Molecular Mechanisms Controlling Bone Formation During Fracture Healing and Distraction Osteogenesis

Fracture healing and distraction osteogenesis have important applications in orthopedic, maxillofacial, and periodontal treatment. In this review, the cellular and molecular mechanisms that regulate fracture repair are contrasted with bone regeneration that occurs during distraction osteogenesis. While both processes have many common features, unique differences are observed in the temporal appearance and expression of specific molecular factors that regulate each. The relative importance of inflammatory cytokines in normal and diabetic healing, the transforming growth factor beta superfamily of bone morphogenetic mediators, and the process of angiogenesis are discussed as they relate to bone repair. A complete summary of biological activities and functions of various bioactive factors may be found at COPE (Cytokines & Cells Online Pathfinder Encyclopedia), http://www.copewithcytokines.de/cope.cgi

Proteolysis of histatins in glandular secretions and whole saliva

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact [email protected] (D.Sc.)--Boston University, Henry M. Goldman School of Dental Medicine, 2004 (Oral Biology).Includes bibliographical references (leaves 102-118).Histatins are a family of small, cationic, histidine-rich proteins present in human salivary secretions (Oppenheim et al., 1988). The major ones are histatin 1 (38 amino acids), histatin 3 (32 amino acids) and histatin 5 (24 amino acids), which constitute 80% of total histatins in saliva. So far only two genes for histatins have been identified, the HIS 1 gene, encoding histatin 1 and the HIS 2 gene encoding histatin 3 (Sabatini and Azen, 1989). No gene for histatin 5 has been found despite the fact that its concentration in parotid secretion (PS) and submandibular/sublingual (SMSL) secretion is comparable to that of histatin 1 and 3. In order to establish or predict histatin function in the oral cavity, it is important to know their concentrations in the various salivary secretions. Therefore, the first objective of this study is to isolate and quantify the major histatins in parotid secretion, submandibular/sublingual secretion, and in whole saliva. The recently developed zinc precipitation method was used (Flora et al., 2001) to obtain a fraction selectively enriched in histatins. The major histatins were subsequently separated by reversed-phase chromatographic procedures, and histatin concentrations were determined by comparison to standard curves for each of the histatins. The concentrations of the total major histatins in PS, SMSL and whole saliva supernatant (CHWS) from four individuals were found to range between 4.6 to 5.6 mg% in PS and from 9.8 to 18.4 mg% in SM/SL but only from 0.2 to 0.6 mg% in CHWS. Histatin levels were also compared in PS from a group of healthy individuals and periodontitis patients. The major histatin levels were higher in periodontitis patients than in healthy individuals but the differences were not statically significant due to large inter-individual variations within one group. Notably, the concentrations of histatins in CHWS were much lower than the levels in pure glandular secretions. The second objective of this study was to investigate the reason for this. It was investigated whether histatins in whole saliva were bound to bacteria and cells rather than being present in a free form, the efficiency of the zinc precipitation method in CHWS was evaluated, and the susceptibility of histatins to proteolysis in CHWS was established. It can be concluded from our observations that histatins are removed from the solute phase of saliva by over 50% upon centrifugation, that with the zinc precipitation method, 86% of the histatins remaining in the solute phase can be precipitated and that histatins are quickly degraded by proteolytic enzymes in CHWS. All three factors likely contribute to the low histatin levels observed in CHWS. The proteolytic degradation of histatins in CHWS was investigated in more detail by adding individual histatins to CHWS and by mixing PS or SMSL secretion with CHWS. To determine the primary cleavage sites in histatins, the histatin degradation patterns generated by CHWS were compared to degradation patterns generated by pure proteolytic enzymes that are known to be present in whole saliva. In particular histatin 3 and 5 added to CHWS were quickly degraded, and the major enzymes responsible for this appear to be trypsin and chymotrypsin. Interestingly histatin 1 was much more resistant to proteolysis than histatin 3 and 5. Also in this study, the stability of native histatins in PS, SMSL and CHWS was investigated. In these experiments, PS, SMSL and CHWS samples were incubated individually for a 0-120 hr time interval at 37°C. At various time intervals, aliquots were removed, boiled and analyzed by cationic PAGE. Histatin 3 in both PS and SMSL started to disappear after an hour and was completely abolished after six hours of incubation. On the other hand, histatin 1 remained stable in both glandular secretions over the entire 120 hr incubation period. It can be concluded that PS and SM/SL secretion possess minor auto-proteolytic activities which are capable of degrading histatin 3 and 5 but not histatin 1. The high resistance of native histatin 1 was an observation of interest. Since the amino acid sequences are very similar, the number of predicted proteolytic degradation sites in histatin 1 and 3 are virtually identical. It was investigated whether the proteolytic resistance of histatin 1 could be attributed to the phosphate group that is covalently linked to the amino acid serine at position 2 in histatin 1, but not in histatin 3. For this purpose, native, phosphorylated, histatin 1 and recombinant, non-phosphorylated, histatin 1 were incubated with CHWS and the proteolytic breakdown products were analyzed by cationic PAGE. Interestingly, while recombinant non-phosphorylated histatin 1 disappeared, native phosphorylated histatin 1 showed only minor losses. This result indicates that the presence of a phosphate group in position 2 in the 38 amino acid polypeptide structure of histatin 1 essentially protects this protein against proteolytic degradation

Disability and the impact of need for periodontal care on quality of life: A cross-sectional study

Objective The need for periodontal care may negatively impact daily life. We compared the need for periodontal care and its impact on daily life between disabled and healthy adults in the Eastern Province, Saudi Arabia. Methods In this cross-sectional study of 819 adults, a questionnaire was used to assess personal background factors; the impact of periodontitis on pain, avoiding foods, embarrassment, sleeplessness, work absence, and discontinuing daily activities; and risk factors (smoking, diabetes, toothbrushing, insurance, professional tooth cleaning, and dental visits). The outcome was clinically assessed need for periodontal care impacting daily life. The relationship between the outcome and risk factors adjusted for personal background and disability was assessed using ordinal regression. Results Healthy and disabled persons had a high need for periodontal care (66.8%). Current smokers had a higher likelihood and health-insured persons had a lower likelihood of need for periodontal care impacting daily life regardless of whether disability was considered. Conclusions Most adults needed periodontal care, and disabled persons experienced a greater impact on life. Current smokers and uninsured persons were more likely to need periodontal care impacting daily life. Our findings are important for the prevention of periodontitis through tobacco cessation and extending insurance coverage. </jats:sec

Localized ridge augmentation in the anterior maxilla using titanium mesh, an alloplast, and a nano-bone graft: a case report

Alveolar ridge deficiency is considered a major limitation for successful implant placement, as well as for the long-term success rate, especially in the anterior maxillary region. Various approaches have been developed to increase bone volume. Among those approaches, inlay and onlay grafts, alveolar ridge distraction, and guided bone regeneration have been suggested. The use of titanium mesh is a reliable method for ridge augmentation. We describe a patient who presented with a localized, combined, horizontal and vertical ridge defect in the anterior maxilla. The patient was treated using titanium mesh and alloplast material mixed with a nano-bone graft to treat the localized ridge deformity for future implant installation. The clinical and radiographic presentation, as well as relevant literature, are presented. </jats:p

Case Report: Combining Molar Interradicular Osteotomy With Immediate Implant Placement: A Three-Year Case-Series Study

Background: Immediate implant placement in the area of multirooted molars includes many anatomical challenges, particularly with osteotomy preparation in the interradicular bone.Methods: In this article, we are reporting ten cases in which implant beds were prepared before root extraction. After coronectomy, pre-extractive interradicular implant bed preparations were performed through the retained root complexes. A dimple in the roof of the furcation was created using a no. 8 round surgical bur. The osteotomies were then completed through the tooth’s initially retained root complex in the regular sequence of drilling. Before implant placement, the remaining root segments were removed. The retained root parts guided the osteotomy drills and allowed for precise positioning and angulation of the implant bed preparation with respect to the emergence profile of the tooth.Results: Data from a 3-year follow-up of the crestal bone showed good bone levels in relation to the implant platform.Conclusion: The technique described permitted accurate implant placement in the prepared osteotomy, thus enabling immediate implant positioning in multirooted extraction sites.</jats:p

A comparative study of bovine bone used alone and in combination with transforming growth factor-beta for the treatment of periodontal osseous defects in humans

Objectives: Transforming growth factor-betas (TGFβs) are multifunctional growth factors with a broad range of biological activities in various cell types in many different tissues. The purpose of this study was to evaluate the treatment of intrabony defects with anorganic bovine bone mineral matrix combined with TGFβ-1 with the use of anorganic bovine bone alone. Materials and Methods: Thirty-two sites from sixteen patients were selected using a split-mouth study design for each patient, determined randomly through a biased coin randomization. One site received a mucoperiosteal flap, and the osseous defect was filled with the combined therapy (Group 1). The other site treated was with anorganic bovine bone alone and served as a control (Group 2). All the treated sites were covered with a bioabsorbable collagen membrane. The clinical parameters and radiographic follow-up examinations were recorded after 3, 6, 9, and 12 months. Results: Clinically, there was a statistically significant gain in the clinical attachment level (+5.03 ΁ 0.14 mm) and a statistically significant reduction of pocket probing depth (−5.16 mm ΁ 0.13) for Group 1 sites compared to sites in Group 2 (P ≤ 0.01). In addition, there were significant differences in bone density and a significant decrease of marginal bone loss after the combined therapy compared with the use of anorganic bovine bone alone (P ≤ 0.01). Conclusion: The use of anorganic bovine bone mineral matrix combined with TGFβ-1 seemed to be effective in the treatment of intrabony defects. This showed an improvement in the clinical outcome of periodontal therapy superior to the use of anorganic bovine bone on its own

Comparative study of the shear bond strength of composite resin bonded to enamel treated with acid etchant and erbium, chromium: Yttrium, scandium, gallium, garnet laser

Aim: The purpose of this investigation is in vitro comparison of the shear bond strength (SBS) of composite resin bonded to enamel pretreated with an acid etchant against enamel etched with erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr:YSGG) laser. Materials and Methods: Sixty premolars were sectioned mesiodistally and these 120 specimens were separated into two groups of 60 each (Groups A and B). In Group A (buccal surfaces), enamel surface was etched using 37% phosphoric acid for 15 s. In Group B (lingual surfaces), enamel was laser-etched at 2W for 10 s by Er, Cr:YSGG laser operational at 2780 nm with pulse duration of 140 μs and a frequency of 20 Hz. After application of bonding agent on all test samples, a transparent plastic cylinder of 1.5 mm × 3 mm was loaded with composite and bonded by light curing for 20 s. All the samples were subjected to SBS analysis using Instron Universal testing machine. Failure modes were observed under light microscope and grouped as adhesive, cohesive, and mixed. Failure mode distributions were compared using the Chi-square test. Results: SBS values obtained for acid-etched enamel were in the range of 7.12–28.36 megapascals (MPa) and for laser-etched enamel were in the range of 6.23–23.35 MPa. Mean SBS for acid-etched enamel was 15.77 ± 4.38 MPa, which was considerably greater (P < 0.01) than laser-etched enamel 11.24 ± 3.76 MPa. The Chi-square test revealed that the groups showed no statistically significant differences in bond failure modes. Conclusions: We concluded that the mean SBS of composite with acid etching is significantly higher as compared to Er, Cr: YSGG (operated at 2W for 10 s) laser-etched enamel

Effect of erbium laser on microtensile bond strength of fissure sealant in primary teeth: An in vitro study

Background: Laser etching has several advantages as compared with conventional acid etching. However, results of earlier studies on conditioning surfaces with erbium, chromium:yttrium–scandium–gallium–garnet (Er, Cr:YSGG) before application of the fissure sealant have been inconclusive. Aim: The study aimed to evaluate the microtensile strength of resin-based fissure sealant bonded to primary enamel conditioned by Er, Cr:YSGG laser with varying power outputs. Materials and Methods: Fifty sound primary first molars were randomized into the following five groups based on pretreatment choice: Group 1: 3.5 W laser etching + acid etching; Group 2: 2.5 W laser etching + acid etching; Group 3: 3.5 W laser etching with no acid; Group 4: 2.5 W laser etching with no acid and Group 5: acid etching with no laser. Acid etch was performed with 35% orthophosphoric acid for 30 s. Laser etching was performed with Er, Cr:YSGG (2780 nm) laser using G6 tips and 600 μm diameter, 2.5 W or 3.5 W power outputs, pulse duration of 140 μs and a repetition rate of 20 Hz. Sealant was applied on the buccal surface followed by an incremental buildup with composite resin. Microtensile bond strength was assessed and compared among the five groups using one- and two-way ANOVA. Results: There was no statistical difference in the mean bond strength between groups except in Group 4 (9.66 MPa) (Group 1: 15.57 MPa; Group 2: 14.18 MPa; Group 3: 14.78 MPa; Group 5: 14.63 MPa). Conclusion: Pretreatment with 3.5 W Er, Cr:YSGG laser alone results in microtensile bond strengths similar to that produced by acid etching, indicating that enamel etching using 3.5 W Er, Cr:YSGG laser would result in the long-term success of pit and fissure sealants in primary teeth