Noncontact intraoral measurement of force-related tooth mobility.

The aim of this pilot study was to measure force-related tooth mobility. Vertical and horizontal anterior tooth mobility in 31 healthy periodontal subjects was measured by a noncontact optical measurement technique. The subjects continuously increased the force on each tooth by biting on a load cell. An automated software program recorded tooth displacement at 9-N intervals. Vertical and horizontal displacements were subsequently measured. The vector of tooth mobility in the buccal direction was calculated using the Pythagorean theorem. The average displacements over all subjects for each tooth were determined. Global differences were assessed with the Wilcoxon test. There were no significant differences between contralateral teeth overall load stages. There were no significant differences in tooth mobility between the central and lateral incisors except for in the horizontal direction. However, there were significant differences between central incisor and canine and lateral incisor and canine teeth.

Prosthetic considerations for orthodontic implant site development in the adult patient.

Proper site development is a key factor for long-term clinical success of dental implants. Whereas surgical and restorative techniques have been refined to ensure predictable functional and esthetic outcome, individual clinical prerequisites do not always allow proper placement of implants when prosthetic and material properties are considered. Orthodontic tooth movement may be a viable and nonsurgical site development treatment option. With the introduction and advancements of minimal invasive and less visible orthodontic appliances, a growing number of adult patients are willing to obtain orthodontic treatment. The spectrum of modern appliances is broad and ranges from clear aligners to lingual brackets. Skeletal anchorage devices such as orthodontic mini-implants often eliminate unpopular external anchorage devices (ie, headgear) in adult patients, This article discusses the selection of an appropriate pretreatment approach by taking patient-specific criteria into account.

Biomechanical methods applied in dentistry: a comparative overview of photoelastic examinations, strain gauge measurements, finite element analysis and three-dimensional deformation analysis.

The aim of this article is to illustrate and discuss current methods applied in the analysis of biomechanical components in dental applications. For illustration purposes, the strain development of a non-passively fitting implant supported fixed restoration was evaluated using the four techniques: photoelastic examination, strain gauge measurements, finite element analysis, and three-dimensional deformation analysis. Photoelastic analysis only allowed for a raw estimation of the strains evoked by superstructure fixation. Quantitative results could be derived from both strain gauge measurements and three-dimensional deformation analysis which could then be used to simulate the loading situation around the supporting implants.

The effect of provisional restoration type on micromovement of implants.

STATEMENT OF PROBLEM: The osseointegration or fibrous encapsulation of immediately loaded dental implants depends largely on the extent of implant micromovement. The impact of acrylic resin or metal-reinforced acrylic resin provisional restorations on this movement is currently unknown. PURPOSE: The purpose of this study was to isolate and measure the effect of provisional restoration type on the vertical displacement of adjacent implants under load at 2 locations. MATERIAL AND METHODS: Vertical loads ranging from 10-200 N were applied to polymethyl methacrylate resin (n=56) or metal-reinforced acrylic resin provisional restorations (n=56) supported by 4 implants inserted into homogenous artificial bone in a "u-shaped" alignment. Provisional restorations were first loaded in the anterior segment where the provisional restoration was supported by a mesial and distal implant, followed by loading on an extension 8 mm distal to the last implant. Vertical displacement of the 2 implants nearest the load application was measured and recorded using an optical image correlation technique based on photogrammetric principles. Data were subjected to a nonparametric multivariate analysis (generalized Wilcoxon test) and a Mann-Whitney test with a 2-tailed P value (alpha=.05). RESULTS: There was no significant difference in the vertical implant displacement of the 2 provisional restoration groups when they were loaded in the anterior segment. However, when loads were applied to the distal cantilever, metal reinforcement resulted in less vertical displacement of the next-to-last implant. The mean vertical displacement of the next-to-last implant when supporting an acrylic resin provisional restoration increased from 20 microm +/-3 microm (pooled loads of 10-50 N) to 130 microm +/-21 microm (pooled loads of 160-200 N), while the vertical displacement of the implant when retaining a metal-reinforced acrylic resin provisional restoration increased from 10 microm +/-2 microm to 69 microm +/-13 microm under the same loads (P

Three-dimensional analysis of facial symmetry in cleft lip and palate patients using optical surface data.

AIM: Presentation of a new technique to determine the plane of symmetry of a face, and to assess the degree of facial symmetry in patients with unilateral cleft lip and palate based on three-dimensional (3D) optical surface data. PATIENTS AND METHODS: After having determined a plane of symmetry according to optical 3D facial surface data, we identified differences in landmarks, the surface areas of the upper lip vermilion and nostrils and virtual volumes of the midface, nose and upper lip for cleft and unaffected sides in forty 10-year-old patients suffering from complete unilateral cleft lip, alveolus and palate. The children had undergone lip repair via the Tennison-Randall technique and had received subsequent orthodontic treatment (but not secondary osteoplasty). RESULTS: Statistically significant differences were apparent between cleft and non-cleft sides in terms of the nasal landmarks, nostril angle and virtual volume of the nose. The upper lip was symmetrical when cleft and non-cleft sides were compared. CONCLUSIONS: This new technique of symmetry analysis reveals that the noses of 10-year-old patients with complete unilateral cleft lip and palate who had not undergone revisional surgery present a measurable and significant degree of asymmetry, while the upper lip is symmetrical as a consequence of interdisciplinary treatment by orthodontists and oral and maxillofacial surgeons. Further 3D analyses on larger numbers of patients will allow more comprehensive and consistent analysis of the potential and limitations of various surgical and conservative methods so as to identify those techniques with the best outcome in terms of facial symmetry.

[Psychological and dental considerations in the prosthetic rehabilitation of children. Child prothesis--part I]. / Psychologische und zahnmedizinische Aspekte bei der prothetischen Versorgung von Kindern. Kinderprothesen--Teil I.

The fabrication of a prosthesis for a child requires an extensive diagnostic process together with a detailed medical and dental history. The treatment modalities for children and adults are different. By young patients attention must be paid in order to establish a feeling of trust and close cooperation between the dentist and the patient. The aim of the treatment with removable denture prosthesis is the re-establishment of aesthetic, phonetic and function while assuring at the same time a high standard of oral hygiene and periodontal maintenance. The continuous jaw growth and the dentition changes of a child must be closely monitored. Therefore, frequent (3-6 months recall intervals) follow-up examinations and denture adjustments are needed.

[Technical treatment considerations in making prostheses for children. Child prostheses--Part 2]. / Behandlungstechnische Aspekte bei der Anfertigung von Kinderprothesen. Kinderprothesen--Teil II.

The rehabilitation of a child's dentition with a removable prosthesis is more complex and time consuming, when comparing it to the one of adults. Prerequisite for a successful treatment is a careful consideration of age-related, technical, functional and psychological aspects. The aesthetic and functional replacement of the missing teeth using a removable prosthesis results in an increased self-esteem for the young patients. This case report describes the management of a young child as well as the treatment planning and the prosthetic rehabilitation process.

Retrieval analysis of different orthodontic brackets: the applicability of electron microprobe techniques for determining material heterogeneities and corrosive potential.

OBJECTIVE: The objective of this study was to investigate the applicability of micro-analytical methods with high spatial resolution to the characterization of the composition and corrosion behavior of two bracket systems. MATERIAL AND METHODS: The surfaces of six nickel-free brackets and six nickel-containing brackets were examined for signs of corrosion and qualitative surface analysis using an electron probe microanalyzer (EPMA), prior to bonding to patient's tooth surfaces and four months after clinical use. The surfaces were characterized qualitatively by secondary electron (SE) images and back scattered electron (BSE) images in both compositional and topographical mode. Qualitative and quantitative wavelength-dispersive analyses were performed for different elements, and by utilizing qualitative analysis the relative concentration of selected elements was mapped two-dimensionally. The absolute concentration of the elements was determined in specially prepared brackets by quantitative analysis using pure element standards for calibration and calculating correction-factors (ZAF). RESULTS: Clear differences were observed between the different bracket types. The nickel-containing stainless steel brackets consist of two separate pieces joined by a brazing alloy. Compositional analysis revealed two different alloy compositions, and reaction zones on both sides of the brazing alloy. The nickel-free bracket was a single piece with only slight variation in element concentration, but had a significantly rougher surface. After clinical use, no corrosive phenomena were detectable with the methods applied. Traces of intraoral wear at the contact areas between the bracket slot and the arch wire were verified. CONCLUSION: Electron probe microanalysis is a valuable tool for the characterization of element distribution and quantitative analysis for corrosion studies.

Pilot study on accuracy and dimensional stability of impression materials using industrial CT technology.

OBJECTIVE: Using computed tomography, scan impressions can be saved and edited as virtual data. The aim of this study was to evaluate the parameters influencing different impression materials and impression trays and their relevance with regard to accuracy and dimensional stability. MATERIALS AND METHODS: Two alginate impressions (Zhermack Hydrogum®5 and Kaniedenta Tetrachrom®) and a polyether impression (3MEspe Impregum™) were each combined with two acrylic trays (3M Espe Position Tray™ and Profimed Opti-Tray) and CT scanned immediately after impression at the Fraunhofer Institute Development Center for X-ray Technology (EZRT) in Fürth, Germany. Each impression was digitized 10 times on the same day, 3 times after 2 days and twice after 6 days, thus determining the dimensional stability of the various materials. An acrylic model was digitized with a high-resolution µCT research scanner to be used as a reference for assessing the accuracy of the impression materials. For graphic and statistical analysis, VGStudio Max® was used. RESULTS: Both alginate impressions were less dimensionally stable than the polyether impression material. The Zhermack Hydrogum®5 alginate impression resulted in more deviation (151 µm) after 6 days than the Kaniedenta Tetrachrom® impression. The polyether scans showed a mean deviation of 73 µm. The accuracy of both alginates was similarly precise (mean value: Hydrogum®5 0.129 ± 0.021 mm, Tetrachrom® 0.137 ± 0.002 mm). The type of tray had limited influence on the results of the alginate impressions, while the accuracy of the Impregum™ impression depended on the tray combination chosen. CONCLUSION: The accuracy of the alginate impressions is sufficient for clinical use in orthodontics and produced, with correct storage, acceptable results even after 2 days. Hydrogum®5 impressions proved to be slightly more accurate than the reference material but less dimensionally stable than the Tetrachrom® impressions. The 3M Espe Position Tray™ seemed to be more practical due to a better retentive effect compared to the Opti-Tray made by Profimed.

Quantitative assessment of orthodontic mini-implant displacement: the effect of initial force application.

OBJECTIVE: Primary stability and micromovement of orthodontic mini-implants depends on a number of factors and influences clinical success or failure. The purpose of this study was to assess the behavior of orthodontic mini-implants upon initial load application. METHOD AND MATERIALS: Orthodontic mini-implants (n = 39) were inserted in the alveolar process of maxillary human cadaver specimens (n = 10). Increasing horizontal forces (up to 2.5 N) were applied, and triggered images were taken in 0.5-N load intervals. Additionally, peri-implant parameters based on micro-CT volume data were recorded. Data were subjected to a two-sided nonparametric Wilcoxon signed rank test, and between-group comparisons were assessed with a Mann-Whitney test (alpha = .05). RESULTS: Initial load application led to displacement beyond elastic recovery of the surrounding bone after force release (P < .001). Cortical thickness and insertion depth, despite numeric differences, did not reveal any statistical differences, while displacement of mini-implants was significantly affected by contact to neighboring teeth (P < .001). CONCLUSIONS: Insertion technique and initial load application on orthodontic mini-implants may be regarded as two crucial factors for success, while repeated application of orthodontic force does not seem to increase screw mobility.

Dental aspects in patients with DiGeorge syndrome.

DiGeorge syndrome, which is caused by a microdeletion of 1.5 to 3.0 megabases on the long arm of chromosome 22, has an incidence of approximately 1:4,000 to 1:5,000 live births. The phenotypic spectrum of this disorder includes congenital heart defects, immunodeficiency due to thymic hypoplasia or aplasia, transient or permanent hypocalcemia due to parathyroid hypoplasia or aplasia, developmental retardation, and psychiatric disorders. Dental aspects in these patients include skeletal malformations, velopharyngeal insufficiency with or without cleft palate, small mouth, and hypotonus orofacial musculature, as well as impaired salivary flow. Enamel aberrations related to hypocalcemia may result in a higher frequency of dental caries. Based on a series of five patients, the medical and dental aspects that have to be considered in the care of patients with DiGeorge syndrome are presented.

Diagnostic potential of 3D-data-based reconstruction software: an analysis of the rare disease pattern of cherubism.

Cherubism is an autosomal-dominant syndrome characterized by bilateral maxillomandibular bony degeneration, fibrous connective tissue hyperplasia, and displacement of permanent tooth germs. Reossification of the cystic lumen occurs spontaneously, but dislocated teeth must be realigned orthodontically. Advancements in virtual 3D reconstruction of anatomic structures based on computed tomography (CT) or cone beam CT data have provided for more predictable individual treatment planning. We evaluated two software programs for making densitometry and volume measurements of cystic areas in the mandibles, and for 3D visualization of permanent tooth germs within the cystic lumen, in two siblings with cherubism.

Vertical and sagittal growth in patients with unilateral and bilateral cleft lip and palate-a retrospective cephalometric evaluation.

OBJECTIVE: To investigate whether the craniofacial vertical and sagittal jaw relationship in patients with cleft lip and palate (CLP) differed from that of age-matched noncleft controls, before and after the pubertal growth spurt. DESIGN: Retrospective observational study. PATIENTS: The study group comprised 126 patients with CLP, subdivided according to gender and cleft type, and the control group comprised 53 age-matched skeletal class I patients. METHODS: Angular and linear measurements were taken from prepubertal and postpubertal lateral cephalograms of all patients. RESULTS: In patients with cleft lip and palate, the maxillary retrognathism became more remarkable with increasing age; whereas, the retrognathic position of the mandible became less pronounced as compared with controls. Reduced posterior midfacial height, a common prepubertal finding in patients with cleft lip and palate, was significant in postpubertal girls and young women with unilateral cleft lip and palate (p = .002). The total anterior facial height in male patients with bilateral cleft lip and palate was larger than in control patients (p = .002) after the pubertal growth spurt due to an increased anterior midfacial height. In male patients with unilateral cleft lip and palate, this finding was due to an increased anterior lower facial height (p < .001). CONCLUSIONS: Patients with cleft lip and palate treated according to a standardized treatment concept had adequate craniofacial jaw relationships after puberty. Despite a measured skeletal class I in both male and female patients with cleft lip and palate regardless of cleft type, there was a slight tendency toward a skeletal class III. Findings were similar for all groups of cleft lip and palate patients irrespective of the type of orthodontic treatment performed.

Blood transfusion in bimaxillary orthognathic operations: need for testing of type and screen.

We prospectively evaluated the incidence of blood transfusion in 105 consecutively treated patients (45 men and 60 women) having bimaxillary orthognathic operations, to find out whether type and screen testing are adequate in clinical practice. All patients had Le Fort I osteotomy combined with bilateral sagittal split osteotomy of the ramus. The preoperative routine was restricted to type and screen testing and verification of ABO/Rhesus (Rh) status. Autologous blood donation or routine cross-matching of allogeneic units of blood was not done. Intraoperative haemoglobin concentrations and the need for blood transfusion in patients having bimaxillary osteotomies were recorded in a prospective database. The mean duration of operation was 196 min (range 115-325). The median length of hospital stay was 8 days (range 4-16). The mean (SD) reduction in haemoglobin during operation was 34 (16)g/L in men and 32 (10)g/L in women (p=0.32). No patients had an allogeneic blood transfusion. We found that type and screen testing and verification of ABO/Rh status seems to be an adequate precaution to manage blood loss. As reflected by the low rate of transfusion in the present study, severe haemorrhage that requires transfusion of allogeneic blood has become the exception rather than the rule in bimaxillary orthognathic operations.

Updated implant-retained restorative solutions in patients with hypodontia.

Hypodontia is often found during orthodontic screening and occurs with a prevalence of between 5% and 10%. One or more congenitally missing permanent teeth is a clinical finding that affects both male and female patients. Although maintaining deciduous teeth is an option in a few cases, the majority of patients with agenesis of teeth require extraction and orthodontic space closure or restorative treatment. Depending on the number and location of missing teeth, implant-supported fixed single-tooth restorations provide excellent long-term results. Choosing appropriate treatment techniques and materials will result in long-term clinical function, stability, and esthetic success.

Three-dimensional analysis of changes of the malar-midfacial region after LeFort I osteotomy and maxillary advancement.

AIM: It has been the objective of the present prospective study to assess visible volume changes of the facial soft tissue after LeFort I osteotomy with advancement and to determine the soft-tissue-to-hard-tissue ratios of advancement. PATIENTS AND METHODS: Twenty adult patients (ten female, ten male, mean age 33.9 +/- 14.9 years) received a LeFort I osteotomy with advancement because of a maxillary protrusion. Lateral skull radiographs and optical three-dimensional (3D) scans of the facial surface were assessed preoperatively and 12 months after surgery. The lateral skull radiographs were used to carry out standard linear and angular cephalometric measurements. The pre- and postoperative optical 3D surface scans were registered. A well-defined area in the malar region was used to determine the visible volume changes for each side separately. The mean accommodation vector that transforms the preoperative into the postoperative surface was assessed for each facial half separately. The soft-tissue-to-hard-tissue ratios between the incision superius and the labrale superius, the maximal parasagittal advancement of soft tissue, and the accommodation vectors were calculated. RESULTS: A mean advancement of the incision superius of 5.3 +/- 2.1 mm was accompanied by a volume increase of 5.2 +/- 4.1 cm(3) in the right malar-midfacial region and 4.6 +/- 4.7 cm(3) on the left side, respectively, revealing a symmetrical volume change (p = 0.370). The soft-tissue-to-hard-tissue ratios were 80 +/- 94% for labrale superius and incision superius, 56 +/- 79% (right) and 51 +/- 56% (left) for accommodation vector and incision superius and 97 +/- 79% (right) and 98 +/- 89% (left) for maximal parasagittal advancement of soft tissue and incision superius. DISCUSSION: The determination of volume changes and accompanying accommodation vectors complete the cephalometric analysis during the follow-up of patients undergoing LeFort I osteotomy. The data show that maxillary advancement leads to a more pronounced shifting of the soft tissues in the malar-midfacial area than of the upper lip. The new parameters will help to assess normative soft tissue data based on 3D imaging with a view to an improved three-dimensional prediction of the operative outcome of orthognathic surgery away from the midline.

Retrieval analysis of different orthodontic brackets: the applicability of electron microprobe techniques for determining material heterogeneities and corrosive potential

OBJECTIVE: The objective of this study was to investigate the applicability of micro-analytical methods with high spatial resolution to the characterization of the composition and corrosion behavior of two bracket systems. MATERIAL AND METHODS: The surfaces of six nickel-free brackets and six nickel-containing brackets were examined for signs of corrosion and qualitative surface analysis using an electron probe microanalyzer (EPMA), prior to bonding to patient's tooth surfaces and four months after clinical use. The surfaces were characterized qualitatively by secondary electron (SE) images and back scattered electron (BSE) images in both compositional and topographical mode. Qualitative and quantitative wavelength-dispersive analyses were performed for different elements, and by utilizing qualitative analysis the relative concentration of selected elements was mapped two-dimensionally. The absolute concentration of the elements was determined in specially prepared brackets by quantitative analysis using pure element standards for calibration and calculating correction-factors (ZAF). RESULTS: Clear differences were observed between the different bracket types. The nickel-containing stainless steel brackets consist of two separate pieces joined by a brazing alloy. Compositional analysis revealed two different alloy compositions, and reaction zones on both sides of the brazing alloy. The nickel-free bracket was a single piece with only slight variation in element concentration, but had a significantly rougher surface. After clinical use, no corrosive phenomena were detectable with the methods applied. Traces of intraoral wear at the contact areas between the bracket slot and the arch wire were verified. CONCLUSION: Electron probe microanalysis is a valuable tool for the characterization of element distribution and quantitative analysis for corrosion studies.

Restoration of a nonrestorable central incisor using forced orthodontic eruption, immediate implant placement, and an all-ceramic restoration: a clinical report.

The long-term clinical and esthetic success of an implant-supported restoration is determined by stable periimplant soft-tissue morphology that is in harmony with the surrounding tissue architecture of the natural dentition. An interdisciplinary approach can significantly improve predictability when restoring missing teeth in the anterior maxilla. This clinical report describes the application of forced orthodontic eruption prior to initiation of surgical and restorative implant treatment to achieve a coronal shift of bone and gingiva and enhance the 3-dimensional topography of the recipient implant site.