Ming-Kuang Guo

Application of Ni-Ti Rotary Files for Pulpectomy in Primary Molars

Nickel-titanium (Ni-Ti) instruments are widely used in adult endodontics as an efficient technique, but are rarely used for endodontic treatment for primary molars. To explore the feasibility of using Ni-Ti rotary instruments for root canal preparation in primary molars, 51 primary molars with intact root apex in 22 children, who ranged in age from 3.2 years to 7.7 years, were treated. A modified protocol for ProTaper(superscript ®) Ni-Ti rotary files using only two instruments (SX and S2) was used for root canal preparation, and canals were filled with a calcium hydroxide-iodoform paste. All teeth were restored with stainless steel crowns. Postoperative radiographs were taken immediately following treatment and at 3-month intervals. Success or failure was assessed based on clinical and radiographic criteria. We found that the success rate of endodontic treatment for primary molars using Ni-Ti instrument for root canal preparation was 95% at the 12-month recall examination. We conclude that with the modified protocol, ProTaper(superscript ®) Ni-Ti rotary files can be safely and efficiently applied for root canal preparation in primary molars.

Role of ALK5/Smad2/3 and MEK1/ERK Signaling in Transforming Growth Factor Beta 1–modulated Growth, Collagen Turnover, and Differentiation of Stem Cells from Apical Papilla of Human Tooth

INTRODUCTION Transforming growth factor β1 (TGF-β1) plays an important role in cell proliferation, matrix formation, and odontogenesis. This study investigated the effects of TGF-β1 on stem cells from apical papilla (SCAPs) and its signaling by MEK/ERK and Smad2. METHODS SCAPs were exposed to TGF-β1 with/without pretreatment and coincubation by SB431542 (an ALK5/Smad 2/3 inhibitor) or U0126 (a MEK/ERK inhibitor). Cell growth was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide assay or direct counting of viable cells. Collagen content was determined by using the Sircol collagen assay (Biocolor Ltd, Newtownabbey, Northern Ireland). Cell differentiation was evaluated by measuring alkaline phosphatase (ALP) activity. Smad2 and ERK1/2 phosphorylation was analyzed by Western blotting or PathScan phospho-enzyme-linked immunosorbent assay (Cell Signaling Technology Inc, Danvers, MA). RESULTS TGF-β1 stimulated the growth and collagen content of cultured SCAPs. TGF-β1 stimulated ERK1/2 and Smad2 phosphorylation within 60 minutes of exposure. Pretreatment by U0126 and SB431542 effectively prevented the TGF-β1-induced cell growth and collagen content in SCAPs. TGF-β1 stimulated ALP activity at lower concentrations (0.1-1 ng/mL) but down-regulated ALP at higher concentrations (>5 ng/mL). U0126 prevented 0.5 ng/mL TGF-β1-induced ALP activity but showed little effect on 10 ng/mL TGF-β1-induced decline of ALP in SCAPs. Interestingly, SB431542 attenuated both the stimulatory and inhibitory effects on ALP by TGF-β1. CONCLUSIONS TGF-β1 may affect the proliferation, collagen turnover, and differentiation of SCAPs via differential activation of ALK5/Smad2 and MEK/ERK signaling. These results highlight the future use of TGF-β1 and SCAP for engineering of pulpal regeneration and apexogenesis.

Dental Anomalies in Two Patients with Incontinentia Pigmenti

Incontinentia pigmenti (IP) is a rare X-linked dominant inherited disorder which has a variety of ectodermal aberrations. Skin hyperpigmentation is the most characteristic feature of IP. However, extracutaneous anomalies involving dentition, hair, eyes, and central nervous system are also found. The dental anomalies reported include peg-shaped or malformed teeth, hypodontia, delayed eruption, and impacted tooth. This report describes the dental anomalies in 2 IP patients who had the characteristic features of skin hyperpigmentation. One was a 13-year-old girl who had slender cone-shaped permanent anterior teeth, hypodontia, and delayed eruption of teeth which are characteristic dental anomalies in an IP patient. The other was a 10-year-old girl who only had 2 tulip-shaped maxillary permanent central incisors with shorter tapering roots but no congenital missing teeth or delayed eruption of teeth. Our findings suggest that IP may present a broad variation of dental anomalies individually. However, the characteristic finding of permanent anterior teeth with a longer crown and a shorter root found in both of our IP patients may be worthy of consideration in the differential diagnosis of IP.

An in vitro study on restoring bond strength of a GIC to saliva contaminated enamel under unrinse condition.

OBJECTIVES This study attempted to find a method of restoring the tensile bond strength of glass ionomer cement (GIC) to saliva contaminated enamel under unrinse condition. METHODS One hundred and thirty human non-carious permanent teeth were divided into two major groups. Either treatment with air drying, acetone, polyacrylic acid, maleic acid, tartaric acid, Scotchbond primer or no treatment at all was applied to both clean and saliva contaminated enamel surfaces prior to GIC placement. Samples were debonded in tension after 7 days of storage in water using a universal testing machine. Statistical analysis was performed using one-way ANOVA, Tukeys studentized range test and Wilcoxons rank sums test to determine the significance of the difference of tensile bond strengths within and between the two major groups. RESULTS Bond strength of GIC to clean enamel was 2.46+/-0.79 MPa while the bond strength of GIC to wet contaminated enamel was significantly reduced to 1.28+/-0.32 MPa (p<0.01). However, the bond strengths were restored when the contaminated enamel surfaces were air-dried (2.19+/-0.38 MPa) or applied with either maleic acid (2.80+/-0.63 MPa) or Scotchbond primer (2.13+/-0.65 MPa) before placing GIC over the enamels. CONCLUSIONS Air drying, or application of maleic acid or Scotchbond primer to the contaminated enamel without rinsing prior to GIC placement can restore the tensile bond strength to a level similar to that of non-contaminated control.

Dental Treatment of Patients with Hemophilia A: A Case Report

Hemophilia A is a congenital bleeding disorder caused by deficiency of factor VIII. These patients may experience prolonged bleeding upon trauma or surgical procedures. This case is a 5-year-old boy with severe type of hemophilia A seeking for dental treatment. With pre-operative factor replacement, he received full-mouth dental treatment without any unexpected bleeding episode. After chair-side oral hygiene instruction and dietary counseling, he maintained fair oral hygiene and dental health during 3-month follow-ups. It is shown that with appropriate treatment planning, severe type hemophilic patients can safely receive dental treatment without unfavorable outcomes.

Management of a Traumatic Injured Immature Maxillary Incisor by Cvek Pulpotomy : A Case Report

Cvek pulpotomy is a conservative vital pulp therapy that consists of removing approximately 2 mm inflamed coronal pulp and placing biocompatible material over the underlying pulp tissue. This technique is suitable for treating traumatic injured immature teeth with pulp exposure. This case report presents a 9 year-old boy suffered from complicated crown fracture on tooth #11 two days ago and received Cvek pulpotomy with MTA dressing. Two mm of coronal pulp tissue from the exposure site was surgically removed, followed with normal saline irrigation and 2.5% NaOCl cotton pellets hemostais for 1 minute. Gray MTA was placed over the pulp stump, and GIC was then used for coronal seal. After 28 months follow-up, clinically no symptoms and signs were observed. Periapical x-ray revealed complete root formation, and electric pulp test (EPT) showed positive response.

Dental Treatment of Wolf-Hirschhorn Syndrome under General Anesthesia-A Case Report

Wolf-Hirschhorn syndrome (WHS) is a congenital anomaly caused by deletion of chromosomal region 4p16.3. It is characterized by delay pre- and post-natal development, intellectual disability, and epilepsy. Various dentooro-facial abnormalities have been described in previous literatures. This case report presents a 7-year-1-month old boy with WHS, who presented typical systemic and craniofacial features. Multiple caries were treated under general anesthesia because patient was unable to cooperate in outpatient setting. Careful pre-anesthetic evaluation and planning is essential to avoid possible risk of difficult airway and malignant hyperthermia which are life-threatening. Oral hygiene instruction and dietary counseling for selecting appropriate foodstuff were advised and emphasized to the parents. Regular recall appointments were arranged at 3-month intervals.

Dental Considerations for Patient with Type 1 Diabetes Mellitus-A Case Report

Type 1 diabetes mellitus (DM) is characterized by insulin deficiency, hence resulting in hyperglycemia. The phenotype of insulin deficiency mostly results from autoimmune beta cell destruction. Blood sugar level of type 1 DM can only be controlled by insulin injection. Patient with type 1 DM is at risk of acute complications such as diabetic hypoglycemia or diabetic ketoacidosis, other chronic and oral complications were also stated in previous literature. This case report presents a 5-year-old boy with type 1 DM, with relatively well controlled blood sugar. However, some precautions and considerations should be taken for the safety of life for this patient during dental treatment. Multiple caries were treated in clinic. Oral hygiene instruction and dietary counseling had been emphasized. Regular recall appointments were arranged at 3 months intervals.

β-型地中海貧血之口腔顏面部徵狀及牙科治療－病例報告

Thalassemias are hereditary hemolytic anemia diseases, among which β-thalassemia major is the most severe type. This case is a 2-year-11-month old girl with β-thalassemia major who presented typical systemic feature, but without significant typical craniofacial features including chipmunk face, severe maxillary protrusion, upper lip retraction, anterior teeth protrusion, interdental spaces, large and varied degrees of malocclusion. With proper behavior management, carious teeth had received pulpal therapy and stainless steel crown restorations. Severe carious upper anterior teeth were extracted and followed with removable denture replacement. The dental treatments were scheduled and proceeded right after her regular blood transfusions. Oral hygiene instruction and practice, dietary consultation and periodic examination have been emphasized and advised. After 1 years follow-up, all remaining teeth remained free from signs and symptoms. The removable denture functioned well. β-thalassemia major patients need prudential planning before proceeding dental treatment.

Furcation Perforation Treated with Mineral Trioxide Aggregate in a Primary Molar: Results after 15 Months

Furcation perforation is an undesirable situation in primary teeth, and it may result in periodontal destruction and early shedding. Mineral trioxide aggregate (MTA) has been used in repairing of root perforations and furcation perforations in permanent teeth, but rarely used in primary teeth. A 4 years 7 months-old boy was referred to our hospital for the treatment of persistent buccal abscess over his primary mandibular left secondary molar. The periapical x-ray and clinical examinations showed furcation perforation on the tooth. After management with root canal treatment, MTA was placed over the perforation site and the tooth was then restored with stainless steel crown. The tooth was asymptomatic and the radiolucent furcal lesion subsided following the treatment. After 15-month follow-up, the tooth remained asymptomatic and the furcal crestal bone healed. Therefore, MTA may be suggested as a suitable material for the repair of furcation perforation in primary molar teeth.