Intraduodenal nutrient infusion differentially alters intestinal nutrient sensing, appetite, and satiety responses in lean and obese subjects.

BACKGROUND: Intestinal nutrient sensing regulates food intake and energy metabolism by acting locally and relaying nutritional status to the brain. It is unclear whether these mechanisms are altered in obese humans. OBJECTIVES: We aimed to investigate differences in duodenal nutrient sensing in humans with or without obesity and the effects of transiently blocking vagal transmission on nutrient sensing, hunger, and appetite. METHODS: In a single-blinded, randomized, cross-over design, subjects with or without obesity (n = 14 and n = 11, respectively) were infused intraduodenally with saline or a combination of glucose and oleic acid for 90 min (glucose load: 22.5 g, 1 kcal/min; oleic acid load: 10 g, 1 kcal/min) in the presence or absence of local anesthetic (benzocaine). Blood was sampled at 10-min intervals (120-240 min) and 15-min intervals until termination of the study for measurements of gut hormones, insulin, leptin, and C-peptide. Hunger and satiety sensations were scored using the visual analog scale, and hepatic glucose production and glucose oxidation rates were measured. RESULTS: Duodenal nutrient infusion in lean subjects led to a 65% drop in acyl ghrelin release and robustly increased cholecystokinin 8 (CCK-8) release (65%; P = 0.023); benzocaine infusion delayed this response (2-factor repeated-measures analysis of variance, P = 0.0065). In contrast, subjects with obesity had significantly blunted response to nutrient infusion, and no further effects were observed with benzocaine. Additionally, significant delays were observed in peptide YY (3-36), pancreatic polypeptide, glucose inhibitory peptide, and glucagon-like peptide 1 (7-36) response. No significant interactions were found between body mass index (BMI) or baseline hormone levels and areas under the curve for hormones except CCK-8 (BMI, P = 0.018; baseline CCK, P = 0.013). Nutrient-induced hunger and satiety sensations were impeded by benzocaine only in the lean cohort. Hunger and satiety sensations in subjects with obesity were not responsive to nutrient entry into the duodenum, and no additional effects were observed by blocking neural signaling. CONCLUSION: Nutrient-induced gut hormone release and response to transient vagal blockade are significantly blunted in subjects with obesity. This trial was registered at clinicaltrials.org as NCT02537314.

Three-dimensional digital assessment of typodont activations.

OBJECTIVES: Wax typodonts are widely used as pre-clinical teaching tools to test and research the complex force systems created by archwire activations, however, a limitation is the inability to quantify the resultant statically indeterminate tooth movements. The aim of this study was to develop an analogue-to-digital typodont system to quantify the effects of archwire activations on individual typodont teeth in three dimensions. METHODS: The typodont system was developed using CAD/CAM technology. Posterior expansion, squared, tapered, asymmetrical arch forms and reversed curve of Spee activations were tested with three repeats. The resulting three-dimensional movements of individual typodont teeth were assessed with six degrees of freedom (df). Cartesian coordinate systems were set for each tooth. Mesio-distal, bucco-lingual and intrusive-extrusive movements were assessed as changes in the location of the geometrically estimated centre of resistance in the x, y and z axes, respectively. Torque, tip and rotation movements were assessed as the rotations around the mesio-distal, bucco-lingual and intrusive-extrusive axes, respectively. RESULTS: Individual typodont tooth displacements from each activation could reliably be described with six df. The transversal-to-sagittal movement ratio ranged from 2:1 to 7:1, depending on the activation. Asymmetrical arch form activations caused a midline shift and affected the lateral overjet. Reversing the curve of Spee led to intrusion of incisors and second molars, extrusion of premolars and first molars and pronounced first and third order effects. CONCLUSION: The digital typodont system is a promising teaching tool. The tested activations have implications in three dimensions, which should be considered when planning tooth movements.

Caloric Restriction and Weight Loss Are Primary Factors in the Early Tissue-Specific Metabolic Changes After Bariatric Surgery.

OBJECTIVE: To evaluate changes in insulin sensitivity, hormone secretion, and hepatic steatosis immediately after caloric restriction, vertical sleeve gastrectomy (VSG), and Roux-en-Y gastric bypass (RYGB). RESEARCH DESIGN AND METHODS: Obese subjects were assessed for 1) insulin sensitivity with hyperinsulinemic-euglycemic clamp with glucose tracer infusion, 2) adipokine concentrations with serum and subcutaneous adipose interstitial fluid sampling, and 3) hepatic fat content with MRI before and 7-10 days after VSG, RYGB, or supervised caloric restriction. RESULTS: Each group exhibited an ∼5% total body weight loss, accompanied by similar improvements in hepatic glucose production and hepatic, skeletal muscle, and adipose tissue insulin sensitivity. Leptin concentrations in plasma and adipose interstitial fluid were equally decreased, and reductions in hepatic fat were similar. CONCLUSIONS: The improvements in insulin sensitivity and adipokine secretion observed early after bariatric surgery are replicated by equivalent caloric restriction and weight loss.

Botulinum Injection Into the Proximal Intestinal Wall of Diet-Induced Obese Mice Leads to Weight Loss and Improves Glucose and Fat Tolerance.

Botulinum neurotoxin (available commercially as BOTOX) has been used successfully for treatment of several neuromuscular disorders, including blepharospasm, dystonia, spasticity, and cerebral palsy in children. Our data demonstrate that injection of Botox into the proximal intestinal wall of diet-induced obese (DIO) mice induces weight loss and reduces food intake. This was associated with amelioration of hyperglycemia, hyperlipidemia, and significant improvement of glucose tolerance without alteration of energy expenditure. We also observed accelerated gastrointestinal transit and significant reductions in glucose and lipid absorption, which may account, at least in part, for the observed weight loss and robust metabolic benefits, although possible systemic effects occurring as a consequence of central and/or peripheral signaling cannot be ignored. The observed metabolic benefits were found to be largely independent of weight loss, as demonstrated by pair-feeding experiments. Effects lasted ∼8 weeks, for as long as the half-life of Botox as reported in prior rodent studies. These results have valuable clinical implications. If the observed effects are translatable in humans, this approach could lay the foundation for therapeutic approaches geared toward robust and sustained weight loss, mimicking some of the benefits of bariatric operations without its cost and complications.

Biomechanical properties of the lips in a pre-orthodontic sample of adolescents and young adults.

OBJECTIVES: To assess biomechanical properties of the lip muscles and to investigate their relationship with sex, age, body mass index (BMI), and cephalometric variables. MATERIALS AND METHODS: Demographic information and BMI were collected from 83 study participants seeking orthodontic treatment at the University of Otago. Tone, stiffness, and elasticity of the lip muscles were measured thrice at four different anatomical sites using a digital palpation device. To estimate method error, a duplicate set of measurements in a subsample of 20 participants was taken a week later. Sagittal and vertical cephalometric classifications were based on ANB and FMPA angles, respectively. Data were analysed using mixed models. RESULTS: Biomechanical properties of lip muscles were remarkably consistent both within and between different recording sessions. The lower lip had higher tone and stiffness than the upper lip. Both the upper and lower lip stiffness and tone were higher in females than in males, whereas upper lip elasticity was higher in males. Thinner upper lips had higher tone and were stiffer than thicker upper lips, whereas thinner lower lips were less elastic than thicker lower lips. Muscle tone and stiffness of both the upper and lower lips were lower in Class III than in Class I and Class II individuals. The upper lip of hyperdivergent individuals was less elastic than that of normodivergent and hypodivergent individuals, and stiffer than that of hypodivergent individuals. CONCLUSIONS: The biomechanical properties of perioral soft tissues can be reliably measured and vary with anatomical site, sex, and cephalometric measurements.

Riboceine Rescues Auranofin-Induced Craniofacial Defects in Zebrafish.

Craniofacial abnormalities are a common group of congenital developmental disorders that can require intensive oral surgery as part of their treatment. Neural crest cells (NCCs) contribute to the facial structures; however, they are extremely sensitive to high levels of oxidative stress, which result in craniofacial abnormalities under perturbed developmental environments. The oxidative stress-inducing compound auranofin (AFN) disrupts craniofacial development in wildtype zebrafish embryos. Here, we tested whether the antioxidant Riboceine (RBC) rescues craniofacial defects arising from exposure to AFN. RBC rescued AFN-induced cellular apoptosis and distinct defects of the cranial cartilage in zebrafish larvae. Zebrafish embryos exposed to AFN have higher expression of antioxidant genes gstp1 and prxd1, with RBC treatment partially rescuing these gene expression profiles. Our data suggest that antioxidants may have utility in preventing defects in the craniofacial cartilage owing to environmental or genetic risk, perhaps by enhancing cell survival.

Factors associated with orthodontic pain.

BACKGROUND: Pain experienced at teeth during orthodontic treatment varies largely over time, with the reasons for its interindividual variability being largely unknown: age, sex, clinical activations, psychosocial factors and genetic polymorphisms of candidate genes are putative factors that may account to explain this variability. We aimed to investigate the effect of clinical, demographic, psychological and genetic factors on pain levels experienced during fixed orthodontic treatment. METHODS: A convenience sample of 183 patients undergoing full-fixed orthodontic treatment were recruited. Participant's pain levels were assessed seven times over a three-day period via a smartphone app. Clinical, demographic and psychological data were collected via questionnaires. This included the Pain Catastrophising Scale (Child version), the Corah Dental Anxiety Scale and the State and Trait Anxiety Inventory. Participants provided a DNA sample either in the form of blood or saliva, which were used for genotyping COMT gene rs6269, rs4680, rs4646310, NR3C1 gene rs2963155 and the HTR2A gene rs9316233. RESULTS: Bond ups had the greatest influence on perceived levels of pain experienced on teeth during orthodontic treatment, accounting for over 20% of total variance in pain response. High-pain responders had higher scores on pain catastrophising (magnification subscale). Self-reported pain during fixed orthodontic treatment was not influenced by sex, age, time into treatment, anxiety, nor by polymorphisms of COMT, HTR2A or NR3C1 genes. CONCLUSIONS: Pain on teeth resulting from orthodontic fixed appliances is stronger during bonds-up and in patients with high catastrophising scores. Demographics, type of clinical activations and the genetic polymorphisms investigated in this research had little or no impact on perceived pain levels.

An Intermittent Fasting Mimicking Nutrition Bar Extends Physiologic Ketosis in Time Restricted Eating: A Randomized, Controlled, Parallel-Arm Study.

There has been increasing interest in time-restricted eating to attain intermittent fasting's metabolic benefits. However, a more extended daily fast poses many challenges. This study was designed to evaluate the effects of a 200-calorie fasting-mimicking diet (FMD) energy bar formulated to prolong ketogenesis and mitigate fasting-associated side effects. A randomized, controlled study was conducted comparing the impact of consuming an FMD bar vs. continued water fast, after a 15-h overnight fast. Subjects in the FMD group showed a 3-h postprandial beta-hydroxybutyrate (BHB) level and 4-h postprandial BHB area under the curve (AUC0-4) that were non-inferior to those who continued with the water fast (p = 0.891 and p = 0.377, respectively). The postprandial glucose AUC0-4 in the FMD group was non-inferior to that in the water fast group (p = 0.899). A breakfast group served as a control, which confirmed that the instrument used in home glucose and ketone monitoring functioned as expected. The results indicate that FMD bar consumption does not interfere with the physiological ketogenesis associated with overnight fasting and could be used to facilitate the practice of time-restricted eating or intermittent fasting.

Common variants of EDA are associated with non-syndromic hypodontia.

OBJECTIVE: The aim of this case-control study was to investigate the association between non-syndromic hypodontia and nineteen common variants of candidate genes ectodysplasin A (EDA), paired box 9 (PAX9), msh homeobox 1 (MSX1) and axis inhibition protein 2 (AXIN2). SETTINGS AND SAMPLE POPULATION: Sixty-one hypodontia cases were frequency-matched to 253 controls with no missing teeth (excluding the third molars). MATERIAL AND METHODS: Self-report data and DNA samples were collected from each participant. RESULTS: The sample had a mean age of 16.6 years (SD = 7.3), with most participants being female (59.6%), and of New Zealand European origin (75.4%). Using multiple logistic regression analysis, it was found that the T-allele of rs12853659 (EDA) and the G-allele of rs2428151 (EDA) were both associated with a higher risk of hypodontia (odds ratio, OR = 2.79, 95% CI = 1.11-7.01; and OR = 2.87, 95% CI = 1.04-7.94, respectively). The G-allele of rs2520378 (EDA) showed a protective effect with an OR of 0.61 (95% CI = 0.38-0.99). The EDA SNP findings were consistent with previous reports included in a meta-analysis. No associations were found with the PAX9, AXIN2 and MSX1 genes, after adjusting for sex and ethnicity. CONCLUSIONS: Common variants of the EDA genes are associated with specific phenotypes of non-syndromic hypodontia, thus confirming their role in the regulatory pathways of normal tooth development. However, larger samples are needed to investigate the association further.

Evaluation of objective and subjective treatment outcomes in orthodontic cases treated with extraction of a mandibular incisor.

OBJECTIVES: To analyze changes in occlusal characteristics following mandibular incisor extractions (MIE), to determine the usefulness of wax setups in treatment planning MIE cases and to compare the pre- and posttreatment dental attractiveness between MIE cases and nonextraction (NE) controls. MATERIALS AND METHODS: The Peer Assessment Rating (PAR) Index was used to score pre- and posttreatment dental casts of MIE cases (n = 14) and matched NE controls (n = 14). Occlusal characteristics were evaluated on diagnostic wax setups and posttreatment casts. Attractiveness of pre- and posttreatment cases judged on intraoral photographs of cases (n = 6) and controls (n = 6) were rated by 76 dental students and 10 laypeople using visual analogue scales (VAS). RESULTS: The difference in PAR score reduction (%) between the MIE and NE groups was not significant. Between the wax setup and posttreatment casts, there were moderate correlations in overjet, overbite, and right canine classification. There was no significant difference in pre- and posttreatment change in VAS scores (%) for attractiveness between the MIE (49.8 ± 4.3 [S.E.]) and control groups (40.8 ± 4.3 [S.E.]). However, there was a significant difference (P = .000) between the observer groups. CONCLUSIONS: There were no significant differences in the treatment outcomes of orthodontic cases treated with MIE or NE, indicating that MIE is a valid treatment option. A wax setup is moderately correlated with posttreatment results. Both laypeople and dental students rated posttreatment dental attractiveness higher than pretreatment in MIE and NE groups. Dental students tended to be more critical than laypeople in their ratings.

Some orthodontists' experiences of volunteering for a community orthodontic initiative.

INTRODUCTION: In society, dental professionals, including orthodontists, are often viewed as being solely motivated by money. Nevertheless, numerous orthodontists volunteer for community initiatives where they provide free or heavily subsidized treatment for underserved populations. This study explores the motivations of a group of New Zealand orthodontists who volunteered for one of these initiatives, Wish For A Smile (WFAS), as well as the high and low points of this work. METHODS: Qualitative telephone interviews were conducted with 11 orthodontists who volunteer for WFAS. An inductive data analysis of the data was undertaken and a descriptive qualitative method was chosen. RESULTS: Most participants volunteered for WFAS because they desired to give back to the community. High points of their voluntary work were seeing patients' self-esteem, happiness, and future life chances increase as a result of treatment. Low points included seeing the challenging life circumstances of some WFAS patients and treating some adolescents who appeared not to qualify. A number of participants said WFAS patients were more grateful and cooperative than fee-paying patients, whereas others reported the opposite. CONCLUSIONS: There are many reasons why orthodontists volunteer for orthodontic community initiatives, although many may be motivated by a sense of social responsibility to give back to the community.

Role of Bile Acids and GLP-1 in Mediating the Metabolic Improvements of Bariatric Surgery.

BACKGROUND & AIMS: Bile diversion to the ileum (GB-IL) has strikingly similar metabolic and satiating effects to Roux-en-Y gastric bypass (RYGB) in rodent obesity models. The metabolic benefits of these procedures are thought to be mediated by increased bile acids, although parallel changes in body weight and other confounding variables limit this interpretation. METHODS: Global G protein-coupled bile acid receptor-1 null (Tgr5-/-) and intestinal-specific farnesoid X receptor null (FxrΔ/E) mice on high-fat diet as well as wild-type C57BL/6 and glucagon-like polypeptide 1 receptor deficient (Glp-1r-/-) mice on chow diet were characterized following GB-IL. RESULTS: GB-IL induced weight loss and improved oral glucose tolerance in Tgr5-/-, but not FxrΔ/E mice fed a high-fat diet, suggesting a role for intestinal Fxr. GB-IL in wild-type, chow-fed mice prompted weight-independent improvements in glycemia and glucose tolerance secondary to augmented insulin responsiveness. Improvements were concomitant with increased levels of lymphatic GLP-1 in the fasted state and increased levels of intestinal Akkermansia muciniphila. Improvements in fasting glycemia after GB-IL were mitigated with exendin-9, a GLP-1 receptor antagonist, or cholestyramine, a bile acid sequestrant. The glucoregulatory effects of GB-IL were lost in whole-body Glp-1r-/- mice. CONCLUSIONS: Bile diversion to the ileum improves glucose homeostasis via an intestinal Fxr-Glp-1 axis. Altered intestinal bile acid availability, independent of weight loss, and intestinal Akkermansia muciniphila appear to mediate the metabolic changes observed after bariatric surgery and might be manipulated for treatment of obesity and diabetes.

Iran's Health Reform Plan: Measuring Changes in Equity Indices.

BACKGROUND: Two years after the implementation of the Health Sector Evolution Plan (HSEP), this study evaluated the effects of the plan on health equity indices. METHODS: The main indices assessed by the study were the Out-of-Pocket (OOP) health expenditures, the Fairness in Financial Contribution (FFC) to the health system index, the index of households' Catastrophic Health Expenditure (CHE) and the headcount ratio of Impoverishing Health Expenditure (IHE). RESULTS: The per capita share of costs for total health services has been decreased. The lowered costs have been more felt in rural areas, generally due to sharp decrease in inpatient costs. Per capita pay for outpatient services is almost constant or has slightly increased. The reform plan has managed to improve households' Catastrophic Health Expenditure (CHE) index from an average of 2.9% before the implementation of the plan to 2.3% after the plan. The Fairness in Financial Contribution (FFC) to the health system index has worsened from 0.79 to 0.76, and the headcount ratio of Impoverishing Health Expenditure (IHE) index deteriorated after the implementation of plan from 0.34 to 0.50. CONCLUSION: Considerable improvement, in decreasing the burden of catastrophic hospital costs in low income strata which is about 26% relative to the time before the implementation of the plan can be regarded as the main achievement of the plan, whereas the worsening in the headcount ratio of IHE and FFC are the equity bottlenecks of the plan.

Long-term changes in oral health-related quality of life of standard, cleft, and surgery patients after orthodontic treatment: A longitudinal study.

INTRODUCTION: The aim of this study was to assess long-term changes and describe the trajectories of oral health-related quality of life (OHRQoL) in a cohort of cleft, surgery, and standard patients who received orthodontic treatment. METHODS: Standard (n = 16), cleft (n = 19), and orthognathic surgery (n = 22) patients completed the short-form of the Oral Health Impact Profile (OHIP-14) before treatment, immediately posttreatment, and approximately 5 years posttreatment. RESULTS: An overall reduction in OHIP-14 scores (improvement in OHRQoL) occurred after orthodontic treatment; however, this was only significant for the surgery and standard groups (P <0.05). The total OHIP-14 score increased significantly from posttreatment to 5 years follow-up for all 3 study groups (P <0.05). Relative to pretreatment, however, there were significant reductions in total OHIP-14 scores at 5 years posttreatment in the surgery group (-57.4%; P <0.05), but not in the standard sample (-24.2%; P >0.05). By contrast, the OHIP-14 score in the cleft group increased but not significantly (40.2%; P >0.05). Using a mixed model analysis, a significant interaction was detected between patient group and time (ie, study time point) (F = 6.0; P <0.0001), after adjusting for age and sex. CONCLUSIONS: Distinct patient groups showed different OHRQoL trajectories after orthodontic treatment. Treatment-related improvements in OHRQoL are maintained over time for surgery patients, but not for those with standard malocclusions and orofacial clefts.

Impact of skeletal divergence on oral health-related quality of life and self-reported jaw function.

OBJECTIVE: To investigate the differences in oral health-related quality of life (OHRQoL) and self-reported jaw function between patients with hyperdivergent and normodivergent facial types. METHODS: Eighty patients with a distinctively hyperdivergent facial type (mandibular plane angle greater than 2 standard deviations, or 42°) and 80 controls were individually matched according to age, sex, ethnicity, and treatment stage. Data were collected using self-report questionnaires such as the Oral Health Impact Profile (OHIP-14) and Jaw Functional Limitation Scale (JFLS-8). RESULTS: The mean age of the patients was 17.2 ± 4.6 years (range, 12-9 years), with most (65.0%) being female and of New Zealand European origin (91.3%). Individuals with hyperdivergent facial types had higher overall and social domain scores on the OHIP-14 (p < 0.05) than did the ones with normodivergent facial types. However, the intergroup differences in JFLS-8 scores were not significant (p > 0.05). CONCLUSIONS: Jaw function appears to be similar in individuals with hyperdivergent and normodivergent facial morphologies. However, those with hyperdivergent facial types are more likely to self-report poorer OHRQoL than are those with normal faces, especially in relation to social aspects.

Effect of orthodontic treatment on the periodontal tissues.

Reduced periodontal support is a challenge that clinicians often face during rehabilitation of compromised dentition. The close and intricate relationship between the periodontal tissues and the processes of tooth movement suggest that adjunct orthodontic therapy may play an important role in overcoming these problems. On the other hand, excessive movement of teeth beyond the anatomic boundaries of the alveolar process is commonly believed to contribute to further destruction of the periodontal tissues. This review evaluates the clinical effects of various orthodontic tooth movements on the surrounding periodontal soft tissues and alveolar bone. Another objective was to identify possible patient and treatment-related factors that may influence the response of periodontal tissue to specific orthodontic treatments. Particular emphasis is placed on specific tooth movements, such as extrusion, intrusion, space closure and arch expansion. Limitations of current research are also highlighted and discussed.

Hypodontia: An Update on Its Etiology, Classification, and Clinical Management.

Hypodontia, or tooth agenesis, is the most prevalent craniofacial malformation in humans. It may occur as part of a recognised genetic syndrome or as a nonsyndromic isolated trait. Excluding third molars, the reported prevalence of hypodontia ranges from 1.6 to 6.9%, depending on the population studied. Most affected individuals lack only one or two teeth, with permanent second premolars and upper lateral incisors the most likely to be missing. Both environmental and genetic factors are involved in the aetiology of hypodontia, with the latter playing a more significant role. Hypodontia individuals often present a significant clinical challenge for orthodontists because, in a number of cases, the treatment time is prolonged and the treatment outcome may be compromised. Hence, the identification of genetic and environmental factors may be particularly useful in the early prediction of this condition and the development of prevention strategies and novel treatments in the future.

Metabolic responses to exogenous ghrelin in obesity and early after Roux-en-Y gastric bypass in humans.

AIMS: Ghrelin is a gastric-derived hormone that stimulates growth hormone (GH) secretion and has a multi-faceted role in the regulation of energy homeostasis, including glucose metabolism. Circulating ghrelin concentrations are modulated in response to nutritional status, but responses to ghrelin in altered metabolic states are poorly understood. We investigated the metabolic effects of ghrelin in obesity and early after Roux-en-Y gastric bypass (RYGB). MATERIALS AND METHODS: We assessed central and peripheral metabolic responses to acyl ghrelin infusion (1 pmol kg-1 min-1 ) in healthy, lean subjects (n = 9) and non-diabetic, obese subjects (n = 9) before and 2 weeks after RYGB. Central responses were assessed by GH and pancreatic polypeptide (surrogate for vagal activity) secretion. Peripheral responses were assessed by hepatic and skeletal muscle insulin sensitivity during a hyperinsulinaemic-euglycaemic clamp. RESULTS: Ghrelin-stimulated GH secretion was attenuated in obese subjects, but was restored by RYGB to a response similar to that of lean subjects. The heightened pancreatic polypeptide response to ghrelin infusion in the obese was attenuated after RYGB. Hepatic glucose production and hepatic insulin sensitivity were not altered by ghrelin infusion in RYGB subjects. Skeletal muscle insulin sensitivity was impaired to a similar degree in lean, obese and post-RYGB individuals in response to ghrelin infusion. CONCLUSIONS: These data suggest that obesity is characterized by abnormal central, but not peripheral, responsiveness to ghrelin that can be restored early after RYGB before significant weight loss. Further work is necessary to fully elucidate the role of ghrelin in the metabolic changes that occur in obesity and following RYGB.

Management of missing mandibular second premolars: a review.

Tooth agenesis is the most common developmental dental anomaly and it is frequently associated with other dento-skeletal disturbances, such as structural variations of other teeth, late dental eruption, transpositions and crowding. Except for the third molars, the mandibular second premolars are the most commonly missing teeth. Oral rehabilitation of patients with missing mandibular premolars often requires a multi-disciplinary approach, and usually results in prolonged treatment time and a greater burden of care. An understanding of the aetiology and clinical features of hypodlontia is essential for the planning phase and the outcome of treatment. The purpose of the present review is, therefore, to discuss the aetiology of hypodlontia as well as to evaluate the clinical options available for the treatment of missing mandibular second premolars. An insight into future research directions and their clinical applications will also be discussed.

Morphometric growth changes of the nasopharyngeal space in subjects with different vertical craniofacial features.

INTRODUCTION: The purpose of this study was to morphometrically investigate the growth pattern of the adenoids in growing subjects with hyperdivergent and hypodivergent vertical craniofacial features. METHODS: In this retrospective study, we used a longitudinal sample of lateral cephalometric radiographs of 28 hyperdivergent and 30 hypodivergent subjects from 4 to 13 years of age. The radiographs were obtained from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection. Measurements were made using digital tracings of the lateral cephalograms and point distribution models. Mixed-model analyses were used for statistical analysis. RESULTS: The mean distance between the sphenoid bone and the posterior nasal spine increased up to 5.3 mm over a 9-year span (95% CI, 4.1-6.5 mm; P <0.001). Furthermore, the mean distance between the sphenoid bone and the posterior nasal spine differed significantly (P = 0.029) between facial types; it was consistently greater (1.8 mm; 95% CI, 0.2-3.3 mm) in the hyperdivergent group. The nasopharyngeal airway area showed a trend to increase with age up to 12-fold (P <0.001). A significant interaction (P = 0.004) was found between age and facial type. Assessment of the adenoid shapes showed greater convexities in the hyperdivergent group, which were observable from an earlier age and for a longer duration. CONCLUSIONS: Clear differences in the morphometric growth pattern of the adenoids were found between facial types. Evaluation of adenoid shapes showed more prominent convexities that lasted longer in the long facial types than in the short facial types.