The effects of computer-aided anteroposterior maxillary incisor movement on ratings of facial attractiveness.

BACKGROUND: Before planning orthodontic treatment, it is necessary to understand societal preferences for facial esthetics. The anteroposterior (AP) position of the maxillary incisors affects the appearance of the soft tissue profile and can be manipulated by orthodontic techniques. To improve the ability to predict the most suitable maxillary incisor position, numerous cephalometric and profilometric measurements have been suggested. Among them are the Six Elements to Orofacial Harmony proposed by L. F. Andrews, whereby forehead angulation is used to dictate maxillary incisor sagittal position. Our aim was to evaluate differences in preference for the AP position of the maxillary incisor between orthodontic and lay panels. METHODS: A smiling profile photograph was taken of a female subject who best fit the chosen soft tissue normative values and whose maxillary incisors were in an Element II position. The photograph was manipulated to simulate maxillary protrusion and retrusion at 1-mm increments to a maximum of +/-4 mm. Panels of orthodontists and nonorthodontists scored the attractiveness of the photographic variations according to a 100-mm visual analogue scale. RESULTS: The 4-mm retrusive photograph was significantly less desirable than all others, which suggests that, from an esthetic standpoint, it is preferable to either leave a normally protrusive maxillary dentition where it is or advance rather than retract the maxillary anterior teeth. Orthodontic training did not significantly affect the magnitude of the ratings or pattern of preference in our sample. CONCLUSIONS: Andrews' Element II provides an additional useful method to evaluate attractiveness relative to the maxillary incisor position.     

A longitudinal study of the survival of All-on-4 implants in the mandible with up to 10 years of follow-up

BackgroundImmediate-function implants have become an accepted alternative for fixed restoration protocols in edentulous mandibles on the basis of documented high success rates. The All-on-4 concept (Nobel Biocare, Göteborg, Sweden), a surgical and prosthetic protocol for immediate function involving the use of four implants to support a fixed prosthesis in patients with completely edentulous mandibles, represents one of these protocols. The authors conducted a study to document long-term follow-up of the All-on-4 concept.MethodsThis longitudinal study included 245 patients with a total of 980 immediate-function implants (four per patient), all placed in the anterior region, to support fixed full-arch mandibular prostheses. The inclusion criterion was having an edentulous mandible, or a mandible with hopeless teeth, in need of fixed implant restorations.ResultsA total of 21 implants failed in 13 patients, giving cumulative patient-related and implant-related success rates of 94.8 percent and 98.1 percent, respectively, at five years, and 93.8 percent and 94.8 percent, respectively, with up to 10 years of follow-up. The prostheses’ survival rate was 99.2 percent with up to 10 years of follow up.ConclusionsThe results support the conclusion that use of the All-on-4 immediate-function implant concept in completely edentulous mandibles is viable in the long term.Clinical ImplicationsHigh prosthesis survival rates can be achieved by the use of four implants to support a full-arch fixed prosthesis in the mandible.     

The effect of core:dentin thickness ratio on the bi-axial flexure strength and fracture mode and origin of bilayered dental ceramic composites.

OBJECTIVES: The aim of the current study was to assess the effect of core:dentin thickness ratio on the flexure strength, fracture mode and origin of bilayered dental ceramic composite disc specimens. METHODS: Sets of 30 bilayered composite discs with core:dentin thickness ratio of 2:1, 1:1 and 1:2 were tested in bi-axial flexure with both the reinforcing core and veneering dentin loaded in tension. Mean flexure strengths, standard deviations and associated Weibull Moduli (m) were determined. A combination of optical and scanning electron microscopy was employed for identification of the fracture mode and origin. RESULTS: The core:dentin ratio influenced the bi-axial flexure strength and reliability of the flexure strength data when both the reinforcing core and veneering dentin porcelain were tested in tension. The strength and reliability was increased for a core:dentin thickness of 2:1. The number of fracture fragments, the frequency of occurrence of specimen delaminations, Hertzian cone formations and sub-critical radial cracking in the bilayered dental ceramic composite disc shaped specimens was also dependent on the core/dentin ratio and the surface loaded in tension. CONCLUSIONS: Core:dentin thickness ratio influences the bi-axial flexure strength and fracture mode and origin in bilayered dental ceramic composite specimens.     

Today's threat is tomorrow's crisis: advocating for dental education, dental and biomedical research, and oral health

The current political environment in the nation's capital threatens federal support for programs vital to the academic dental community. To develop a strong cadre of advocates who can deliver an effective and unified message to members of Congress on behalf of dental education and dental research, the American Dental Education Association (ADEA) and the American Association for Dental Research (AADR) created a new organizational structure: the National Oral Health Advocacy Committee (NOHAC) and the National Advocacy Network (NAN). The basic skills and knowledge required to function as an effective advocate include an understanding of the political environment, a working knowledge of the legislative processes and the political players, and the ability to build and work with grassroots networks and coalitions. NOHAC and NAN are designed to provide leadership in these areas to support effective advocacy for dental education and dental research.     

Prevalence of missing posterior teeth and intraarticular temporomandibular disorders.

STATEMENT OF PROBLEM: The association between missing mandibular posterior teeth and the development of intraarticular temporomandibular disorders (TMDs) remains unclear. PURPOSE: The purpose of this study was to evaluate the prevalence of missing mandibular posterior teeth and intraarticular TMDs in a mixed population of asymptomatic subjects and symptomatic TMD patients. MATERIAL AND METHODS: Eighty-two asymptomatic volunteers and 263 symptomatic TMD patients were included in this study. Asymptomatic volunteers completed a subjective questionnaire and underwent clinical examination to document the absence of TMD signs and symptoms. All symptomatic subjects had localized jaw joint pain and pain on movement or when eating. The number of missing mandibular bicuspid and molar teeth (excluding third molars) in each subject was recorded, and magnetic resonance images were made to document the presence or absence of disk displacement in the temporomandibular joints. Subjects were divided into 4 groups: group 1 = asymptomatic, normal magnetic resonance imaging result; group 2 = asymptomatic, disk displacement; group 3 = symptomatic, normal magnetic resonance imaging result; and group 4 = symptomatic, disk displacement. Collected data were analyzed with chi-square tests (P<.05) with no adjustment for multiple comparisons. RESULTS: A positive association between missing mandibular posterior teeth and the presence of disk displacement was found. CONCLUSION: The literature does not suggest that replacement of missing posterior teeth prevents the development of TMDs. However, missing mandibular posterior teeth may accelerate the development of degenerative joint disease.     

Comparison of skeletal and dental morphology in asymptomatic volunteers and symptomatic patients with unilateral disk displacement with reduction

The purpose of this study was to evaluate the effect of unilateral disk displacement with reduction (UDDR) on the skeletal and dental pattern of affected individuals. There were 18 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. Analysis of variance was used to compare the symptomatic with the control subjects. A few skeletal differences were found. There was an overall reduction in length of the anterior (S-Na) and posterior (S-Ba) cranial base measurements in the UDDR group. The cranial base angle was also increased. Both upper and lower dentures bases were retropositioned. The posterior ramal height (Ar-Go) was shorter in the symptomatic group. This study showed that alterations in skeletal morphology may be associated with UDDR. The mechanisms that produce DD or the mechanisms that cause this skeletal alteration are yet to be clarified. This study suggests that subjects with UDDR may manifest altered craniofacial morphology. The clinician should be aware of this possibility, especially for growing patients.     

Comparison of skeletal and dental morphology in asymptomatic volunteers and symptomatic patients with bilateral disk displacement without reduction

The purpose of this study was to evaluate the effect of bilateral disk displacement without reduction (BDDN) on the skeletal and dental pattern of affected individuals. There were 59 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance imaging scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. A smaller cranial base length (Ba-Na) was found in the symptomatic group. The facial plane angle was smaller, and the angle of convexity was larger because of the retropositioned mandible. The lower denture base was also retruded as shown by the smaller SNB angle. The BDDN group exhibited a larger overjet. The mandibular plane angle was steeper, the Y-axis was more vertical (S-Gn to FH), the posterior ramal height (Ar-Go) was shorter, and the angle between the mandibular and the palatal plane (PP to MP angle) was increased in the symptomatic group. No significant dental differences were found. This study showed that alterations in skeletal morphology might be associated with BDDN. This study suggests that subjects with BDDN may manifest altered craniofacial morphology. The clinician should be aware of that possibility, especially for the growing patients and the surgical candidates.     

Consensus statement on fiber-reinforced polymers: current status,future directions,and how they can be used to enhance dental care

The Second Scientific Fibre Reinforcement Symposium was held in Nijmegen, The Netherlands, on October 13th, 2001. The participants were invited speakers with extensive scientific and clinical backgrounds in glass fiber and polyethylene fiber research. The symposium reports focused on four areas of fiber reinforcement research: materials development, laboratory testing, clinical systems development, and clinical data. The consensus reached on the current status and future directions of this technology is reported here.     

Sleep disturbances in 22q11.2 deletion syndrome: a case with obstructive and central sleep apnea.

The 22q11.2 deletion syndrome is characterized by wide phenotypic variability, frequently involving characteristic craniofacial features, cardiac malformations, and learning difficulties. Skeletal anomalies are also common and include an obtuse angle of the cranial base, retrognathia, and cervical spine abnormalities. Despite these anomalies, sleep-disturbed breathing is not reported frequently in patients with 22q11.2 deletion syndrome. We describe a patient with an obstructive sleep disturbance that was successfully treated with a tonsillectomy followed by mandibular distraction osteogenesis. She also had central sleep apnea, initially attributed to spinal cord impingement from cervical instability. Posterior cervical fusion was associated with a decrease in the number of central apneic events.