A pilot study using machine learning methods about factors influencing prognosis of dental implants

PURPOSE: This study tried to find the most significant factors predicting implant prognosis using machine learning methods. MATERIALS AND METHODS: The data used in this study was based on a systematic search of chart files at Seoul National University Bundang Hospital for one year. In this period, oral and maxillofacial surgeons inserted 667 implants in 198 patients after consultation with a prosthodontist. The traditional statistical methods were inappropriate in this study, which analyzed the data of a small sample size to find a factor affecting the prognosis. The machine learning methods were used in this study, since these methods have analyzing power for a small sample size and are able to find a new factor that has been unknown to have an effect on the result. A decision tree model and a support vector machine were used for the analysis. RESULTS: The results identified mesio-distal position of the inserted implant as the most significant factor determining its prognosis. Both of the machine learning methods, the decision tree model and support vector machine, yielded the similar results. CONCLUSION: Dental clinicians should be careful in locating implants in the patient's mouths, especially mesio-distally, to minimize the negative complications against implant survival.

Peri-implant bone length changes and survival rates of implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height

PURPOSE: The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants. METHODS: Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The peri-implant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed. RESULTS: Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger. CONCLUSIONS: This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.

Evaluation on short term after hepatectomy for the patients with primary hepatocellular carcinoma / 中华外科杂志

<p><b>OBJECTIVE</b>To analyze the high risk factors for tumor recurrence in short term after hepatectomy for the patients with primary hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>Five hundreds and two patients with primary HCC underwent hepatectomy were included from January 1997 to December 2008. Among these patients, males were 419 cases and females were 83 cases. The age was 14 to 82 years (average age 54 years). The results of evaluation on 2 months after resection and tumor recurrence and survival were analyzed.</p><p><b>RESULTS</b>According to the operative and pathologic findings and the evaluation on 2 months after hepatectomy, the patients with vascular invasion, palliation resection, cutting edge pathologic residual tumor, lymph notes metastasis, serum AFP level continuing higher after resection or(and) positive TACE (tumor dyeing on TACE within 1 month and a deposit of lipiodol on CT scan) were high risk factors (high-risk group, 106 cases, 21.1%), the recurrence-free survival was 22%, 9% and 3% (1, 2 and 5 year) and overall survival was 52%, 25% and 8%. On the non-high risk group patients, the recurrence-free survival was 84%, 67%, 42% and 31% (1, 2, and 5 year) and overall survival was 97%, 85%, 56% and 35%. The bigger tumor, poor differentiation, tumor invading to liver capsule, satellite focus and TNM III-IV stage in high-risk groups were more significantly than that in non-high-risk groups.</p><p><b>CONCLUSION</b>The vascular invasion, palliation resection, cutting edge pathologic residual tumor, lymph notes metastasis, serum AFP level continuing higher or (and) positive TACE within 2 months after resection are high risk factors for HCC patients in short term after hepatectomy, which mean tumor remnant.</p>

Experimental study on monitoring gene expression by noninvasive method in rabbit VX2 liver tumor model / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the feasibility of monitoring therapeutic effect of adenovirus vector containing IL12-IRES-CKb gene on a rabbit VX2 liver tumor model by using phosphorous-31 magnetic resonance spectroscopy (31P MRS).</p><p><b>METHODS</b>A total of 18 healthy New Zealand White rabbits were used to generate animal models by implanting VX2 tumor chips into livers through laparotomy. Tumor-bearing animals were randomly divided into three groups and were injected with AdCMVIL12-IRES-CKb, AdCMV-Empty and saline respectively via ear veins. 31P MRS scan was performed after animals were fed with creatine solution for five days. Animals were euthanized thereafter and tumors were removed for pathological examination, immunohistochemistry (IHC) staining and protein analysis (Western blot).</p><p><b>RESULTS</b>The intrahepatic and seral expressions of creatine kinase (CKb) and IL-12 were detected only in AdCMVIL12-IRES-CKb group. Tumor diameters pre- and post- treatment in three groups were 1.63+/-0.04 vs 1.62+/-0.03 in AdCMVIL12-IRES-CKb group (P = 0.229), 1.59+/-0.05 vs 1.84+/-0.11 in AdCMV-Empty group (P = 0.003) and 1.60+/-0.02 vs 2.07+/-0.12 in saline group (P = 0.001), respectively. Pcr Changes between pre- and post- treatment among the three groups were compared (F = 6.235, P value is less than 0.05). PCr increased significantly in AdCMVIL12-IRES-CKb group as compared to AdCMV-Empty (P = 0.004) and saline group (P = 0.049), whereas no change found between AdCMV-Empty and saline group (P = 0.153).</p><p><b>CONCLUSION</b>31P MRS, an effective and non-invasive functional imaging method, can be used to monitor the therapeutic effect of adenovirus vector containing IL12-IRES-CKb gene on rabbit VX2 liver tumor model through detecting metabolic product of imaging reporter gene CKb (pCr).</p>

Prognostic value of E-cadherin, CD34 in the patients with hepatocellular carcinoma / 中华外科杂志

<p><b>OBJECTIVE</b>To study the expression of E-cadherin and CD34 in the tissues of hepatocellular carcinoma (HCC), to discuss the relationship between them and the clinical pathology and evaluate the prognosis of HCC patients.</p><p><b>METHODS</b>The expression of E-cadherin and CD34 in HCC tissues of 41 patients were examined by two-step methods of PV-6000 of immunohistochemistry. Clinical-pathological data, tumor recurrent rate and survival rate after hepatectomy were recorded and analyzed.</p><p><b>RESULTS</b>The positive expression rate was observed in 48.78% for E-cadherin and 100% for CD34. The decreased E-cadherin expression were significantly associated with larger tumor, the high-dangerous group with invasion and poor differentiation of HCC tissues (chi(2) = 4.1881, 4.8118, 6.2695, P < 0.05). In the group with negative-expression of E-cadherin, the percent of tumor recurrence within 2 years after hepatectomy was higher and the rate of 5 years survival was significantly lower than the positive-expressed group. A significant negative-correlation between the expression of CD34 and the patients' age and the invasion of tumor (t = 1.9371, 1.9010, P < 0.05) were found. There was no relationship between the expression of E-cadherin and CD34 in HCC tissues.</p><p><b>CONCLUSIONS</b>The patient with a negative-expression of E-cadherin in HCC tissues has a poor prognosis. No relationship between the expression of CD34 and tumor recurrence and patients' survival and no relationship between the expression of E-cadherin and CD34 was found.</p>