducibility of the reference frame was checked using Student's t test. Results of intraobserver comparisons showed a mean distance of <0.40 mm, distance variability of <0.51 mm, and P95 of <0.80 mm. For interobserver reliability, the mean distance was <0.52 mm, distance variability was <0.53 mm, and P95 was <1.10 mm. Presence of a cleft, age, and absence of one ear on the 3D photograph did not have a significant influence on the reproducibility of placing the reference frame. The children's reference frame is a reproducible method to superimpose on 3D soft tissue stereophotogrammetry photographs of growing individuals with and without orofacial clefts.