Accuracy of cone-beam computed tomography in imaging the components of the periodontal phenotype.

The components and dimensions of the periodontal and peri-implant phenotype have a high relevance in contemporary dental research and should be taken into consideration in the decision-making process in the management of a variety of clinical scenarios to optimize the outcomes of therapy. Various assessment methods for quantifying and classifying the phenotypical dimensions have emerged and developed in recent decades. Nevertheless, the use of cone-beam computed tomography (CBCT) scans remains the most commonly used approach worldwide. However, the accuracy to adequately imaging and measuring the dimensions of the hard and soft tissue components around teeth may represent a significant challenge in different clinical scenarios due to factors such as the age of the patient and motion during the scan, presence of metallic artifacts causing streaks and gray-value distortion, overlapping of soft tissue structures, machine performance, file processing, and small voxel size among others. These factors pose a particular challenge when tiny structures are under investigation, for example, the buccal/lingual bony or soft tissue layer of lower/upper incisors. Therefore, this review addresses the underlying technical information of the use of CBCT scans, and suggests some recommendations on the utilization of this method of assessment to optimally use it despite its' system-inherent limitations.

Reflecting the human lip in vitro: Cleft lip skin and mucosa keratinocytes keep their identities.

OBJECTIVES: Cell models have shown great promise as tools for research, potentially providing intriguing alternatives to animal models. However, the original tissue characteristics must be maintained in culture, a fact that is often assumed, but seldom assessed. We aimed to follow the retention of the original tissue identities of cleft lip-derived skin and mucosa keratinocytes in vitro. METHODS: Cleft lip-derived keratinocytes were isolated from discarded tissue along the cleft margins during cheiloplasty. Cell identities were assessed by immunohistochemistry and quantitative real-time PCR for tissue-specific markers and compared with native lip tissue. Moreover, keratinocytes were regularly analyzed for the retention of the original tissue characteristics by the aforementioned methods as well as by differentiation assays. RESULTS: The various anatomical zones of the human lip could be distinguished using a panel of differentiation and functional-based markers. Using these markers, retention of the original tissue identities could be followed and confirmed in the corresponding primary keratinocytes in culture. CONCLUSIONS: Our findings promote patient-derived cells retaining their original identities as astonishing and clinically relevant in vitro tools. Such cells allow a better molecular understanding of various lip-associated pathologies as well as their modeling in vitro, including but not restricted to orofacial clefts.

Long-term occlusal tooth wear at the onset of permanent dentition.

OBJECTIVES: This study quantified the long-term occlusal wear in the natural posterior teeth and the associations per tooth type within the dentition. METHODS: The sample included 70 orthodontically treated subjects (52 females and 18 males; median age, 14.3 years), followed for a 12.7-year period. They were consecutively selected with no tooth wear-related criteria. Post-treatment (T1) and follow-up dental casts (T2) were scanned and superimposed through three-dimensional methods. Occlusal wear volume of posterior teeth and tooth wear patterns were investigated through non-parametric statistics and analysis of covariance. RESULTS: There were no significant differences between contralateral teeth. The average occlusal wear per posterior tooth was 2.3 mm3, with 65.2% of teeth showing values greater than 1 mm3. Males, mandibular teeth, and first molars exhibited slightly greater wear levels than females (median, 2.57 and 2.21 mm3, respectively; p = 0.005), maxillary teeth, and first or second premolars, respectively. In all first premolars and in the mandibular second premolars, the buccal cusps were primarily affected with no other distinct patterns. There were weak to moderate correlations between tooth types, apart from certain strong correlations detected in males. CONCLUSIONS: Posterior tooth wear was highly prevalent after a 13-year period starting at the onset of permanent dentition. The detected patterns are in accordance with the concept of canine guidance occlusion that is transforming into group synergy through function. CLINICAL RELEVANCE: The widespread tooth wear occurrence and the high intra- and inter-individual variability underline the need for individual patient monitoring to identify high-risk patients at early stages.

Assessment of gingival translucency at the mandibular incisors with two different probing systems. A cross sectional study.

OBJECTIVES: Increasing evidence indicates that the thickness of periodontal soft tissues plays an important role in various clinical scenarios, thus pointing to the need of further clinical research in this area. Aim of the present study was to assess gingival thickness at the mandibular incisors by translucency judgement with two different probes and to validate if these methods are comparable and applicable as diagnostic tools. MATERIALS AND METHODS: A total of 200 participants were included; gingival tissue thickness was measured by judging probe translucency at both central mandibular incisors, mid-facially on the buccal aspect of each tooth using a standard periodontal probe and a set of color-coded probe, each with a different color at the tip, i.e. Colorvue Biotype Probe (CBP). Frequencies and relative frequencies were calculated for probe visibility. Agreement between the standard periodontal probe and the CBP was evaluated via the kappa statistic. RESULTS: When the periodontal probe was visible, the frequency of CBP being visible was very high. Kappa statistic for the agreement between the standard periodontal probe and the CBP was 0.198 (71.5% agreement; p-value < 0.001) for tooth 41 and 0.311 (74.0% agreement; p-value < 0.001) for tooth 31, indicating a positive association of the two methods. CONCLUSIONS: An agreement that reached 74% was estimated between the standard periodontal probe and the color-coded probe at central mandibular incisors.  CLINICAL RELEVANCE: In the context of the present study, the two methods of evaluating gingival thickness seem to produce comparable measurements with a substantial agreement. However, in the 1/4 of the cases, the visibility of the color-coded probe could not assist in the categorization of the gingival phenotype.

Accurate gingival recession quantification using 3D digital dental models.

OBJECTIVES: To develop and validate a method for accurate quantitative assessment of gingival recessions based on superimposition of serial 3D digital models. MATERIALS AND METHODS: Gingival recessions of mild (0.5-2 mm) and increased (3-7 mm) severity were simulated on stone casts and surface models were created. The outlines of the gingival margins of the mild (A) and severe recessions (B) were compared to the original gingival margins following 3D best fit superimposition through a gold standard technique (GS), which used intact adjacent structures, and the tested method (CC), which used single tooth crowns at the position of recessions, as superimposition reference. The primary outcome was the distance between the most apical point of each corresponding gingival margin along the respective tooth long axis. RESULTS: For mild recessions, the median difference of the test methods (CC_A) from the reference method (GS_A) was 0.008 mm (IQR: 0.093; range: - 0.143, 0.147). For severe recessions, the median difference of the test method (CC_B) from the reference method (GS_B) was 0.009 mm (IQR: 0.091; range: - 0.170, 0.198). The proposed method (CC) showed very high intra- and inter-operator reproducibility (median: 0.025 and 0.033 mm, respectively). CONCLUSIONS: The suggested method offers highly accurate monitoring of gingival margin changes and diagnosis of gingival recessions using 3D digital dental models. The method is applicable irrespective of changes in tooth position or form, allowing for assessments over any time span. CLINICAL RELEVANCE: The accurate detection and visualization of gingival margin changes in 3D will enhance diagnosis and patient-doctor communication.

Impact of fixed orthodontic appliances on blood count and high-sensitivity C-reactive protein levels: A prospective cohort study.

INTRODUCTION: The aim was to elucidate the magnitude of alterations in systemic blood counts in healthy patients during the first 14 days after fixed orthodontic appliance placement. METHODS: This prospective cohort study consecutively included 35 White Caucasian patients starting orthodontic treatment with fixed appliances. The mean age was 24.48 ± 6.68 years. All patients were physically and periodontally healthy. Blood samples were collected at 3 time points: (1) baseline (exactly before the placement of appliances), (2) 5 days after bonding, and (3) 14 days after baseline. Whole blood and erythrocyte sedimentation rates were analyzed in automated hematology and erythrocyte sedimentation rate analyzer. Serum high-sensitivity C-reactive protein levels were measured by the nephelometric method. Standardized sample handling and patient preparation procedures were adopted to reduce preanalytical variability. RESULTS: A total of 105 samples were analyzed. All clinical and orthodontic procedures were performed without complications or side effects during the study period. All laboratory procedures were performed per protocol. Significantly lower white blood cell counts were detected 5 days after bracket bonding, compared with baseline (P <0.05). Hemoglobin levels were lower at 14 days than baseline (P <0.05). No other significant shifts or alteration patterns were observed over time. CONCLUSIONS: Orthodontic fixed appliances led to a limited and transient change in white blood cell counts and hemoglobin levels during the first days after bracket placement. The fluctuation of high-sensitivity C-reactive protein levels was not significant, demonstrating a lack of association between systemic inflammation and orthodontic treatment.

Survival of conventionally bonded mandibular retainers with or without enamel sandblasting in orthodontic patients over a 12-month period. A single-centre, split-mouth randomized clinical trial.

BACKGROUND: The aim of this trial was to assess the effect of enamel sandblasting in addition to the acid-etch technique in reducing first-time failures of fixed mandibular retainers placed over a 12-month period. MATERIALS AND METHODS: Ethical approval was obtained. Participants were recruited in a single private practice. The primary outcome of this study was any first-time failure of the mandibular fixed retainer assessed at three timepoints over a 12-month period. Three consecutive teeth either on the left or right side (from lower canine-lower central incisor) were randomly allocated to the intervention (sandblasting) and the control (non-sandblasted). Randomization was performed using a centralized randomization service. The patients were randomized in blocks of four and eight with allocation concealment secured by contacting the sequence generator for group assignment. Blinding of either the patient or clinicians was not possible at time of placement of the mandibular retainer. RESULTS: One hundred and ninety-seven participants were randomized to receive enamel sandblasting (intervention) and non-sandblasting (control) in the region of the six anterior mandibular teeth in a split-mouth fashion. Participants were recruited between December 2018 to October 2020. The data for all participants were analysed resulting in 394 observations. Overall, the risk of first-time failure was 11.4%. No difference in first-time failures was observed between the intervention (sandblasting) and control (non-sandblasting) groups [hazard ratio (HR), 1.05; 95% confidence interval (CI), 0.59, 1.88, P = 0.88]. Males had a higher instant probability of first-time failures (HR, 3.18; 95% CI, 1.65-6.14; P < 0.01). Participants with a fair level of co-operation had a lower instant probability of first-time failures (HR, 0.37; 95% CI, 0.16-0.86; P = 0.02). There were no harms reported to either the participant or their dentition. CONCLUSIONS: No difference in the first-time failures of mandibular bonded retainers placed with conventional etch-bond technique with or without enamel sandblasting was observed. The overall risk of first-time failure was 11.4%. REGISTRATION: This trial was not registered prior to trial commencement.

Effect of combined periodontal and orthodontic treatment of tilted molars and of teeth with intra-bony and furcation defects in stage-IV periodontitis patients: A systematic review.

AIM: To assess the effect of combined periodontal and orthodontic treatment (OT) in stage-IV periodontitis patients. MATERIALS AND METHODS: Three focused questions were addressed using the Population, Intervention, Comparison, Outcome, and Study Design criteria. Randomized controlled trials (RCTs), controlled clinical trials, follow-up studies, case series, and controlled/uncontrolled before/after studies were assessed for inclusion. Primary outcomes included mean changes in pocket probing depth (PPD) and clinical attachment level (CAL). Qualitative synthesis of results was performed and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Out of 916 records, 1 retrospective case series study reported the effect of OT of tilted molars, 2 RCTs and 10 prospective and 2 retrospective case series studies reported the effect of OT of treated intra-bony defects and 0 articles reported the effect of OT of treated furcation defects. Mean PPD changes were reported in 14 articles, and mean CAL changes were reported in 8 articles. Risk of bias was high in both included RCTs, critical in nine articles, and serious in four articles. No articles included patient-reported outcomes, and three articles reported harms/adverse effects. CONCLUSIONS: Evidence is limited by (i) the lack or low number of included studies, (ii) the apparent methodological and clinical heterogeneity, and (iii) the high risk of bias of the retrieved studies. No solid conclusions could be drawn concerning OT in stage-IV periodontitis patients with respect to tilted molars, teeth with treated intra-bony defects, and teeth with treated furcation defects.

Gingival thickness threshold and probe visibility through soft tissue: a cross-sectional study.

OBJECTIVES: The aim was to retrieve the threshold of gingival thickness (GT), where the attribute of gingival translucency through probe visibility was altered. METHODS: In 200 patients, the soft tissue thickness was evaluated at both central mandibular incisors using ultrasound quantification (USD). Additionally, probe visibility was determined using a standard periodontal probe (PB) (CPU 15 UNC, Hu-Friedy), inserted 1 mm deep into the gingival sulcus. Frequencies and relative frequencies were calculated. Repeatability analyses and receiver operating characteristics (ROC) were conducted to determine the USD cut-off point for probe visibility. RESULTS: Regression model indicated that the probe was not visible at a thickness of 0.82 mm for the mandibular left central incisor (95% CIs 0.77, 0.86) and became visible at a thickness of 0.69 mm (95% CIs 0.65, 0.72). The respective values for the mandibular right central incisor were 0.82 mm (95% CIs 0.77, 0.87) and 0.70 mm (0.68, 0.74). ROC analysis confirmed the retrieved regression results by indicating the best fitting balance for specificity and sensitivity at a thickness of 0.8 mm for both mandibular incisors. CONCLUSIONS: In the frame of the current study, the data revealed that gingiva becomes non-transparent at a thickness of approximately 0.8 mm. CLINICAL RELEVANCE: Probe visibility at mandibular incisors for the discrimination between thin and thick soft tissues was correlated with a gingival thickness of 0.8 mm and a high repeatability.

Bone turnover markers in gingival crevicular fluid and blood serum of patients with fixed orthodontic appliances.

AIM: Bone remodelling can be followed through the bone turnover markers (BTMs). Aim of the present study was to record the fluctuation of an osteoclastic and an osteoblastic BTM [C-terminal telopeptide of type I collagen (CTX) and N-terminal pro-peptide of type I pro-collagen (PINP), respectively] in both the gingival crevicular fluid (GCF) and the serum of orthodontic patients before and after the initial application of orthodontic forces. MATERIALS AND METHODS: Twenty-one Caucasian patients were prospectively evaluated. GCF and blood samples were collected in order to measure the selected biomarkers by ELISA at three time-points: exactly before, 5 days, and 14 days after bonding of the appliances. Standardized sample handling and patient preparation procedures were adopted in order to reduce pre-analytical variability. RESULTS: GCF and serum CTX levels were found to be independent of age, although higher in the serum of female subjects. PINP levels were found higher in the serum of patients ≥25 years old, as well as in the GCF of males. A positive correlation between serum and GCF baseline PINP levels was observed. LIMITATIONS: The effect of orthodontic treatment on bone remodelling might not be absolutely representative of the local bone microenvironment as the levels of the specific BTMs where measured within the GCF of the lower front teeth. CONCLUSIONS: This is the first time PINP and CTX have been evaluated in the GCF and serum of orthodontic patients with fixed appliances. No statistically significant alterations of CTX and PINP levels in the GCF and the serum of patients were recorded over time during the initial stages of orthodontic treatment.

Class II Division 1 malocclusion treatment with extraction of maxillary first molars: Evaluation of treatment and post-treatment changes by the PAR Index.

OBJECTIVE: To investigate occlusal result and post-treatment changes after orthodontic extraction of maxillary first permanent molars in patients with a Class II division 1 malocclusion. SETTING AND SAMPLE: Retrospective longitudinal study in a private practice, with outcome evaluation by an independent academic hospital. Ninety-six patients (53 males, 43 females) consecutively treated by one orthodontist with maxillary first permanent molar extraction were studied, divided into three facial types, based on pre-treatment cephalometric values: hypodivergent (n = 18), normodivergent (n = 21) and hyperdivergent (n = 57). METHODS: Occlusal outcome was scored on dental casts at T1 (pre-treatment), T2 (post-treatment) and T3 (mean follow-up 2.5 ± 0.9 years) using the weighted Peer Assessment Rating (PAR) Index. The paired sample t test and one-way ANOVA followed by Tukey's post hoc test were used for statistical analysis. RESULTS: PAR was reduced by 95.7% and 89.9% at T2 and T3, respectively, compared with the start of treatment. The largest post-treatment changes were found for overjet and buccal occlusion. Linear regression analysis did not reveal a clear effect (R-Square 0.074) of age, sex, PAR score at T1, incremental PAR score T2-T1, overjet and overbite at T1, and facial type on the changes after treatment (incremental PAR score T3-T2). CONCLUSIONS: The occlusal outcome achieved after Class II division 1 treatment with maxillary first permanent molar extractions was maintained to a large extent over a mean post-treatment follow-up of 2.5 years. Limited changes after treatment were found, for which no risk factors could be discerned.

Maxillary distraction osteogenesis versus orthognathic surgery for cleft lip and palate patients.

BACKGROUND: Cleft lip and palate is one of the most common birth defects and can cause difficulties with feeding, speech and hearing, as well as psychosocial problems. Treatment of orofacial clefts is prolonged; it typically commences after birth and lasts until the child reaches adulthood or even into adulthood. Residual deformities, functional disturbances, or both, are frequently seen in adults with a repaired cleft. Conventional orthognathic surgery, such as Le Fort I osteotomy, is often performed for the correction of maxillary hypoplasia. An alternative intervention is distraction osteogenesis, which achieves bone lengthening by gradual mechanical distraction. This review is an update of the original version that was published in 2016. OBJECTIVES: To provide evidence regarding the effects and long-term results of maxillary distraction osteogenesis compared to orthognathic surgery for the treatment of hypoplastic maxilla in people with cleft lip and palate. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 15 May 2018), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2018, Issue 4), MEDLINE Ovid (1946 to 15 May 2018), Embase Ovid (1980 to 15 May 2018), and LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; from 1982 to 15 May 2018). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing maxillary distraction osteogenesis to conventional Le Fort I osteotomy for the correction of cleft lip and palate maxillary hypoplasia in non-syndromic cleft patients aged 15 years or older. DATA COLLECTION AND ANALYSIS: Two review authors assessed studies for eligibility. Two review authors independently extracted data and assessed the risk of bias in the included studies. We contacted trial authors for clarification or missing information whenever possible. All standard methodological procedures expected by Cochrane were used. MAIN RESULTS: We found six publications involving a total of 47 participants requiring maxillary advancement of 4 mm to 10 mm. All of them related to a single trial performed between 2002 and 2008 at the University of Hong Kong, but not all of the publications reported outcomes from all 47 participants. The study compared maxillary distraction osteogenesis with orthognathic surgery, and included participants from 13 to 45 years of age.Results and conclusions should be interpreted with caution given the fact that this was a single trial at high risk of bias, with a small sample size.The main outcomes assessed were hard and soft tissue changes, skeletal relapse, effects on speech and velopharyngeal function, psychological status, and clinical morbidities.Both interventions produced notable hard and soft tissue improvements. Nevertheless, the distraction group demonstrated a greater maxillary advancement, evaluated as the advancement of Subspinale A-point: a mean difference of 4.40 mm (95% CI 0.24 to 8.56) was recorded two years postoperatively.Horizontal relapse of the maxilla was significantly less in the distraction osteogenesis group five years after surgery. A total forward movement of A-point of 2.27 mm was noted for the distraction group, whereas a backward movement of 2.53 mm was recorded for the osteotomy group (mean difference 4.8 mm, 95% CI 0.41 to 9.19).No statistically significant differences could be detected between the groups in speech outcomes, when evaluated through resonance (hypernasality) at 17 months postoperatively (RR 0.11, 95% CI 0.01 to 1.85) and nasal emissions at 17 months postoperatively (RR 3.00, 95% CI 0.14 to 66.53), or in velopharyngeal function at the same time point (RR 1.28, 95% CI 0.65 to 2.52).Maxillary distraction initially lowered social self-esteem at least until the distractors were removed, at three months postoperatively, compared to the osteotomy group, but this improved over time and the distraction group had higher satisfaction with life in the long term (two years after surgery) (MD 2.95, 95% CI 014 to 5.76).Adverse effects, in terms of clinical morbidities, included mainly occlusal relapse and mucosal infection, with the frequency being similar between groups (3/15 participants in the distraction osteogenesis group and 3/14 participants in the osteotomy group). There was no severe harm to any participant. AUTHORS' CONCLUSIONS: This review found only one small randomised controlled trial concerning the effectiveness of distraction osteogenesis compared to conventional orthognathic surgery. The available evidence is of very low quality, which indicates that further research is likely to change the estimate of the effect. Based on measured outcomes, distraction osteogenesis may produce more satisfactory results; however, further prospective research comprising assessment of a larger sample size with participants with different facial characteristics is required to confirm possible true differences between interventions.

Gingival recession in orthodontic patients 10 to 15 years posttreatment: A retrospective cohort study.

INTRODUCTION: The aims of this study were to retrospectively investigate the long-term development of gingival recession in a cohort of orthodontic patients and to compare the prevalence of gingival recession in orthodontically treated patients 10 to 15 years posttreatment to that of untreated subjects with malocclusion. METHODS: The sample included 88 patients with mean ages of 12.1 years (SD, 2.4 years) at pretreatment, 15.1 years (SD, 2.4 years) at posttreatment, and 27.9 years (SD, 2.5 years) 10 to 15 years posttreatment. The control group comprised 102 untreated patients seeking orthodontic treatment with a mean age of 28.7 years (SD, 3.1 years). Gingival recession was evaluated on study models. RESULTS: The prevalence of both labial/buccal and lingual/palatal gingival recession increased during orthodontic treatment with further increases during the long-term posttreatment period; 98.9% of the orthodontically treated participants had at least 1 labial/buccal recession, and 85.2% of the patients had at least 1 lingual/palatal recession 10 to 15 years posttreatment. In addition, the proportion of patients with multiple labial/buccal or lingual/palatal recession sites increased considerably in the same time period. The prevalences of labial/buccal gingival recession were similar in the orthodontically treated patients 10 to 15 years posttreatment and the untreated controls. Study group patients with a crossbite before treatment showed 2.73 more recessions (95% CI, 0.28-5.17; P = 0.029) than did those without a transverse discrepancy. Untreated subjects with crowding greater than 3 mm per arch had 3.29 more recessions (95% CI, 0.73-5.68; P = 0.012) to 4.92 more recession sites (95% CI, 1.70-8.15; P = 0.003) than did those with mild or no crowding. CONCLUSIONS: Within the limitations of this study, it seems that, in regard to the prevalence of gingival recession, orthodontically treated patients are not compromised in the long term compared with those with malocclusion that was untreated for many years.

Diagnosis of tooth ankylosis using panoramic views, cone beam computed tomography, and histological data: a retrospective observational case series study.

Objectives: The aim of this study was to determine whether cone beam computed tomography is a reliable radiological method to diagnose tooth ankylosis. Materials and methods: A series of teeth clinically diagnosed as ankylosed were collected after extraction in a private practice from 2009 to 2015 and analyzed retrospectively. Inclusion criteria comprised permanent molars extracted due to failed tooth eruption in the absence of any visible mechanical obstruction, existing panoramic view (PV), and cone beam computed tomography (CBCT) and histological sections of sufficient quality. The CBCT scans and PVs were evaluated twice for signs of ankylosis by two independent observers using the following score: clear signs, possible signs, and no signs. The histological sections were evaluated and graded similarly to the radiographs by a specialist blinded to the radiographs and treatment. Results: Out of an initial group of 22 patients, 9 subjects with 10 affected teeth were included for final evaluation. The age ranged from 8.3 to 17 years. No agreement was seen in comparing the PV scores to the histological sections. Fair to moderate agreement was seen in comparing the CBCT scores to the histological sections. All histologically confirmed ankylosis were detected in CBCT by both observers but some false positive results were found. Limitation: Only a small sample size was available as the disorder is rare. It is difficult to distinguish ankylosis from primary failure of eruption. Conclusion: CBCT images can be a useful adjunctive diagnostic tool to diagnose ankylosed teeth, but cannot be recommended as a single diagnostic modality as false positive results were found.

Gingival recession in mandibular incisors and symphysis morphology-a retrospective cohort study.

Objective: To evaluate if the morphology of the mandibular symphysis is associated with the development of gingival recession. Materials and methods: A cohort of 177 patients was followed longitudinally for up to 5 years post-treatment. Based on the width of the symphysis, participants were divided into three groups: narrow (n = 57); average (n = 63), and wide symphysis (n = 57). Morphology of the symphysis and inclination of incisors were measured on lateral cephalometric radiographs before treatment (Ts), at the end of treatment (T0) and 5 years after treatment (T5). Gingival recession and the change of clinical crown heights in mandibular incisors were measured on plaster models made at TS, T0, and T5. Results: From TS to T5 the change in inclination was comparable in the narrow, average, and wide groups. At T5, gingival labial recession was present in 19.3 per cent of patients with narrow symphysis, 20.6 per cent with average symphysis, and 14 per cent of patients with wide symphysis. The difference was not significant. The mean change of clinical crown height was <1 mm (TS - T5). The regression model showed some evidence that incisor inclination at Ts might have been associated with the change of mean clinical crown height (-2.51, 95% CI: -4.6 to -0.4, P = 0.02). The logistic regression model demonstrated that H1 (Height 1) might be associated with the development of gingival recession (OR = 0.75, 95% CI: 0.58 to 0.96, P = 0.03). Conclusion: Within the limitations of this study, there is no evidence that the overall morphology of the mandibular symphysis is associated with gingival recession development.

Furthering knowledge of seaweed growth and development to facilitate sustainable aquaculture.

Macroalgae (seaweeds) are the subject of increasing interest for their potential as a source of valuable, sustainable biomass in the food, feed, chemical and pharmaceutical industries. Compared with microalgae, the pace of knowledge acquisition in seaweeds is slower despite the availability of whole-genome sequences and model organisms for the major seaweed groups. This is partly a consequence of specific hurdles related to the large size of these organisms and their slow growth. As a result, this basic scientific field is falling behind, despite the societal and economic importance of these organisms. Here, we argue that sustainable management of seaweed aquaculture requires fundamental understanding of the underlying biological mechanisms controlling macroalgal life cycles - from the production of germ cells to the growth and fertility of the adult organisms - using diverse approaches requiring a broad range of technological tools. This Viewpoint highlights several examples of basic research on macroalgal developmental biology that could enable the step-changes which are required to adequately meet the demands of the aquaculture sector.

Intercellular translocation of molecules via plasmodesmata in the multiseriate filamentous brown alga, Halopteris congesta (Sphacelariales, Phaeophyceae).

Despite the high number of studies on the fine structure of brown algal cells, only limited information is available on the intercelluar transportation of molecules via plasmodesmata in brown algae. In this study, plasmodesmatal permeability of Halopteris congesta was examined by observing the translocation of microinjected fluorescent tracers of different molecular sizes. The tip region of H. congesta consists of a cylindrical apical cell, while the basal region is multiseriate. Fluorescein isothiocyanate-dextran (FD; 3, 10, and 20 kDa) and recombinant green fluorescent protein (27 kDa) were injected into the apical cell and were observed to diffuse into the neighboring cells. FD of 40 kDa was detected only in the injected apical cell. The plasmodesmatal size exclusion limit was considered to be more than 20 kDa and less than 40 kDa. The extent of translocation of 3 and 10 kDa FD from the apical to neighboring cells 2 h postinjection was estimated based on the fluorescence intensity. It was suggested that the diffusing capacity of plasmodesmata varied according to molecular size. In order to examine acropetal and/or basipetal direction of molecular movement, 3 and 10 kDa FD were injected into the third cell from the apical cell. Successive observations indicated that the diffusion of fluorescence in the acropetal direction took longer than that in the basipetal direction. No ultrastructural difference in plasmodesmata was noted among the cross walls.

A survey of general dentists regarding orthodontic retention procedures.

AIM: To explore 1. how Swiss general dentists deal with complications associated with fixed orthodontic retainers, 2. collaboration between general dentists and orthodontists with regards to the organization and responsibility for long-term follow-up of orthodontic retainers, and 3. the need for standardized clinical guidelines regarding orthodontic retention. METHODS: A structured questionnaire was sent to 201 randomly selected dentists. They were asked about their experience with retainers, opinions regarding the advantages and disadvantages of different types of retainers, responsibility for patients wearing bonded retention and the communication between orthodontists and general dentists. Statistical analysis was carried out using SPSS software. RESULTS: The response rate was 61 per cent. About 55 per cent of the respondents had had experience with bonding fixed retainers and even more were familiar with their follow-up and repair. In case of complications, dentists usually contacted orthodontists according to the following rule: the more severe the complication, the more intense the communication. Most dentists hesitated to remove retainers when requested to do so by the patient and attempted to convince them to continue wearing them. Retainers bonded to all six anterior teeth were considered more efficient than those bonded to canines only; however, possible side effects (e.g. unwanted changes of the torque) were not well known. 66.4 per cent respondents were willing to take responsibility for patients in retention as early as 6 months after retainer placement. 93.2 per cent respondents would welcome the establishment of standardized guidelines. CONCLUSIONS: Swiss general dentists have good knowledge of orthodontic retention and follow-up procedures. Nevertheless, introduction of clinical guidelines including information on the possible side-effects of bonded retention is justified.

The integration of orthodontic miniscrews under mechanical loading: a pre-clinical study in rabbit.

INTRODUCTION: Orthodontic miniscrews are an increasingly popular choice to achieve absolute anchorage. The temporary use of miniscrews and their recent introduction have limited the debate over the biological aspect of the materials to that of the surface that permeates the field of dental implants. The aim of the present study was to investigate the integration of grade 5 titanium mini-implants with machined or sand blasted acid etched surface (SAE) under mechanical load in a rabbit tibia model of implant integration. METHODS: A total of 64 miniscrews (Ti6Al4V) of 1.5 mm diameter and 6.5 mm length were inserted in the proximal medial surface of each tibia in eight male rabbits aged 6 months. Each tibia received four miniscrews. A 100 g nickel-titanium coil spring (Neosentalloy) was applied between two miniscrews along the main axis while two miniscrews were left unloaded. The removal torque was measured for loaded and unloaded miniscrews after 12 weeks. Two miniscrews were harvested for histology. RESULTS: Removal torque was significantly higher for SAE mini-implants than for machined screws, under both loading conditions. Although no difference in bone to implant contact was observed among the groups, cortical area significantly decreased with both surfaces under loading. CONCLUSIONS: Our data indicate that SAE miniscrews have higher bone retention than MA miniscrews, although the effects of mechanical loading of these devices on cortical bone require further investigations.

Effects of facial tooth movement on the periodontium in rats: a comparison between conventional and low force.

BACKGROUND: Bone dehiscences and gingival recession have been associated with orthodontic arch expansion. The aim of this study was to assess and compare periodontal modelling during application of two force levels. METHODS: The second and third upper molars were orthodontically moved buccally with conventional or low forces for 60 or 90 days in 32 rats. Ten non-treated animals were used as controls. The influence of force level and time on dental, skeletal and periodontal parameters (i.e. height and thickness of gingiva and bone) was assessed on histomicrographs using a mixed linear model. RESULTS: Facial tooth position (725 µm, CI 379-1072 µm, distal root of the third molar) and maxillary skeletal width (295 µm, CI 168-421 µm) differed significantly between force groups. Despite bone apposition at the facial aspects of the moved roots, bone dehiscences were developing and bone thickness was decreasing during facial tooth movement. Development of gingival recession was scarce and in cases with extreme facial tooth movement. No remarkable differences between force levels were found for any of the periodontal parameters. CONCLUSIONS: Facial tooth movement with conventional or low forces resulted in similar modelling of facial alveolar bone and gingiva.