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1.  Effects of sleep bruxism on functional and occlusal parameters: a prospective controlled investigation 
This study was conducted to verify the results of a preceding retrospective pilot study by means of a prospective controlled investigation including a larger sample size. Therefore, the aim of this clinical investigation was to analyze the relationship between sleep bruxism and several functional and occlusal parameters. The null hypothesis of this study was that there would be no differences among sleep bruxism subjects and non-sleep bruxism controls regarding several functional and occlusal parameters. Fifty-eight sleep bruxism subjects and 31 controls participated in this study. The diagnosis sleep bruxism was based on clinical criteria of the American Academy of Sleep Medicine. Sixteen functional and occlusal parameters were recorded clinically or from dental study casts. Similar to the recently published retrospective pilot study, with a mean slide of 0.77 mm (s.d., 0.69 mm) in the sleep bruxism group and a mean slide of 0.4 mm (s.d., 0.57 mm) in the control group, the evaluation of the mean comparison between the two groups demonstrated a larger slide from centric occlusion to maximum intercuspation in sleep bruxism subjects (Mann–Whitney U-test; P=0.008). However, following Bonferroni adjustment, none of the 16 occlusal and functional variables differed significantly between the sleep bruxism subjects and the non-sleep bruxism controls. The present study shows that the occlusal and functional parameters evaluated do not differ between sleep bruxism subjects and non-sleep bruxism subjects. However, as the literature reveals a possible association between bruxism and certain subgroups of temporomandibular disorders, it appears advisable to incorporate the individual adaptive capacity of the stomatognathic system into future investigations.
doi:10.1038/ijos.2012.48
PMCID: PMC3464987  PMID: 22935746
dental occlusion; functional parameters; prospective study; sleep bruxism
2.  Correlation between stress, stress-coping and current sleep bruxism 
Background
Stress is discussed as a potential factor in the development of sleep bruxism (SB). The aim of this study was to investigate whether specific stress-factors correlate with SB-activity.
Methods
Sixty-nine subjects, of which 48 were SB-patients, completed three German questionnaires assessing different stress-parameters and stress-coping-strategies: Short questionnaire for recognition of stress-factors (Kurzer Fragebogen zur Erfassung von Belastungen, KFB), Questionnaire for recuperation and strain (Erholungs-Belastungs-Fragebogen, EBF-24 A/3) and the stress-coping questionnaire (Stressverarbeitungsfragebogen-78, SVF-78). The diagnosis of SB was based on the clinical criteria of the American Academy of Sleep Medicine (AASM). The degree of SB-activity was measured by the Bruxcore-Bruxism-Monitoring-Device (BBMD, Bruxcore, Boston, USA), worn for five consecutive nights and analyzed using a computer-based method. Non-parametric Spearman correlation coefficients, rho, were calculated between the psychometric data and the amount of SB-activity measured by a pixel score of the BBMD.
Results
Significant correlations were found for 'daily problems' (r = 0.461, p < 0.01), 'trouble at work' (r = 0.293), 'fatigue' (r = 0.288), 'physical problems' (r = 0.288) and the coping-strategy 'escape' (r = 0.295) (all p < 0.05).
Conclusions
Within the limitations of this study it could be shown that subjects with high SB-activity tend to feel more stressed at work and in their daily life, which in turn might influence their physical state. These subjects also seem to deal with stress in a negative way. However, due to the rather low to almost moderate correlation coefficients and the descriptive character of the study, further investigations are necessary to examine a possible causal relationship.
doi:10.1186/1746-160X-6-2
PMCID: PMC2841116  PMID: 20205705
3.  A histomorphometric meta-analysis of sinus elevation with various grafting materials 
Head & Face Medicine  2009;5:12.
Several grafting materials have been used in sinus augmentation procedures including autogenous bone, demineralized freeze-dried bone (DFDBA), hydroxyapatite, β-tricalcium phosphate (β-TCP), anorganic deproteinized bovine bone and combination of these and others. Up to now a subject of controversy in maxillofacial surgery and dentistry is, what is the most appropriate graft material for sinus floor augmentation.
The aim of this study is to provide a body of evidence-based data regarding grafting materials in external sinus floor elevation concerning the fate of the augmented material at the histomorphological level, through a meta-analysis of the available literature.
The literature searches were performed using the National Library of Medicine. The search covered all English and German literature from 1995 until 2006. For analyzing the amount of bone the parameter "Total Bone Volume" (TBV) was assessed. TBV is determined as the percentage of the section consisting of bone tissue.
In a relatively early phase after implantation the autogenous bone shows the highest TBV values. Interestingly, the different TBV levels approximate during the time. After 9 months no statistically significant differences can be detected between the various grafting materials.
From a clinical point of view, the use of autogenous bone is advantageous if a prosthetic rehabilitation (with functional loading) is expected within 9 months. In other cases the use of anorganic deproteinized bovine bone in combination with autogenous bone seems to be preferable. Donor side morbidity is ignored in this conclusion.
doi:10.1186/1746-160X-5-12
PMCID: PMC2700082  PMID: 19519903
4.  Osseointegration of zirconia implants compared with titanium: an in vivo study 
Head & Face Medicine  2008;4:30.
Background
Titanium and titanium alloys are widely used for fabrication of dental implants. Since the material composition and the surface topography of a biomaterial play a fundamental role in osseointegration, various chemical and physical surface modifications have been developed to improve osseous healing. Zirconia-based implants were introduced into dental implantology as an altenative to titanium implants. Zirconia seems to be a suitable implant material because of its tooth-like colour, its mechanical properties and its biocompatibility. As the osseointegration of zirconia implants has not been extensively investigated, the aim of this study was to compare the osseous healing of zirconia implants with titanium implants which have a roughened surface but otherwise similar implant geometries.
Methods
Forty-eight zirconia and titanium implants were introduced into the tibia of 12 minipigs. After 1, 4 or 12 weeks, animals were sacrificed and specimens containing the implants were examined in terms of histological and ultrastructural techniques.
Results
Histological results showed direct bone contact on the zirconia and titanium surfaces. Bone implant contact as measured by histomorphometry was slightly better on titanium than on zirconia surfaces. However, a statistically significant difference between the two groups was not observed.
Conclusion
The results demonstrated that zirconia implants with modified surfaces result in an osseointegration which is comparable with that of titanium implants.
doi:10.1186/1746-160X-4-30
PMCID: PMC2614983  PMID: 19077228
5.  Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces 
Head & Face Medicine  2008;4:29.
Background
Osseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility make zirconia a suitable material for dental implants, although surface processings are still problematic. The aim of the present study was to compare osteoblast behavior on structured zirconia and titanium surfaces under standardized conditions.
Methods
The surface characteristics were determined by scanning electron microscopy (SEM). In primary bovine osteoblasts attachment kinetics, proliferation rate and synthesis of bone-associated proteins were tested on different surfaces.
Results
The results demonstrated that the proliferation rate of cells was significantly higher on zirconia surfaces than on titanium surfaces (p < 0.05; Student's t-test). In contrast, attachment and adhesion strength of the primary cells was significant higher on titanium surfaces (p < 0.05; U test). No significant differences were found in the synthesis of bone-specific proteins. Ultrastructural analysis revealed phenotypic features of osteoblast-like cells on both zirconia and titanium surfaces.
Conclusion
The study demonstrates distinct effects of the surface composition on osteoblasts in culture. Zirconia improves cell proliferation significantly during the first days of culture, but it does not improve attachment and adhesion strength. Both materials do not differ with respect to protein synthesis or ultrastructural appearance of osteoblasts. Zirconium oxide may therefore be a suitable material for dental implants.
doi:10.1186/1746-160X-4-29
PMCID: PMC2614982  PMID: 19063728
6.  Osseointegration of zirconia implants: an SEM observation of the bone-implant interface 
Head & Face Medicine  2008;4:25.
Background
The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level.
Methods
A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface.
Results
Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography.
Conclusion
The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.
doi:10.1186/1746-160X-4-25
PMCID: PMC2583968  PMID: 18990214
7.  The extent of the psychological impairment of prosthodontic outpatients at a German University Hospital 
Head & Face Medicine  2008;4:23.
Background
Psychological factors are not only important in patients with temporomandibular disorders (TMDs), but also in patients suffering from tooth loss and/or in those awaiting prosthodontic care with fixed or removable dentures as several authors emphasize. The purpose of the present prospective observational study was to compare prosthodontic outpatients of the Department of Prosthodontics at the University of Duesseldorf and patients seeking care at the TMD/Orofacial Pain Outpatient Clinic (TMD/OFPOC) at the same university with respect to sociodemographic data, self-reported somatic complaints, and psychological impairment.
Methods
A total of 234 patients received two self-administered questionnaires including the Symptom-Check-List. Complete data have been obtained from 65 prosthodontic outpatients and 60 patients of the TMD/OFPOC.
Results
Results indicated statistically significant group differences regarding sociodemographic data and somatic complaints. Concerning the latter, in 11 of the 21 items, groups differed significantly and confirmed the absence of any mixing between the two outpatient clinics. Although the evaluation of psychological impairment revealed no significant group differences, in 21.9% of the prosthodontic outpatients and in 22.0% of the patients from the TMD/OFPOC, the extent of the determined psychological impairment was similar to that of psychotherapeutic outpatients; in 9.4% and 8.5% it was similar to that of psychotherapeutic inpatients, respectively.
Conclusion
Within the limitations of this study, in approximately one third of the evaluated patients of both the prosthodontic outpatient clinic and the TMD/OFPOC the psychological impairment reached values comparable to those of psychotherapeutic outpatients and psychotherapeutic inpatients. Therefore, the present findings emphasize the need to intensify the integration of psychosomatic aspects into dentistry and, in particular, to add psychological considerations to future German education plans.
doi:10.1186/1746-160X-4-23
PMCID: PMC2579285  PMID: 18947386
8.  Induction of osteogenic markers in differentially treated cultures of embryonic stem cells 
Head & Face Medicine  2008;4:10.
Background
Facial trauma or tumor surgery in the head and face area often lead to massive destruction of the facial skeleton. Cell-based bone reconstruction therapies promise to offer new therapeutic opportunities for the repair of bone damaged by disease or injury. Currently, embryonic stem cells (ESCs) are discussed to be a potential cell source for bone tissue engineering. The purpose of this study was to investigate various supplements in culture media with respect to the induction of osteogenic differentiation.
Methods
Murine ESCs were cultured in the presence of LIF (leukemia inhibitory factor), DAG (dexamethasone, ascorbic acid and β-glycerophosphate) or bone morphogenetic protein-2 (BMP-2). Microscopical analyses were performed using von Kossa staining, and expression of osteogenic marker genes was determined by real time PCR.
Results
ESCs cultured with DAG showed by far the largest deposition of calcium phosphate-containing minerals. Starting at day 9 of culture, a strong increase in collagen I mRNA expression was detected in the DAG-treated cells. In BMP-2-treated ESCs the collagen I mRNA induction was less increased. Expression of osteocalcin, a highly specific marker for osteogentic differentiation, showed a double-peaked curve in DAG-treated cells. ESCs cultured in the presence of DAG showed a strong increase in osteocalcin mRNA at day 9 followed by a second peak starting at day 17.
Conclusion
Supplementation of ESC cell cultures with DAG is effective in inducing osteogenic differentiation and appears to be more potent than stimulation with BMP-2 alone. Thus, DAG treatment can be recommended for generating ESC populations with osteogenic differentiation that are intended for use in bone tissue engineering.
doi:10.1186/1746-160X-4-10
PMCID: PMC2443118  PMID: 18544155
9.  Dentin dysplasia type I: a challenge for treatment with dental implants 
Head & Face Medicine  2007;3:31.
Background
Dentin dysplasia type I is characterized by a defect of dentin development with clinical normal appearance of the permanent teeth but no or only rudimentary root formation. Early loss of all teeth and concomitant underdevelopment of the jaws are challenging for successful treatment with dental implants.
Methods
A combination of sinus lifting and onlay bone augmentation based on treatment planning using stereolithographic templates was used in a patient with dentin dysplasia type I to rehabilitate the masticatory function.
Results
(i) a predisposition for an increased and accelerated bone resorption was observed in our patient, (ii) bone augmentation was successful using a mixture of allogenic graft material with autogenous bone preventing fast bone resorption, (iii) surgical planning, based on stereolithographic models and surgical templates, facilitated the accurate placement of dental implants.
Conclusion
Bony augmentation and elaborate treatment planning is helpful for oral rehabilitation of patients with dentin dysplasia type I.
doi:10.1186/1746-160X-3-31
PMCID: PMC1995192  PMID: 17714586
10.  Prospects of micromass culture technology in tissue engineering 
Tissue engineering of bone and cartilage tissue for subsequent implantation is of growing interest in cranio- and maxillofacial surgery. Commonly it is performed by using cells coaxed with scaffolds. Recently, there is a controversy concerning the use of artificial scaffolds compared to the use of a natural matrix. Therefore, new approaches called micromass technology have been invented to overcome these problems by avoiding the need for scaffolds. Technically, cells are dissociated and the dispersed cells are then reaggregated into cellular spheres. The micromass technology approach enables investigators to follow tissue formation from single cell sources to organised spheres in a controlled environment. Thus, the inherent fundamentals of tissue engineering are better revealed. Additionally, as the newly formed tissue is devoid of an artificial material, it resembles more closely the in vivo situation. The purpose of this review is to provide an insight into the fundamentals and the technique of micromass cell culture used to study bone tissue engineering.
doi:10.1186/1746-160X-3-4
PMCID: PMC1781066  PMID: 17212823

Results 1-10 (10)