ABSTRACT
Objective To study the clinical value of Time self -locking brackets in relieving the changes of dental arch and tooth morphology after maxillary dentition crowding .Methods From January 2015 to December 2015,80 patients with maxillary dentition in Rizhao Central Hospital were randomly divided into two groups according to the random number method ,with 40 cases in each group.The control group was treated with traditional MBT straight wire brackets (3M Company).The observation group was treated with Time self -locking brackets.And the width of the two groups was compared before and after the intervention.The treatment time and the incidence of complications during the treatment were observed in the two groups.Results After intervention,the width of canine and the length of long,middle bow in the observation group were significantly better than those in the control group ( t＝7.901, 29.820,15.652,all P＜0.05).The treatment time of the observation group was significantly shorter than that of the control group (t＝41.716,P＝0.000＜0.05).The incidence rate of bleeding ,swelling and loosening in the observa-tion group was significantly lower than that in the control group (χ2＝5.212,P＜0.05).The bracket shedding rate in the observation group was significantly lower than that in the control group ( χ2＝5.600,P＜0.05).Conclusion Time self-locking brackets is effective in the treatment of maxillary dentition crowding.The method has the advantages of high effect,simple clinical treatment ,less complication and low shedding rate during treatment.
ABSTRACT
PURPOSE: The aim of this study was to investigate dental arch dimensions and to classify arch shape in Korean young adults. MATERIALS AND METHODS: The sample included 50 Koreans with age ranging from 24 to 32 years. Maxillary and mandibular casts were fabricated using irreversible hydrocolloid and type III dental stones. Incisor-canine distance, incisor-1(st) molar distance, incisor-2(nd) molar distance, intercanine distance, inter-1(st) molar distance, and inter-2(nd) molar distance in both the maxillary and mandibular arch were measured using a three-dimensional measuring device. The dental arch was classified into three groups using five ratios from the measured values by the K-means clustering method. The data were analyzed with one-way analysis of variance. RESULTS: Arch lengths (IM2D, incisal-2(nd) molar distance) were 44.13 mm in the maxilla and 40.40 mm in the mandible. Arch widths (M2W, inter 2(nd) molar width) were 64.12 mm in the maxilla and 56.37 mm in the mandible. Distribution of the dental arch form was mostly ovoid shape (maxilla 52% and mandible 56%), followed by the V-shape and the U-shape. The arch width for the U-shape was broader than for the other forms. CONCLUSION: This study establishes new reference data for dental arch dimensions for young Korean adults. The most common arch form is the ovoid type in the maxilla and mandible of Koreans. Clinicians should be aware of these references and classify arch type before and during their dental treatment for effective and harmonized results in Koreans.
Subject(s)
Adult , Humans , Young Adult , Colloids , Dental Arch , Mandible , Maxilla , Methods , MolarABSTRACT
OBJECTIVE: The aim of this laboratory study is to evaluate the influence of the shape and the length limitation of superelastic nickel-titanium (NiTi) archwires on lower incisors inclination during alignment and leveling. METHODS: Metal teeth mounted on a typodont articulator device were used to simulate a malocclusion of the mandibular arch (-3.5 mm model discrepancy). Three different shapes (Standard, Accuform and Ideal) of superelastic NiTi archwires (Sentalloy, GAC, USA) were tested. Specimens were divided in two groups: Group I, with no limitation of the archwire length; and Group II, with distal limitation. Each group had thirty specimens divided into three subgroups differentiated by the archwire shape. All groups used round wires with diameters of 0.014-in, 0.016-in, 0.018-in and 0.020-in. The recording of all intervals was accomplished using standardized digital photographs with orthogonal norm in relation to median sagittal plane. The buccolingual inclination of the incisor was registered using photographs and software CorelDraw. RESULTS: The results were obtained using ANOVA and Tukey's test at a significant level of 5%. The inclination of the lower incisor increased in both groups and subgroups. The shape of the archwire had statistically significant influence only in Group I - Standard (11.76º), Ideal (5.88º) and Accuform (1.93º). Analyzing the influence of the length limitation, despite the mean incisor tipping in Group II (3.91º) had been smaller than Group I (6.52º), no statistically significant difference was found, except for Standard, 3.89º with limitation and 11.76º without limitation. The greatest incisor tipping occurred with the 0.014-in archwires.
ABSTRACT
OBJECTIVE: To determine and compare the frequency distribution of various arch shapes in ethnic Malays and Malaysian Aborigines in Peninsular Malaysia and to investigate the morphological differences of arch form between these two ethnic groups. METHODS: We examined 120 ethnic Malay study models (60 maxillary, 60 mandibular) and 129 Malaysian Aboriginal study models (66 maxillary, 63 mandibular). We marked 18 buccal tips and incisor line angles on each model, and digitized them using 2-dimensional coordinate system. Dental arches were classified as square, ovoid, or tapered by printing the scanned images and superimposing Orthoform arch templates on them. RESULTS: The most common maxillary arch shape in both ethnic groups was ovoid, as was the most common mandibular arch shape among ethnic Malay females. The rarest arch shape was square. Chi-square tests, indicated that only the distribution of the mandibular arch shape was significantly different between groups (p = 0.040). However, when compared using independent t-tests, there was no difference in the mean value of arch width between groups. Arch shape distribution was not different between genders of either ethnic group, except for the mandibular arch of ethnic Malays. CONCLUSIONS: Ethnic Malays and Malaysian Aborigines have similar dental arch dimensions and shapes.