The golden ratio-dispelling the myth.

BACKGROUND: The purpose of this article is to explore the claims often cited in scientific journals regarding the golden ratio, and its proposed link to beauty and idealized forms in nature, including idealized human proportions. MAIN BODY: Claims made in the nineteenth century through to the modern day in the clinical literature do not appear to be supported by evidence. SHORT CONCLUSIONS: There is no convincing evidence that the golden ratio is linked to idealized human proportions or facial beauty. There is currently no evidence to support the use of the golden ratio in orthognathic or facial aesthetic/reconstructive surgical planning or analysis of results.

"Over-reviewing" of research? An analysis of orthodontic reviews.

INTRODUCTION: Research overviews may be undertaken to identify gaps in the literature, evaluate existing systematic reviews (SRs), and summarize evidence. This paper aims to profile overviews that have been conducted in orthodontics and related interventions since 2012 and to evaluate the degree of overlap among these overviews. METHODS: Overviews published between January 1, 2012 and June 20, 2023 were identified using an electronic search involving Google Scholar and PubMed. A descriptive summary was produced, and citation matrices were used to evaluate the percentage of overlap between overviews using corrected covered area and covered area. This was classified as slight, moderate, high, or very high. RESULTS: A total of 35 overviews were identified across a wide range of topics. Eight overviews included <10 SRs; 21 had 10-20 SRs; and 6 included >20 SRs (median no. of SRs per overview, 15; range, 3-62). Meta-analysis was conducted in only 5 overviews. Overlap between overviews on the same topic ranged from slight (2.7%) to very high (53.8%). CONCLUSIONS: Almost all overview topics address treatments and their effects, with a wide variation in the number and quality of SRs included. There is considerable overlap in some orthodontic overviews, suggesting unnecessary duplication and research waste. Researchers should be encouraged to focus on primary data collection to add more high-quality data to SRs, which will ultimately enhance the yield from secondary and tertiary orthodontic research.

Perception of frontal facial images compared with their mirror images: chirality, enantiomorphic discrimination, and relevance to clinical practice.

BACKGROUND: What we think we see consists of models constructed in our brains, which may be constrained, limited and perhaps modified at a cerebral level. Patients may view their mirror image differently to how others and the clinical team view them. Understanding potential variations in perception between real and mirror images is important in clinical practice. The aims were to assess differences in self-perception between frontal facial and mirrored photographs, comparing the results with selfie photographs. METHODS: Facial photographs were taken by one investigator under standardized conditions for preclinical and clinical students. Each student took a selfie photograph at rest and smiling using his/her smartphone. A mirror image was generated for each image. Each student was shown his/her original and mirror image, without being informed which was which. For each pair of images, students were asked to choose which photograph they perceived as more attractive. A set of photographs of a male volunteer was shown to all participants, to choose either the original or mirror image as the more attractive. RESULTS: Most observers preferred the true image of the volunteer (P < 0.05), which may be evidence that most people prefer the true image of others, which is how they normally view them. Most observers preferred their own original photograph in frontal view at rest and smiling (P < 0.05), but preferred the mirror image of their selfie photograph at rest and smiling (P < 0.05). CONCLUSIONS: Significant differences in perceptions of attractiveness between true and mirror-reversed frontal and selfie images were found. Observers preferred their image the way they view themselves in a mirror. The selfie is how other people view an individual. If a selfie is flipped horizontally, that is how an individual sees themselves in a mirror. Most observers preferred the mirror image of their selfie, which is how they would view themselves in a mirror.

"Association between posterior unilateral functional crossbite and asymmetrical spinal flexion: A prospective study".

Background: Unilateral posterior crossbite (UPC) with functional shift is a malocclusion that may have the potential to affect the masticatory function and the flexibility of the spine due to intrinsic occlusal, structural and functional asymmetries sustained by marked asymmetrical muscular activation. Research question: To investigate whether the presence of UPC with functional shift is associated with reverse chewing pattern and altered spine flexion. Methods: Patients with UPC and a control group of patients with normal occlusion were recorded when chewing soft and hard boluses using a Kinesiograph (Myotronics-Noromed Inc., USA) and spine alignment was assessed with an electronic inclinometer Spinal Mouse® system (Idiag AG, Switzerland). Results: There were 87 children with UPC in the patients' group among whom 38, with median (IQR) age 8.0 (7.3-9.3) years, had measurements before and after treatment. The UPC patients showed a higher percentage of anomalous/reverse chewing patterns on the crossbite side compared with a control group (p < 0.001). Moreover, a clear difference was observed between left and right flexion angles of the spine in the patients' group (p < 0.001 and p = 0.001, paired t-test) with the crossbite side being more flexible compared to the non-crossbite side. No such differences were seen in the control group, nor post-treatment for right and left crossbite (p = 0.44 and p = 0.15 respectively, paired t-test). Significance: This study suggests an association between UPC, asymmetrical chewing patterns and asymmetrical flexion of the spine. These results may help improve understanding of any association between dental malocclusions and spine posture and hence aid diagnosis and treatment strategies.

Zonal analysis in contemporary aesthetic orthognathic surgical planning.

BACKGROUND: The purpose of this article is to introduce the concept of zonal analysis in orthognathic surgical planning. CASE PRESENTATION: The importance of developing this concept of facial zonal analysis is because grouping together elements of aesthetic importance in a region in a systematic manner allows for accurate diagnosis and logical treatment planning. An orthognathic case presentation is described to demonstrate this concept. DISCUSSION: The three facial zones described are related in terms of the presenting problem and in relation to the changes envisaged with each planned surgical movement. The importance of developing this concept of facial zonal analysis is because grouping together elements of aesthetic importance in a region in a systematic manner allows for accurate diagnosis and logical treatment planning. Consideration is given to the negative features that require improvement and the positive features that the clinician and patient would prefer not to alter. It also provides an organised tool for postoperative comparison of results. The analysis and synthesis of the information provided from this approach can aid contemporary orthognathic surgical planning.

Exosomes in craniofacial tissue reconstruction.

BACKGROUND: Mesenchymal stem cell (MSC) therapy gained interest among scientists following the discovery of its therapeutic potential. However, their clinical use has been hindered due to their immunogenicity and tumorigenicity. Relatively recently, it has been unveiled that the mechanism by which MSC promote healing is by secreting exosomes. This raised the interest in developing cell-free therapy, avoiding the obstacles that deterred the translation of MSC therapy into clinical practice. REVIEW: This comprehensive narrative review summarises the current understanding of exosome biogenesis and content. Moreover, the existing research on exosome use in bone tissue engineering is discussed. CONCLUSIONS: Exosome-based therapy may provide excellent potential in the field of bone tissue engineering and craniofacial reconstructive surgery. Further investigation is required before the technology can be translated into clinical practice.

Staged Surgical Correction of Severe Panfacial and Transverse Nasal Root Asymmetry in Unicoronal Synostosis.

Nasal asymmetry is widely acknowledged to be one of the most difficult deformities to manage. Most reports in the literature pertain to corrective methods in relation to isolated deformity of the dorsum in the posttraumatic patient. There is a paucity of literature relating to management of nasal radix asymmetry, and still less in the context of severe panfacial asymmetry.

Self-harm, dentofacial features, and bullying.

INTRODUCTION: Self-harm is a growing public health problem. The study aimed to investigate the prevalence of self-harm among a representative sample of school children and the contribution of dentofacial appearance and being bullied because of dentofacial appearance to self-harm. METHODS: This was a cross-sectional study in which a representative sample of eighth-grade students (aged 13-14 years) from randomly selected schools was asked to complete anonymous questionnaires distributed in the classroom. The final sample size was 699 children (339 girls, 360 boys) with a mean age of 13.3 years, representing 1.26% of the target population. RESULTS: The prevalence of self-harm was 26.9% (n = 188), with no statistically significant gender differences (P >0.05). Among all the subjects who reported self-harm, 47.9% (n = 90) reported self-harm because of dentofacial features. A total of 41 subjects reported self-harm because of bullying targeted at dentofacial features, representing around one fifth of subjects who reported self-harm. The 3 most common dentofacial features contributing to self-harm and self-harm as a result of bullying were tooth color and shape, spacing between the teeth or missing teeth, and prominent maxillary anterior teeth. CONCLUSIONS: This study demonstrated a relatively high experience of self-harm reported by adolescent school children, with many reporting self-harm as a result of their dentofacial appearance and bullying because of dentofacial features. The present study provides baseline data to better understand the relationship between self-harm and dentofacial features.

Accelerated orthodontic tooth movement: surgical techniques and the regional acceleratory phenomenon.

BACKGROUND: Techniques to accelerate tooth movement have been a topic of interest in orthodontics over the past decade. As orthodontic treatment time is linked to potential detrimental effects, such as increased decalcification, dental caries, root resorption, and gingival inflammation, the possibility of reducing treatment time in orthodontics may provide multiple benefits to the patient. Another reason for the surge in interest in accelerated tooth movement has been the increased interest in adult orthodontics. REVIEW: This review summarizes the different methods for surgical acceleration of orthodontic tooth movement. It also describes the advantages and limitations of these techniques, including guidance for future investigations. CONCLUSIONS: Optimization of the described techniques is still required, but some of the techniques appear to offer the potential for accelerating orthodontic tooth movement and improving outcomes in well-selected cases.

Is self-harm among orthodontic patients related to dislike of dentofacial features and oral health-related quality of life?

OBJECTIVES: To investigate the relationship between self-reported self-harm and dislike of dentofacial features and oral health-related quality of life (OHRQoL). MATERIALS AND METHODS: Anonymous, self-reporting questionnaires were completed by 699 school children (aged 13-14 years), representing over 1% of the age group in Amman, Jordan. Participants were invited from 23 randomly selected schools in 10 educational directorates. OHRQoL was assessed using the Child Perception Questionnaire (CPQ 11-14). Self-harm was assessed using a constructed self-reporting questionnaire. The relationship between OHRQoL and self-harm was assessed and significant findings were identified at probability of α = 0.05. RESULTS: Over one-quarter of schoolchildren (26.9%, n = 88) admitted self-harming behavior. Self-harm was reported to be due to dislike of dentofacial appearance among 12.9% of participants (n = 90). Higher CPQ 11-14 total scores and individual dimension scores were associated with the presence of self-harm (P < .001). High self-harm incidence was reported among participants who had dentofacial features that affected appearance (P < .001). Among subjects admitting self-harm, the frequency of self-harming behavior ranged from once to over 10 times per year. CONCLUSIONS: Significant relationships were found between self-harm and dislike of dentofacial features and OHRQoL.

Quantitative investigation of the esthetic impact of lip prominence in relation to the esthetic line.

INTRODUCTION: The purpose of this quantitative investigation was to assess the influence of lip prominence in relation to the esthetic line (E-line) on perceived attractiveness and threshold values of desire for treatment. METHODS: The lip prominence of an idealized silhouette male white profile image was altered incrementally between -16 mm to 4 mm from the E-line. The images were rated on a Likert scale by pretreatment orthognathic patients (n = 75), laypeople (n = 75), and clinicians (n = 35). RESULTS: In terms of perceived attractiveness, lips to E-line distance within the ranges of -12 mm to -16 mm and 0-4 mm in relation to the E-line was associated with a reduction in median attractiveness scores to below 4 in the patient and clinician groups of observers; for the lay group, the corresponding ranges were -14 mm to -16 mm and 2-4 mm. Relative lip prominence appears to be viewed as more attractive than lip retrusion. Clinicians were generally least likely to suggest treatment for varying levels of bilabial position. For a number of the images, there was reasonable agreement among clinicians and laypeople regarding whether treatment is required. For the clinician group, the only categories for desire for treatment were at a lip to E-line distance within the ranges of -14 mm to -16 mm and 2-4 mm. CONCLUSIONS: It is recommended that the range of normal variability of the prominence of the lips and threshold values of the desire for treatment be considered in planning.

Three-dimensional virtual surgical planning (3D-VSP) in orthognathic surgery: Advantages, disadvantages and pitfalls.

In this article, the advantages, disadvantages and pitfalls of three-dimensional virtual surgical planning (3D-VSP) compared to traditional two-dimensional (2D) planning methods in orthognathic surgery are discussed, alongside a standardised protocol that can be utilised. A skeletal Class II, skeletal Class III and an anterior open bite clinical case along with their 3D-VSP management are presented, highlighting modifications that can be made to computer-aided design/computer-aided manufacture (CAD/CAM) cutting guide and plate designs.

Mandibular shape prediction using cephalometric analysis: applications in craniofacial analysis, forensic anthropology and archaeological reconstruction.

BACKGROUND: The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion. OBJECTIVES: The objectives of this study were to determine whether the Sassouni cephalometric analysis could help predict two-dimensional mandibular shape in humans using cephalometric planes and landmarks. MATERIALS AND METHODS: A retrospective computerised analysis of 100 lateral cephalometric radiographs taken at Kingston Hospital Orthodontic Department was carried out. RESULTS: Results showed that the Euclidean straight-line mean difference between the estimated position of gonion and traced position of gonion was 7.89 mm and the Euclidean straight-line mean difference between the estimated position of pogonion and the traced position of pogonion was 11.15 mm. The length of the anterior cranial base as measured by sella-nasion was positively correlated with the length of the mandibular body gonion-menton, r = 0.381 and regression analysis showed the length of the anterior cranial base sella-nasion could be predictive of the length of the mandibular body gonion-menton by the equation 22.65 + 0.5426x, where x = length of the anterior cranial base (SN). There was a significant association with convex shaped palates and oblique shaped mandibles, p = 0.0004. CONCLUSIONS: The method described in this study can be used to help estimate the position of cephalometric points gonion and pogonion and thereby sagittal mandibular length. This method is more accurate in skeletal class I cases and therefore has potential applications in craniofacial anthropology and the 'missing mandible' problem in forensic and archaeological reconstruction.

Nasolabial angle and nasal tip elevation changes in profile view following a Le Fort I osteotomy with or without the use of an alar base cinch suture: a long-term cohort study.

OBJECTIVES: Cinch sutures attempt to counteract alar base widening but may lead to unintended increases in the nasolabial angle and nasal tip elevation. The aim of this investigation was to assess nasolabial angle changes after maxillary osteotomies with and without alar base cinch sutures in the short and long terms. STUDY DESIGN: Seventy-eight patients were assessed, with 51 in the cinch group (38 females, 13 males; age range 16-39 years) and 27 in the no-cinch group (12 females, 15 males; age range 17-27 years). The upper component (nasal tip elevation), lower component (lower lip inclination), and the overall nasolabial angle were measured on preoperative, postoperative, and long-term follow-up lateral cephalometric radiographs. RESULTS: The overall nasolabial angle (P = .006) and its upper component (P < .001) increased significantly in the cinch group immediately postoperatively but resolved by 6 to 12 months for the overall nasolabial angle and by 12+ months (up to 5.7 years) for the upper component. There were no significant changes in the no-cinch group. CONCLUSIONS: In the short term, the alar base cinch suture increases nasal tip elevation and the overall nasolabial angle. In the long term, there was no significant difference, suggesting that the initial nasal tip elevation resolves over time and that the cinch suture may have a limited effect on nasal tip elevation in the longer term.

Three-dimensional bio-printing and bone tissue engineering: technical innovations and potential applications in maxillofacial reconstructive surgery.

BACKGROUND: Bone grafting has been considered the gold standard for hard tissue reconstructive surgery and is widely used for large mandibular defect reconstruction. However, the midface encompasses delicate structures that are surrounded by a complex bone architecture, which makes bone grafting using traditional methods very challenging. Three-dimensional (3D) bioprinting is a developing technology that is derived from the evolution of additive manufacturing. It enables precise development of a scaffold from different available biomaterials that mimic the shape, size, and dimension of a defect without relying only on the surgeon's skills and capabilities, and subsequently, may enhance surgical outcomes and, in turn, patient satisfaction and quality of life. REVIEW: This review summarizes different biomaterial classes that can be used in 3D bioprinters as bioinks to fabricate bone scaffolds, including polymers, bioceramics, and composites. It also describes the advantages and limitations of the three currently used 3D bioprinting technologies: inkjet bioprinting, micro-extrusion, and laser-assisted bioprinting. CONCLUSIONS: Although 3D bioprinting technology is still in its infancy and requires further development and optimization both in biomaterials and techniques, it offers great promise and potential for facial reconstruction with improved outcome.

The long-term influence of orthodontic treatment on dental knowledge and behaviour: An Australian cohort study.

OBJECTIVES: Fixed orthodontic treatment (FOT) typically lasts 14-33 months, with regular appointments at short intervals to monitor changes, adjust appliances, and remotivate patients to maintain excellent oral hygiene standards to prevent dental disease. Past experiences are important influencers of dental attitudes and self-care dental behaviours in adulthood. Since FOT comprises a high frequency of appointments compared to other dental visiting, we hypothesised that previous FOT enhances dental knowledge and behaviour in later life. METHODS: This cohort study followed-up 30-year-old participants who originally took part in an oral epidemiological study when aged 13-years. Participants completed a questionnaire regarding sociodemographics, dental health behaviours, dental knowledge (prevention of caries and periodontal disease, including questions about popular myths) and FOT. Data analysis comprised un/adjusted binomial logistic regression and multivariate generalised linear regression. RESULTS: Data for 448 participants (56 % female, 35 % received FOT) were analysed; adjusted models controlled for sociodemographics and baseline malocclusion severity. There was no association between FOT and regular toothbrushing (Exp B: 1.35, 95% CI: 0.87-2.10), flossing (Exp B: 1.18, 95 % CI: 0.48-2.90), dental attendance within last 2 years (Exp B: 0.96, 95 % CI: 0.62-1.49) or a non-emergency dental visit (Exp B: 1.01, 95 % CI: 0.51-1.99). Non-FOT participants placed importance on a calcium-rich diet preventing caries (Exp B: 1.99, 95 % CI: 1.14-3.50, P < 0.05), while those with a baseline definite malocclusion had higher levels of knowledge about dental visiting compared to those with minimal or more severe malocclusions (P < 0.05). CONCLUSION: Previous FOT appears to have limited impact on dental knowledge and may not affect long-term dental behaviours. CLINICAL SIGNIFICANCE: This 17-year follow-up study examined the influence of previous fixed orthodontic treatment on dental knowledge and behaviour later in life. Although patients have numerous and regular appointments during the course of orthodontic treatment, this does not seem to impact on either dental knowledge or behaviour in adulthood.