Justin W. Sanders
Abstract
“We’re always looking for more efficient ways to do things for the patient,” Roth says, “to make the experience better, to provide better customer service, and to improve the quality of the end result. There’s nobody looking over your shoulder in dentistry but you. There’s nobody challenging you to be better unless you’re challenging yourself. And it’s very easy to be OK with the status quo, but if you have that mentality you can be left behind.
Guided bone regeneration to repair an osseous defect.
Carvalho RS1, Nelson D, Kelderman H, Wise R.
The
ultimate goal of orthodontic therapy is to establish functional and
esthetic dental relationships in a balanced facial pattern. In patients
with compromised periodontal support, the use of multidisciplinary
treatment plans is essential in attaining these goals. This case report
includes a thorough documentation of the orthodontic and periodontal
treatments to demonstrate the effectiveness of guided bone regenerative
procedures combined with a bone allograft to aid in correcting a dental
malocclusion.
Exploring myths of Invisalign with Dr. Menachem Roth.
Baloul SS1, Gerstenfeld LC, Morgan EF, Carvalho RS1, Van Dyke TE, Kantarci A.
Background and Purpose
The
aim of this study was to test if corticotomy-induced osteoclastogenesis
and bone remodeling underlie orthodontic tooth movement and how
selective alveolar decortication enhances the rate of tooth movement.
Menachem Roth, DMD, MMSc
Abstract
As a general rule, cases that lend themselves to canine substitution would be those with a reasonable Class I or mild Class II profile, a Class II dental relationship, and minimal lower arch crowding; or a Class I dental relationship with crowding in the lower arch that requires premolar extraction or dentoalveolar protrusion.1-2 A typical space-opening implant case has one or both maxillary lateral incisors are missing, an acceptable profile, Class I occlusion, and spacing or minimal crowding with the spaces for the lateral incisors intact. Only a limited number of patients fall into these more clear-cut categories.
Carvalho RS1, Bumann A, Schaffer JL, Gerstenfeld LC.
Abstract
Previous studies have demonstrated that both mechanical perturbation and
cell adhesion induced the expression of osteopontin (opn) by
osteoblasts (Carvalho et al. [1998] J. Cell. Biochem. 70:376-390). The
present study examined if these same stimuli on osteoblasts would induce
the expression of other integrin binding proteins, specifically
fibronectin (fn) and bone sialoprotein (bsp). All three genes showed
three- to four-fold maximal induction in response to both cell adhesion
and a single 2-h period of an applied spatially uniform, dynamic biaxial
strain of 1.3% at 0.25 Hz. Each gene, however, responded with a
different time course of induction to mechanical strain, with bsp, fn,
and opn showing their maximal response at 1, 3, and 9 h, respectively,
after the perturbation period. In contrast, peak induction to cell
adhesion was observed at 24 h for bsp and opn, while fn levels peaked at
8 h. Interestingly, while both opn and fn mRNA expression returned to
base line after cell adhesion, bsp mRNA levels remained elevated.
Examination of collagen type I and osteocalcin mRNAs showed unaltered
levels of expression in response to either type of perturbation. A
common feature of the signal transduction pathways, which mediate the
gene expression in response to both cell adhesion and mechanical
perturbation, was the activation of specific tyrosine kinases based on
the ablation of the induction of these genes by the tyrosine kinase
inhibitor genistein. While cycloheximide blocked the induction of all
three mRNAs in response cell adhesion, it failed to block the induction
of any of these genes in response to mechanical perturbation. Such
results suggest that the induction of these genes after mechanical
perturbation was mediated by an immediate response to signal
transduction, while cell adhesion mediated effects secondary to signal
transduction. Depolymerization of microfilaments with cytochalasin D had
no effect on the overall expression of any of these genes in response
to cell adhesion and only blocked the induction of opn expression in
response to mechanical perturbation. These results suggest that
cytoskeletal integrity is only selectively important in the signal
transduction of certain types of stimuli and for the regulation of
certain genes. In summary, both mechanical perturbation and cell
adhesion stimulated the expression of integrin binding proteins.
Furthermore, while there are common features in the signal transduction
processes that mediate the induction of these genes in response to both
stimuli, specific genes are separately regulated by precise mechanisms
that are unique to both forms of stimuli.
Selective adhesion of osteoblastic cells to different integrin ligands induces osteopontin gene expression.
Carvalho RS1, Kostenuik PJ, Salih E, Bumann A, Gerstenfeld LC.
Abstract
Skeletal homeostasis is partly regulated by the mechanical environment
and specific signals generated by a cell's adhesion to the matrix.
Previous studies demonstrated that osteopontin (OPN) expression is
stimulated in response to both cellular adhesion and mechanical
stimulation. The present studies examine if specific integrin ligands
mediate osteoblast selective adhesion and whether opn mRNA expression is
induced in response to these same ligands. Embryonic chicken calvaria
osteoblastic cells were plated on bacteriological dishes coated with
fibronectin (FN), collagen type I (Col1), denatured collagen/gelatin
(G), OPN, vitronectin (VN), laminin (LN) or albumin (BSA). Osteoblastic
cells were shown to selectively adhere to FN, Col1, G and LN, yet not to
VN, OPN or BSA. Opn mRNA expression was induced by adhesion to Col1,
FN, LN and G, but neither OPN nor VN induced this expression.
Examination of the activation of the protein kinases A and C second
signaling systems showed that only adhesion to FN induced protein kinase
A and protein kinase C (PKC) activity while adherence to Col1 induced
PKC. Evaluation of the intracellular distribution of focal adhesion
kinase (FAK) and p-tyrosine within cells after adherence to FN, VN or
BSA demonstrated that adherence to FN stimulated FAK translocation from
the nucleus to the cytoplasm and high levels of p-tyrosine localization
at the cell surface. However, cell adherence to VN or BSA did not show
these morphological changes. These data illustrate that osteoblast
selective adhesion is mediated by specific integrin ligands, and
induction of intracellular second signal kinase activity is related to
the nature of the ligand.