Effects of precementation on minimizing residual cement around the marginal area of dental implants.

STATEMENT OF PROBLEM: Residual cement is detrimental to the long-term success of dental implants with a cement-retained restoration. The complete elimination of excess cement remains a challenge. PURPOSE: The purpose of this in vitro study was to evaluate the effects of precementation technique on minimizing the residual cement and retention of restorations. MATERIAL AND METHODS: Four custom cobalt-chromium alloy (Co-Cr) abutments were manufactured by computer-aided design and computer-aided manufacturing (CAD-CAM) as precementation abutments with height and radius reductions of 25 µm (A25), 50 µm (A50), 75 µm (A75), and 100 µm (A100). Fifty CAD-CAM-fabricated standard Co-Cr abutments and corresponding crowns were randomly matched and treated as follows: 10 specimens were cemented with the conventional cementation procedure with glass ionomer cement (G0), and 40 were precemented with precementation abutments (n=10) before the definitive cementation with standard abutments (G25, G50, G75, G100). The weight of the cement in the cement space was calculated, and the marginal sealing was evaluated by using a stereoscopic microscope. The effects of precementation with resin cement on minimizing residual cement around the marginal area of dental implants were further evaluated extraorally. The influence of precementation with glass ionomer and resin cement on the retention force was analyzed by using a universal testing machine at a crosshead speed of 0.5 mm/min. One-way ANOVA was used to analyze cement mass and marginal sealing values. Two-way ANOVA was used to compare the retention forces (α=.05). RESULTS: The cement weight of G50 (7.2 ±0.6 mg) was significantly higher than that of G25 (6.0 ±1.1 mg, P<.05), while no significant differences in cement weights were found among G50, G75, and G100. Consistently, the G50, G75, and G100 had higher marginal sealing values than that of the G25 (P<.01). Extraoral experiments showed that the precementation with A50 reduced subgingival residual cement without affecting retention. CONCLUSIONS: These in vitro results suggest that precementation with a precisely manufactured precementation abutment minimized the residual cement around implant abutments, and 50 µm could be a preferable precementation space.

Positive effect of strontium-oxide layer on the osseointegration of moderately rough titanium surface in non-osteoporotic rabbits.

OBJECTIVES: To evaluate the effect of strontium-oxide layer on new bone formation and osseointegration of sandblasted large-grit double-acid-etched (SLA) implant. MATERIAL AND METHODS: Strontium-oxide layer on the SLA surface was produced by hydrothermal treatment using a Sr-containing solution. The surface topographies, roughness, hardness values, chemical elements and ionic release of SLA and the strontium-containing SLA (Sr-SLA) surface were measured by special instruments separately. Sixty-four SLA and Sr-SLA implants were inserted into the proximal tibiae and femoral condyles of sixteen non-osteoporotic New Zealand white rabbits. The biological effects were evaluated by removal torque (RTQ) testing and histomorphometric analysis after 3 and 6 weeks of implantation. RESULTS: The surface characteristics showed Sr-SLA surfaces with dotted nanostructures can release appropriate amount of strontium ions into surrounding tissue till 14 days. In vivo, the Sr-SLA implants presented significantly higher RTQ than SLA implants at 3 and 6 weeks (P < 0.05). The Sr-SLA implants presented higher bone-to-implant contact (BIC) than SLA implants in cortical bone at 3 and 6 weeks (P < 0.05). The bone area was slightly higher for the Sr-SLA implants at 3 and 6 weeks (P > 0.05). CONCLUSIONS: The strontium-oxide layer on the SLA surface has the potential to improve implant osseointegration in non-osteoporotic rabbits.

Long-term outcomes of osteotome sinus floor elevation without bone grafts: a clinical retrospective study of 4-9 years.

OBJECTIVE: To evaluate the long-term clinical and radiographic outcomes of dental implant placed using osteotome sinus floor elevation (OSFE) without bone grafts, and to analyze the potential influence factors of implant survival and endo-sinus bone remodeling. MATERIAL AND METHODS: A retrospective study design was adopted. The clinical and radiographic data of 96 implants in 80 patients were collected after 4-9 (mean 5.40) years follow-up. Implant failures, peri-implant marginal bone loss (MBL), and endo-sinus bone remodeling on the radiographs were evaluated. A life-table analysis was used to assess the implant survival. Statistical models were established to investigate the potential influence factors of implant survival and endo-sinus bone gain (ESBG). RESULTS: In total, nine implants in seven patients failed, giving the 9-year cumulative survival rates of 90.6% and 91.3% for implant-based analysis and patient-based analysis, respectively. The mean MBL between implant installation and the 4- and 9-year follow-up visit was 0.46 ± 0.88 and 0.50 ± 1.69 mm, respectively. The average ESBG on radiographs was 2.95 ± 1.25 and 2.16 ± 1.13 mm at the 4- and 9-year follow-up. The final ESBG was found to be positively correlated to implant protrusion length after surgery without any other factors related. The implant survival rate was significantly lower in severe atrophic site (residual bone height <5 mm). CONCLUSION: Osteotome sinus floor elevation without bone grafts is a predictable treatment modality in the long run. But it should be used with caution when the initial bone height of the edentulous site is lower than 5 mm. The final endo-sinus bone height was found to be positively correlated to implant protrusion length measured on radiographs immediately after implant installation.

Effect of sinus membrane perforation on the survival of implants placed in combination with osteotome sinus floor elevation.

This study was conducted to evaluate implant survival with regard to effects of sinus membrane perforation that occurred during osteotome sinus floor elevation (OSFE). The study group consisted of 42 patients with edentulous posterior maxilla. Implants placement combined with OSFE without a grafting material was performed. All patients underwent a radiographic examination before surgery, to reveal the periimplant bone formation immediately after implant placement and 6 to 33 months later. Sinus membrane perforations were detected in 6 patients, and 6 implants were inserted in 6 sinus sites. No infection occurred in all sites, and all implants succeeded in the observation follow-up period. There was a 100% survival rate of implant in perforated sinuses, the same as in intact sinuses. Within the limits of this study, we can conclude that perforation of the sinus membrane does not compromise the short-term survival of dental implants placed in combination with OSFE.

Safety of individual medication of Ma Qian Zi (semen strychni) based upon assessment of therapeutic effects of Guo's therapy against moderate fluorosis of bone.

OBJECTIVE: To assess the safety of individual medication of Guo's Ma Qian Decoction on the basis of effective treatment of fluorosis of bone with Guo's therapy. METHODS: One hundred and fourteen cases of moderate fluorosis of bone were randomly divided into a treatment group (n = 60) and a control group (n = 54) between December 2007 and August 2009 by using the block randomized method and a central random system. At the same time of basic treatment, the patients in the treatment group were orally administrated with Guo's Ma Qian Decoction. The initial dose of Ma Qian Zi (Semen Strychni) was 0.4 g and increased by 0.05 g every two days, with the doses of other drugs unchanged, until the patient had "nux vomica response". For the patients with no "nux vomica response", the dosage was continued to increase and the maximum dosage was not more than 1.2 g/day. The control group was treated with decoction placebo. The changes of strychnine and brucine contents before and after processing and after decoction of Ma Qian Zi (Semen Strychni) were determined with reversed-phase high-performance liquid chromatography, which were controlled within ranges stipulated in the Pharmacopeia; Adverse events were analyzed; Blood strychnine and brucine contents in 10 cases who had taken the drugs were determined. RESULTS: 1) Strychnine (2.125%) and brucine (1.425%) contents before processing of Ma Qian Zi and 1.88% and 1.31% after processing all conformed with the standards of strychnine (1.2-2.2%) and brucine (no less than 0.8%) stipulated in the Pharmacopeia. When the maximum dosage of Ma Qian Zi was 1.2 g/day, strychnine in the decoction was 11.17 mg and brucine was 7.44 mg, which all conformed with the maximum limited amount (strychnine 13.32 and brucine no less than 4.8 mg) stipulated in the Pharmacopeia. 2) Eight cases had "nux vomica response" in the treatment group and one case in the control group, with a significant difference between the two groups (P < 0.05). 3) Altogether 18 cases had adverse events, with an incidence rate of 15.38% (8 cases) in the treatment group and 18.52% (10 cases) in the control group, with no difference between the two groups (P > 0.05); Among them, 10 cases (8.77%) with the adverse event were not related with therapeutic drugs, with an incidence rate of 6.67% (4 cases) in the treatment and 11.11% (6 cases) in the control group, with no significant difference between the two groups (P > 0.05). Seven cases had suspicious relative adverse events, the risk in the treatment group was 0.658 times of the control group, with no significant difference (P > 0.05), and one case had the toxic reaction of nux-vomica seed. 4) Strychnine and brucine were unable to be detected in the blood in all points of time in the 10 cases who had taken the drugs, indicating that plasma strychnine and brucine contents were lower than the minimum detectable amount (10 ng), and accumulation of strychnine and brucine were not found in blood of the patient during and after administration for 8 weeks. CONCLUSION: The individual medication of Ma Qian Zi (Semen Strychni) in the Guo's therapy has a better safety.

Trismus originating from rare fungal myositis in pterygoid muscles: A case report.

BACKGROUND: Trismus is a common problem with various causes. Any abnormal conditions of relevant anatomic structures that disturb the free movement of the jaw might provoke trismus. Trismus has a detrimental effect on the quality of life. The outcome of this abnormality is critically dependent on timely diagnosis and treatment, and it is difficult to identify the true origin in some cases. We present a rare case of trismus due to fungal myositis in the pterygoid muscle, excluding any other possible pathogenesis. CASE SUMMARY: The patient presented with a 2-mo history of restricted mouth opening. Computed tomography showed obvious enlargement of the left pterygoid muscles. Furthermore, the patient had trismus without obvious predisposing causes. The primary diagnosis was pterygoid myosarcoma. Consequently, lesionectomy of the left pterygoid muscle was performed. Intraoperative frozen biopsy implied the possibility of an uncommon infection. Postoperative pathologic examination confirmed myositis and necrosis in the pterygoid muscle. Fungi were detected in both muscle tissue and surrounding necrotic tissue. The patient recovered well with antifungal therapy and mouth opening exercises. The rarity of fungal myositis may be responsible for the misdiagnosis. Although the origin of pathogenic fungi is still unknown, we believe that both hematogenous spread and local invasion could be the most likely sources. To the best of our knowledge, this is the first case in the literature that reported fungal myositis in pterygoid muscles as the only reason that results in trismus. CONCLUSION: Surgeons should remain vigilant to the possibility of trismus originating from fungal myositis.

Does endodontic post space irrigation affect smear layer removal and bonding effectiveness?

The effect of different post space irrigants on smear layer removal and dentin bond strength was evaluated. Sixty-six extracted sound maxillary central incisors were endodontically treated. After post space preparation, the teeth were assigned to three groups of 22 teeth each. The teeth of these three groups were irrigated for 1 min with 17% ethylenediaminetetracetic acid (EDTA) (group 1), 5.25% sodium hypochlorite (NaOCl) (group 2), or 0.9% sodium chloride (NaCl) (group 3). In each group, eight specimens were split longitudinally for smear layer evaluation, and the other fourteen specimens were filled with a self-etching adhesive system (Panavia F). Four of 14 specimens of each group were prepared for evaluation of the resin-dentin interdiffusion zone (RDIZ) and resin tags, and the other 10 specimens were serially sectioned for push-out test analysis. Smear layer removal and bond strength were affected by different post space irrigants. EDTA removed the smear layer extremely effectively and, as a result, improved the bond strength at each region (apical, middle, and coronal) of the roots. Resin tag formation and the RDIZ were also affected by different irrigants and in accordance with bond strength. Therefore, removal of the smear layer use a self-etching luting system plays an important role in bonding effectiveness.

Effect of the Wnt signal-RANKL/OPG axis on the enhanced osteogenic integration of a lithium incorporated surface.

Bone remolding involves the formation of new bone by osteoblasts and the absorption of old bones by osteoclasts. Due to the vital role of osteoblasts and osteoclasts during bone regeneration, it might be feasible to promote osseointegration around the titanium implants by stimulating osteoblasts and inhibiting osteoclasts by modifying the surfaces of the implants. Lithium is used in the treatment of psychiatric patients, and it may be associated with osteogenesis. In this study, lithium was incorporated with sandblasted, large-grit and acid-etched titanium implants via a hydrothermal treatment. In vitro, the nano-scale surface enhanced the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs). Moreover, the SLA-Li surface displayed a negative effect on the process of osteoclastogenesis. Further mechanism analysis indicated that the canonical Wnt/ß-catenin signaling pathway was activated according to the results of RT-PCR and western blotting. More importantly, the RANKL/OPG signaling axis was also involved in these effects on the SLA-Li surface. The experiments in vivo proved that the SLA-Li surface could induce the bone formation and osseointegration during the early osseointegration after the dental implant surgery. These results suggested that bone homeostasis could be manipulated by an SLA-Li surface, which implied that this new surface might serve as a promising material for clinical application in the future.

Influence of Lateral Windows with Decreased Vertical Height Following Maxillary Sinus Floor Augmentation: A 1-year Clinical and Radiographic Study.

PURPOSE: To verify whether lateral sinus floor elevation (LSFE) with the vertical height of the osteotomy decreased to 3 to 5 mm can achieve improvement compared with a conventional lateral window in terms of implant survival, graft stability, and related complications. MATERIALS AND METHODS: Of the 49 patients who were selected for inclusion in this retrospective study, 25 patients were in the test group and 24 were in the control group based on the vertical height of the lateral window. Each patient received the LSFE treatment using deproteinized bovine bone mineral (DBBM) based on the two different vertical heights of the lateral window (test group: 3 to 5 mm; control group: 6 to 8 mm in vertical height). Residual bone dimensions were measured preoperatively, and graft dimensions were measured immediately after the procedure (baseline), 6 months (T1), and 1 year (T2) postoperatively on the basis of cone beam computed tomography (CBCT) scans. CBCT scan data at the baseline were analyzed with image processing software to evaluate the volume of augmented material, and they were transformed into three-dimensional reconstruction images to calibrate the window dimension. Implant failure and recorded intraoperative and postoperative complications were counted. RESULTS: A prominent augmented graft height was obtained in both groups (test group: 9.48 ± 3.27 mm; control group: 10.44 ± 3.01 mm) with no significant difference; likewise, no difference was observed concerning augmented graft volume. Neither cumulative survival rate (CSR) nor augmented graft height decrement had any statistical intergroup difference during each follow-up interval. CSRs were detected as 100% for the test group and 94.28% and 91.67% for the control group based on implants and patients, respectively. Intraoperative membrane perforation was reported in two cases with a few nosebleeds the first night in the test group, while one case occurred in the control group. All the perforations were successfully sealed intraoperatively by a collagen membrane. CONCLUSION: Osteotomy of LSFE with decreased vertical height yielded similar results to the control group with conventional dimensions in terms of implant survival, graft stability, and related complications with 1 year of follow-up. Notwithstanding, a prospective split-mouth randomized controlled trial with long-term observation is imperative to further investigate the influence of decreased vertical height of the lateral window on maturation and consolidation of DBBM.

Primary small cell carcinoma with neuroendocrine properties of the mandible: A case report and literature review.

Small-cell carcinomas at extrapulmonary primary sites are rare but they have been documented to arise at various locations. We report a case of small-cell carcinoma arising in the mandible, which has so far not been reported in the literature. A 37-year-old male patient underwent partial resection of the left mandible and adjuvant chemotherapy. Immunohistochemistry confirmed the diagnosis of small-cell carcinoma with neuroendocrine properties. The patient has been free of disease for 18 months after receiving treatment and was alive at the time of writing. We recommend surgical resection followed by chemotherapy for managing small-cell carcinomas in the mandibular region.

[Sternocleidomastoid myocutaneous flap for reconstruction after resection of carcinoma in floor of mouth].

OBJECTIVE: To evaluate the clinic outcome and indications of sternocleidomastoid (SCM) myocutaneous flap for reconstruction after resection of carcinoma in floor of mouth. METHODS: Thirty-two patients underwent SCM myocutaneous flap for reconstruction of the floor of mouth were reviewed. According to the clinical data and the follow-up, the appearance and function were analyzed. RESULTS: Only one myocutaneous flap was partial necrosis in termination of the flap, and growth with granular. In eight cases, partial epidermal loss over the skin paddle occurred with secondary healing with mucosal epithelium. All patients had oral diet with good separation of the oral floor and the tongue, and had no difficulty in speech intelligibility. The patients' appearance, function and the overall quality of life were improved. CONCLUSION: The SCM myocutaneous flap appears to be easy to use and suitable for reconstruction of the defect after resection of oral floor carcinoma, the indications of this flap should be selected carefully.

[Tissue engineered bone reconstruction with modified PLGA/Type-I collagen compound scaffold].

OBJECTIVE: To fabricate bone grafts by bone marrow stromal cell combined with modified PLGA/Type-I collagen compound scaffold using tissue engineering method. METHODS: The modified PLGA/Type-I collagen compound scaffold was fabricated. The rabbit primary cultured osteoblasts were identified and seeded onto the modified compound scaffold for one week in vitro. The adhesion and growth of cells were observed with scanning electron microscope. The complex of cells and scaffold was implanted into the subcutaneous region of rabbits and new bone formation was evaluated. RESULTS: The rabbit bone marrow stromal cells were induced and differentiated into osteoblasts. The adhesion and growth of osteoblasts in cluster were observed on the surface of scaffolds. New bone formation was observed at one month postoperatively and active osteoblasts were found on the surface of the newly formed bone in vivo. CONCLUSION: The complex of PLGA and type-I collagen is an appropriate biodegradable scaffold and can be applied in bone tissue engineering.

Influence of orthotropy on biomechanics of peri-implant bone in complete mandible model with full dentition.

OBJECTIVE: The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity. MATERIALS AND METHODS: Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model. RESULTS: The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin. CONCLUSION: The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

Chronological changes in the microstructure of bone during peri-implant healing: a microcomputed tomographic evaluation.

Our objectives were to examine the titanium-bone interfaces chronologically and to clarify the process of osseointegration using microcomputed tomography (microCT). The mandibular premolars of 3 dogs were extracted and 12 weeks later 2 Straumann dental implants were installed in each quadrant. The microstructural changes at the bone-implant interface at the first, fourth, and eighth weeks after installation were evaluated by microCT and a 3-dimensional image was constructed. The microstructural measurements at the bone-implant interface, including the trabecular number (Tb.N), bone volume fraction (BV/TV), structure model index (SMI), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and connectivity density (Conn.D), were measured. Experimental outcomes were analysed for correlations between time and microstructural variables of trabecular bone. Tb.N increased significantly during the eighth week compared with that during the first and fourth week (p=0.001, 0.002). BV/TV increased generally with time and there were significant differences (p=0.003) between each time group. While Tb.Sp decreased with time and changed significantly during the eighth week compared with that during the first week (p=0.021), differences in SMI, Tb.Th and Conn.D did not differ significantly according to time of implant. The significant increase in the Tb.N and BV/TV during the eighth week after insertion of implants indicates that the formation of new bone before the eighth week is the key to osseointegration.

Optimal enamel conditioning strategy for rebonding orthodontic brackets: a laboratory study.

OBJECTIVE: To compare the conventional etching and primer method (CEP) and the self-etching primer method (SEP) in rebonding brackets. METHODS: Forty human maxillary second premolars extracted for orthodontic purpose were randomly divided into 4 equal groups. Group 1 and Group 2 were bonded using the CEP method; Group 3 and Group 4 using the SEP method. All the brackets were debonded and 40 new brackets were rebonded with four different protocols after surface cleaning: Group 1: CEP + adhesive; Group 2: CEP without etch step + adhesive; Group 3: SEP + adhesive; Group 4: non-acidic primer + adhesive. Then, the shear bond strength (SBS) of each group was tested and the measurements of adhesive remnant index scores (ARI) and SEM examination were performed. RESULTS: The mean SBSs for Group 1, 2, 3 and 4 were 14.18, 6.57, 11.90, 5.91 MPa, respectively. Statistical differences of the SBS existed between Group 1 and 2 (P < 0.05) and between Group 3 and 4 (P < 0.05). No difference was found between Group 1 and 3, or Group 2 and 4. CONCLUSION: Omission of the acid-etching step in rebonding orthodontic brackets may be adequate for the clinical requirement. No differences in SBS and ARI of the rebonded brackets were showed between CEP and SEP methods.

Analysis of facial bone wall dimensions and sagittal root position in the maxillary esthetic zone: a retrospective study using cone beam computed tomography.

PURPOSE: To determine the thickness of the facial bone wall and the sagittal angulation between the long axis of the teeth and the long axis of the associated alveolar bone in the maxillary esthetic zone using cone beam computed tomography (CBCT). MATERIALS AND METHODS: A retrospective radiographic study of CBCT images was conducted in 300 patients. The distance between the cementoenamel junction (CEJ) and the facial bone crest, the thickness of the facial bone wall (4 mm apical to the CEJ and midroot), and the sagittal angle between the long axis of teeth and the long axis of the respective alveolar bone were measured. Descriptive statistics and frequency analyses were performed. RESULTS: The sample included 133 men and 167 women (mean age, 36.9 years; range, 18 to 60 years). The distance between the CEJ and the facial bone crest varied between 0.1 and 4 mm and showed an overall tendency to increase with age. Almost 80% of anterior teeth and 40% of premolars exhibited a thin facial bone wall (< 1 mm), and nearly 30% of sites had a bone wall thinner than 0.5 mm. The sagittal angle at approximately 80% of central incisor and second premolar sites was < 20 degrees, but the angle at more than 40% of canine sites was ≥ 30 degrees. There was a significant decrease in facial bone wall thickness from premolars to anterior teeth. CONCLUSION: The facial bone wall in most maxillary anterior teeth was very thin. There was a substantial sagittal angulation between the long axes of teeth and those of their respective alveolar bone in most esthetic zone positions. CBCT analyses of the facial bone wall and the sagittal angle are recommended to ensure the most appropriate dental implant treatment approach.

Use of the versatile sternocleidomastoid flap in oral and maxillofacial surgery: our experience.

Our aim was to evaluate the reliability of sternocleidomastoid (SCM) flaps in the reconstruction of defects after oral and maxillofacial resections, and summarise the ways in which morbidity can be reduced. We retrospectively enrolled 65 patients who had malignant tumours resected, and assessed the postoperative viability of the SCM flap. All complications were recorded during a follow up period of 1-64 months. We also investigated the relation between recurrence in regional lymph nodes and their preoperative histological state. The conventional SCM flap, the split SCM flap with only the sternal head, and the SCM flap with a half-thickness clavicular graft, were used to repair different defects. No flaps necrosed completely, and in only 5 cases was there partial loss of the skin paddle. The skin paddle avulsed in 2 cases 2 patients developed wound infections. Only 9 patients developed complications (14%, 9/65). Use of the split SCM flap overcomes the problem of bulk. The combination of the SCM flap and clavicular bone enables early dental implantation. The SCM flap is convenient, reliable, and technically easy for the reconstruction of intraoral or mandibular tissue loss. Preservation of the branch of the superior thyroid artery and precise surgical technique contribute to a higher success rate.

[The application of intermaxillary traction titanium screw in complicated mandibular fracture].

PURPOSE: To assess the clinical effect of intermaxillary traction titanium screw on complicated mandibular fracture. METHODS: Fifty cases of complicated mandibular fracture received ten intermaxillary traction titanium screws and conducted intermaxillary fixation before operation; then the patients underwent open reduction and internal fixation; after operation intermaxillary traction was performed for 2-4 weeks. RESULTS: Fifty cases of complicated mandibular fracture displayed satisfied occlusion and bone union without major complications. CONCLUSIONS: The intermaxillary traction titanium screw could reduce the time of operation, and shows high efficiency in fixation of mandibular fracture.