Immediate Load Protocol for Anterior Maxilla With Cortical Bone From Mandibular Ramus

Bivariate optimization of orthodontic mini-implant thread height and pitch

PURPOSE

Mini-implants have been used as anchorage for years, but failure is common in clinical practice. Mini-implant design is a critical factor affecting its stability. The aim of this study was to evaluate the effect of continuous and simultaneous variations of thread height and pitch on the biomechanical properties of an orthodontic mini-implant.

METHOD

A 3D finite element model, composed of a posterior maxilla section and an orthodontic mini-implant, was created. Mini-implant thread height ranged from 0.10 to 0.40 mm, and thread pitch ranged from 0.50 to 2.00 mm. Effects of the implant thread height and pitch on the maximum Von Mises stresses in maxilla and mini-implant, as well as maximum displacements in the mini-implant, were evaluated by a finite element method. Bivariate analysis was used to determine the optimal range of thread height and pitch.

RESULTS

Variation of thread height and pitch decreased the maximum Von Mises stresses in cortical bone, cancellous bone and mini-implant by 54.9, 78.4 and 23.6 %, respectively. The maximum displacement in the mini-implant decreased by 21.8 %.

CONCLUSION

Maxillary stress and mini-implant stability were influenced by mini-implant thread height and pitch. Increased thread height with a thread pitch of 1.20 mm was better for orthodontic mini-implant in the maxillary posterior region. Thread height played a more significant role than the thread pitch in reducing maxillary stress and enhancing orthodontic mini-implant stability.

Effect of cyclic mechanical stimulation on the expression of osteogenesis genes in human intraoral mesenchymal stromal and progenitor cells

We evaluated the effects of mechanical stimulation on the osteogenic differentiation of human intraoral mesenchymal stem and progenitor cells (MSPCs) using the Flexcell FX5K Tension System that mediated cyclic tensile stretch on the cells. MSPCs were isolated from human mandibular retromolar bones and characterized using flow cytometry. The positive expression of CD73, CD90, and CD105 and negativity for CD14, CD19, CD34, CD45, and HLA-DR confirmed the MSPC phenotype. Mean MSPC doubling time was 30.4 ± 2.1 hrs. The percentage of lactate dehydrogenase (LDH) release showed no significant difference between the mechanically stimulated groups and the unstimulated controls. Reverse transcription quantitative real-time PCR revealed that 10% continuous cyclic strain (0.5 Hz) for 7 and 14 days induced a significant increase in the mRNA expression of the osteogenesis-specific markers type-I collagen (Col1A1), osteonectin (SPARC), bone morphogenetic protein 2 (BMP2), osteopontin (SPP1), and osteocalcin (BGLAP) in osteogenic differentiated MSPCs. Furthermore, mechanically stimulated groups produced significantly higher amounts of calcium deposited into the cultures and alkaline phosphatase (ALP). These results will contribute to a better understanding of strain-induced bone remodelling and will form the basis for the correct choice of applied force in oral and maxillofacial surgery.

Effects of directly autotransplanted tibial bone marrow aspirates on bone regeneration and osseointegration of dental implants

OBJECTIVES

Aim of the pilot trial was to evaluate applicability and effects of directly autotransplanted tibial bone marrow (BM) aspirates on the incorporation of porous bovine bone mineral in a sinus lift model and on the osseointegration of dental implants.

MATERIAL AND METHODS

Six edentulous patients with bilaterally severely resorbed maxillae requiring sinus augmentation and implant treatment were included. During surgery, tibial BM was harvested and added to bone substitute material (Bio-Oss(®) ) at the randomly selected test site. At control sites, augmentation was performed with Bio-Oss(®) alone. The cellular content of each BM aspirate was checked for multipotency and surface antigen expression as quality control. Histomorphometric analysis of biopsies from the augmented sites after 3 and 6 months (during implantation) was used to evaluate effects on bone regeneration. Osseointegration of implants was evaluated with Periotest(®) and radiographic means.

RESULTS

Multipotent cellular content in tibial BM aspirates was comparable to that in punctures from the iliac crest. No significant difference in amount of new bone formation and the integration of bone substitute particles was detected histomorphometrically. Periotest(®) values and radiographs showed successful osseointegration of inserted implants at all sites.

CONCLUSION

Directly autotransplanted tibial BM aspirates did not show beneficial regenerative effects in the small study population (N = 6) of the present pilot trial. However, the proximal tibia proved to be a potential donor site for small quantities of BM. Future trials should clarify whether concentration of tibial BM aspirates could effect higher regenerative potency.

Effects of immediate orthodontic and orthopedic forces on peri-miniscrew bones: histomorphologic and histomorphometric assessment in dogs

Aim. The aim of this study was histomorphologic and histomorphometric evaluation of peri-screw bone after immediate orthodontic and orthopedic forces and comparing them with a control group. Materials and Methods. 18 dual-top miniscrews were inserted in the premolar region of three Iranian dogs. Screws were divided into three groups: (1) the first group undergoing immediate orthodontic force of 300 cN, (2) the second group undergoing immediate orthopedic force of 600 cN and (3) a control group. Screws were explanted with adequate amount of surrounding bone after three months. Bone-screw contact (BSC), percentage of lamellar bone, and percentage of woven bone were evaluated. Wilcoxon and Man Whitney tests were used to analyze the data using SPSS software ver. 15 (α = 0.05). Results. There was no significant difference among the groups in terms of bone-screw contact (P  value = 0.42), percentage of lamellar bone (P  value = 0.83), and percentage of woven bone (P  value = 0.88). Conclusion. By applying orthodontic and orthopedic forces to mini-screws the quality of surrounding bone and osseointegration will not be affected. Clinical Significance. Application of force to mini-screws is helpful in orthodontic-screw therapies.

Immediate implant loading: A case report

Dental implants have long provided an excellent treatment option to restore edentulous spaces. Successful formation of a direct bone to implant interface is the goal in implant therapy. Immediate loading is an alternative to two stage surgical procedure. Improved surgical instrumentation implants design, and surface topography changes the concept of two stages surgical to one stage surgical procedure.

Immediate Load and Esthetic Zone Considerations to Replace Maxillary Incisor Teeth Using a New Zirconia Implant Abutment in the Bone Grafted Anterior Maxilla

The goal of this prospective clinical study is to evaluate a new all-ceramic implant abutment made from zirconium oxide during the immediate load of dental implants placed in the block grafted anterior maxilla. This new zirconia abutment gives the clinician the opportunity to provide the patient with an all-ceramic restorative system (abutment and crown) for an optimum esthetic result and a high level of patient satisfaction. A total of 9 hydroxyapatite-coated dental implants were surgically placed in 9 patients and were immediately loaded 5 to 7 days later with a custom composite provisional restoration that was placed out of functional occlusion. Each prefabricated, natural colored zirconia abutment was shaped and connected to the implant with a titanium screw. Provisional restorations were cemented to the zirconia abutment with the use of temporary cement. Twelve weeks later, the provisional restoration was replaced with an all-ceramic restoration. Over a 52-week observation period, no abutment fractures occurred, and no abutment screw loosening was observed. No implants failed. All 9 patients reported total satisfaction regarding esthetic quality of the all-ceramic restorative system (abutment and implant). Preliminary results of this clinical study indicate that this new zirconia abutment offers the clinician and the patient exceptional strength, optimal esthetics, and simplicity. It is of important clinical significance that use of this all-ceramic abutment eliminates the well-known disadvantages of metal abutments.

Application of orthodontic mini-implants in adolescents

The aim of this study was to determine the success rate of mini-implants in adolescents, and also whether a latent period is necessary and the optimum placement torque in an attempt to improve the success rate in adolescent patients. There were 57 orthodontic patients involved in the study, with ages ranging from 11.7 to 36.1 years, who underwent surgery to insert mini-implants (169 implants). When a mini-implant endured an orthodontic force applied for 6 months or more without any mobility, it was considered a success. The success rate was 63.8% in the early-load group (less than 1-month latent period) of adolescents, 97.2% in the late-load group (3-month latent period) of adolescents and 91.9% in the adult group. The success rate of the early-load group of adolescents was significantly inferior to those of the other groups (P<0.01). In measurements of the placement torque in adolescents, the success rate of the 5-10 N cm group was significantly higher than the other groups only in the maxilla of the early-load group. Although the optimum torque could not be defined, a latent period of 3 months before loading is recommended to improve the success rate of the mini-implant when placed in the alveolar bone in adolescent patients.

Consensus Conference on Immediate Loading: The Single Tooth and Partial Edentulous Areas

PURPOSE

A consensus conference was held to determine what the parameters should be for the immediate functional loading of the single-tooth implant restoration and short-span fixed implant-supported bridgework.

MATERIALS

Forty-one clinicians and researchers presented cases and situations relating to the topic. A panel then distilled questions that were presented to the audience (430) at large. Answers were gleaned to formulate a consensus.

RESULTS

Ten distinct answers evolved that constituted the essence of guidelines for clinicians to be aware of when undertaking immediate loading. These guidelines are contained within the body of the text.

CONCLUSIONS

Extreme caution and adherence to a universal generic protocol are suggested for clinicians who are involved with single-tooth and short-span multiple-teeth implant replacements as related to immediate loading as defined within this text.