Comparison of the physical, thermal, and biological effects on implant bone site when using either zirconia or stainless-steel drill for implant bone site preparation.

BACKGROUND/PURPOSE: Zirconia has been a popular material in dental implantology with good biocompatibility. But few research focused on its application in implant drills. This study aimed to investigate the physical, thermal, and biological effects on using the zirconia and stainless-steel drills for implant bone site preparation. METHODS: We performed a series of experiments to evaluate the physical wearing properties of zirconia and stainless-steel drills of identical diameter and similar shape. During the implant site preparation thermal test, we subjected both drills onto a resin-embedded bone, utilizing a thermal couple device without irrigation. Moreover, we conducted a cell study by collecting bone cells in vivo while preparing the implant site with both tested drills. The cell activity was evaluated through cell proliferation colorimetric analysis (XTT) and alkaline phosphatase (ALP) activity measurements. RESULTS: The zirconia drill outperforms the stainless-steel drill in terms of requiring less force, maintaining stability over repeated cutting tests, and generating lower temperatures during drilling (stainless-steel drill: 45.48 ± 1.31 °C; zirconia-coated drill: 32.98 ± 1.21 °C, P = 0.000247). Meanwhile, both types of drills show similar results in XTT colorimetric analysis and ALP activity test. CONCLUSION: The thermal effect study is more favorable for using the zirconia drill than the stainless-steel drill for bone preparation. Cytological analysis indicate that the zirconia drill produces a similar impact on bone cells activity as the stainless-steel drill. Therefore, we conclude that the zirconia drills offer a good cutting effect similar to currently available stainless-steel drills in various aspects.

Significantly higher serum tumor marker levels in patients with oral submucous fibrosis.

BACKGROUND/PURPOSE: Our previous study showed that carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC-Ag), and ferritin are significantly higher in patients with oral potentially malignant disorders (OPMDs including oral leukoplakia, oral erythroleukoplakia, and oral verrucous hyperplasia) than in healthy controls (HCs). Oral submucous fibrosis (OSF) is also recognized as an OPMD. This study evaluated whether these three serum tumor marker levels were also significantly higher in OSF patients than in HCs. MATERIALS AND METHODS: The serum CEA, SCC-Ag, and ferritin levels in 41 OSF patients and 164 HCs were measured and compared. Patients with serum CEA level ≥3 ng/mL, SCC-Ag level ≥2 ng/mL, and ferritin level ≥250 ng/mL were scored as serum positive for CEA, SCC-Ag, and ferritin, respectively. RESULTS: We found significantly higher mean serum CEA, SCC-Ag, and ferritin levels in 41 OSF patients than in 164 HCs (all P-values < 0.05). Moreover, 41 OSF patients had significantly higher serum positive rates of CEA (39.0%), SCC-Ag (19.5%), and ferritin (53.7%) than 164 HCs (all P-values < 0.05). Of the 41 OSF patients, 26 (63.4%), 7 (17.1%), and 2 (4.9%) had serum positivities of one, two, or three tumor markers including CEA, SCC-Ag, and ferritin, respectively. CONCLUSION: There are significantly higher mean serum CEA, SCC-Ag, and ferritin levels and significantly higher serum positive rates of CEA, SCC-Ag, and ferritin in OSF patients than in HCs. The serum CEA, SCC-Ag, and ferritin levels may be served as tumor markers for evaluation of malignant potential of OSF lesions.

Higher serum homocysteine level and frequency of hyperhomocysteinemia in carcinoembryonic antigen-positive or squamous cell carcinoma-antigen-positive oral leukoplakia patients.

BACKGROUND/PURPOSE: Our previous study found significantly lower serum hematinic levels and higher serum homocysteine level as well as higher frequencies of serum hematinic deficiencies and hyperhomocysteinemia in oral leukoplakia (OL) patients than in healthy control subjects. This study evaluated whether carcinoembryonic antigen (CEA)-positive or squamous cell carcinoma-antigen (SCC-Ag)-positive OL patients had significantly lower serum hematinic levels and higher serum homocysteine level as well as significantly higher frequencies of hematinic deficiencies and hyperhomocysteinemia than CEA-negative or SCC-Ag-negative OL patients or healthy control subjects. METHODS: The complete blood count, serum iron, vitamin B12, folic acid, and homocysteine levels in 184 OL patients including 85 CEA-positive, 99 CEA-negative, 25 SCC-Ag-positive, and 159 SCC-Ag-negative OL patients and in 184 age- and sex-matched healthy control subjects were measured and compared. RESULTS: We found that the 85 CEA-positive or 25 SCC-Ag-positive OL patients had a significantly lower mean serum folic acid level and a significantly higher mean serum homocysteine level as well as significantly higher frequencies of serum folic acid deficiency and hyperhomocysteinemia than 184 healthy control subjects. Moreover, the 25 SCC-Ag-positive OL patients had a significantly higher mean serum homocysteine level than the 159 SCC-Ag-negative OL patients. The 85 CEA-positive OL patients had a higher mean serum homocysteine level and a higher frequency of hyperhomocysteinemia than 99 CEA-negative OL patients (marginally significant, P = 0.060). CONCLUSION: CEA-positive or SCC-Ag-positive OL patients tend to have a higher mean serum homocysteine level and a higher frequency of hyperhomocysteinemia than CEA-negative or SCC-Ag-negative OL patients, respectively.

Serum levels and positive rates of tumor biomarkers in oral precancer patients.

BACKGROUND/PURPOSE: Several previous studies have reported higher serum tumor marker levels in patients with oral or head and neck squamous cell carcinomas. This study evaluated whether 232 patients with oral precancerous lesions (oral precancer patients) had significantly higher serum carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC-Ag), and ferritin levels than healthy control subjects. METHODS: The serum CEA, SCC-Ag, and ferritin levels in 232 oral precancer patients and 187 healthy control subjects were measured and compared. Patients with serum CEA level ≥3 ng/mL, SCC-Ag level ≥2 ng/mL, and ferritin level ≥250 ng/mL were scored as serum positive for CEA, SCC-Ag, and ferritin, respectively. RESULTS: We found significantly higher mean serum CEA, SCC-Ag, and ferritin levels in 232 oral precancer patients than in 187 healthy control subjects (all P-values < 0.05). Moreover, 232 oral precancer patients had significantly higher serum positive rates of CEA (47.4%), SCC-Ag (13.8%), and ferritin (52.2%) than 187 healthy control subjects (all P-values < 0.05). Of the 232 oral precancer patients, 121 (52.1%), 56 (24.1%), and 10 (4.3%) had serum positivities of one, two, or three tumor markers including CEA, SCC-Ag, and ferritin, respectively. CONCLUSION: There are significantly higher mean serum CEA, SCC-Ag, and ferritin levels and significantly higher serum positive rates of CEA, SCC-Ag, and ferritin in oral precancer patients than in healthy control subjects. The serum CEA, SCC-Ag, and ferritin levels are of diagnostic value and may be potential tumor markers for the screening of oral precancer patients.

Differences in the biomechanical behaviors of natural teeth and dental implants.

OBJECTIVE: The lack of a PDL, which acts as an energy absorber, is a contributor to implants' early failure; however, these discrepancies are not well understood because of limited in vivo research. This study investigated the discrepancy in biomechanical behaviors between natural teeth and dental implants by detecting micro-movements in vivo. METHODS: We designed a device that could measure precisely mechanical behaviors such as creep, stress relaxation, and hysteresis by using load-control displacement on teeth and implants. We also compared energy dissipation between natural teeth and dental implants by subtracting the area of the hysteresis loop of natural teeth from that of dental implants. RESULTS: Biphasic curves with an initial phase of rapid response and a subsequent phase of slow response were confirmed in creep and stress relaxation curves for the load-time relationship in natural teeth. By contrast, the behavior of creep or stress relaxation was less prominent when the dental implants were tested. We observed that the periodontal ligament under an axial intrusive load of 300g in a loading rate 3g/s could dissipate the energy of 7.35±1.18×10-2 mJ, approximately 50 times that of the dental implants (1.47±1.22×10-3) with statistically significant (p<0.05). SIGNIFICANCE: We confirmed natural teeth could achieve greater energy dissipation compared to dental implants, which owe to that natural teeth exhibited fluid and viscoelastic properties.

Neutralized Dicalcium Phosphate and Hydroxyapatite Biphasic Bioceramics Promote Bone Regeneration in Critical Peri-Implant Bone Defects.

The aim of this study was to evaluate the efficacy of bone regeneration in developed bioceramics composed of dicalcium phosphate and hydroxyapatite (DCP/HA). Critical bony defects were prepared in mandibles of beagles. Defects were grafted using DCP/HA or collagen-enhanced particulate biphasic calcium phosphate (TCP/HA/Col), in addition to a control group without grafting. To assess the efficacy of new bone formation, implant stability quotient (ISQ) values, serial bone labeling, and radiographic and histological percentage of marginal bone coverage (PMBC) were carefully evaluated four, eight, and 12 weeks after surgery. Statistically significant differences among the groups were observed in the histological PMBC after four weeks. The DCP/HA group consistently exhibited significantly higher ISQ values and radiographic and histological PMCB eight and 12 weeks after surgery. At 12 weeks, the histological PMBC of DCP/HA (72.25% ± 2.99%) was higher than that in the TCP/HA/Col (62.61% ± 1.52%) and control groups (30.64% ± 2.57%). After rigorously evaluating the healing of biphasic DCP/HA bioceramics with a critical size peri-implant model with serial bone labeling, we confirmed that neutralized bioceramics exhibiting optimal compression strength and biphasic properties show promising efficacy in fast bone formation and high marginal bone coverage in peri-implant bone defects.

Clinical outcomes of oral cancer patients who survive for more than 5 years in Taiwan.

BACKGROUND/PURPOSE: Oral cancer patients who survive for more than 5 years are supposed to have a reduced local cancer recurrence rate and survive longer. This study evaluated whether oral cancer patients who survived for more than 5 years might have reduced rates of local cancer recurrence, development of the second or third primary oral cancer, or the late regional cervical lymph node metastasis. METHODS: This study analyzed the clinical outcomes of 127 oral cancer patients (101 men and 26 women; mean age, 50.8 ± 12.1 years) who survived for more than 5 years after proper treatments of the initial primary oral cancers. RESULTS: The 127 primary oral cancers included 117 squamous cell carcinomas (SCCs), 7 mucoepidermoid carcinomas, and 3 others. Of the 127 oral cancer patients who survived for more than 5 years, 47 survived for 5-9 years, 45 for 10-14 years, 22 for 15-19 years, 10 for 20-24 years, two for 25-29 years, and one for 30 years. Ten patients had local cancer recurrence 5.4 years-13.7 years, 12 patients had a second or a third primary oral cancer 3.6 years-17.2 years, and one mucoepidermoid carcinoma patient had a late regional cervical lymph node metastasis 11.9 years after total excision of the initial primary oral cancers. CONCLUSION: Oral cancer patients who survive for more than 5 years may still have local cancer recurrence, the second or third primary oral cancer, or the late regional cervical lymph node metastasis but with a reduced rate.