• Restorative Dentistry and Endodontics
• /
• v.34 no.4
• /
• pp.346-349
• /
• 2009

Mandibular second molars have many variations in canal configuration. Technical modifications in cleaning, shaping and obturation are required. The purpose of this study was to investigate the root canal anatomy of mandibular second molars. 86 teeth of 85 patients were accessed and evaluated with taking radiographs for working length determination. 27 teeth(31.4%) had C-shaped canals, 43 teeth(50%) had 3 canals, 11 teeth(12.7%) had 4 canals, 5 teeth(5.8%) had 2 canals. Incidence of C-shaped canal was 31.7% in male and 31.1% in female. 30.9% of left mandibular second molar and 31.8% of right mandibular second molar showed C-shaped canals.

• Imaging Science in Dentistry
• /
• v.36 no.4
• /
• pp.183-188
• /
• 2006

Purpose: The purpose of this research was to study bone changes after bilateral sagittal split osteotomy through fractal analysis and measurement of mandibular cortical thickness. Materials and Methods: This study included twenty-two prognathic patients who underwent bilateral sagittal split osteotomy. Panoramic radiographs of these patients were taken immediately before operation and at 1 month, 6 months, and 12 months postoperatively. The fractal dimension was measured by the box-counting method in the region of interest centered on both the basal and interdental bones between the first and second mandibular molars. Measurements of mandibular cortical thickness were taken both in the area between the first and second mandibular molars and at the osteotomy site. Changes of fractal dimension and cortical thickness over four stages were statistically analyzed. Results: The fractal dimension of the mandibular basal bone before surgery and after 1 month, 6 months and 12 months were $1.4099{\pm}0.0657,\;1.382{\pm}0.0595,\;1.2995{\pm}0.0949,\;and\;1.4166{\pm}0.0676$, respectively (Repeated-measures ANOVA, P<0.001). However, no statistically significant differences were noted in interdental fractal dimensions among the four stages. Mandibular cortical thickness between the first and second mandibular molars before operation and after 1 month, 6 months and 12 months was $3.74{\pm}0.48mm,\;3.63{\pm}0.47mm,\;3.41{\pm}0.61mm\;and\;3.55{\pm}0.66mm$ (P<0.01), respectively. Mandibular cortical thickness at the osteotomy site at each of the four stages was $3.22{\pm}0.44mm,\;2.87{\pm}0.59mm,\;2.37{\pm}0.61mm\;and\;2.64{\pm}0.62mm$, respectively (P<0.001). Conclusion: This study suggests that the mandibular tissue continued decreasing for 6 months postoperatively and then increased over the subsequent 6 months.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.20 no.2
• /
• pp.143-150
• /
• 2004

Endosseous implants have been used to provide anchorage control in orthodontic treatment without the need for special patient cooperation. However these implants have limitation like space requirement, cost, equipments. Recently titanium micro-implant for orthodontic anchorage was introduced. Micro-implants are small enough to place in any area of the alveolar bone, easy to implant and remove, and inexpensive. In addition, orthodontic force application can begin almost immediately after implantation. The mandibular first, maxillary first, mandibula second, and maxillary second molars were the four most commonly missing teeth in adult sample. In case of posterior molar teeth missing, deflective contacts in any position, over time, has produced pathologic change of occlusal scheme because of extrusion of opposing teeth. This case had interocclusal space deficiency by mandibular right molars missing over time. The micro-implants had been used for intrusion of maxillary right molars for interocclusal space. The micro-implant would be absolute anchorage for orthodontic movement. Therefore, the micro-implant would be effective method for correction of occlusal plane.

• Journal of Technologic Dentistry
• /
• v.11 no.1
• /
• pp.65-70
• /
• 1989

The development of the lobe pattern in the human dentition plays a part in the form and function of each individual teeth. In order to determin the morphological categories used to describe the occlusal surfaces of the maxillary and mandibular molars, the variation of the developmental grooves which separate each lobe in the molars was examined and analysed. The obtained conclusions were as follow. 1. Most of the maxillary first molars with more distinct and more developmental grooves than the other molars but in most cases of the third molar, a heart-shaped outline due to poorly developed or abscent distolingual cusp was most frequent and in this case the third molar had the 3 cusps separated by the central developmental groove and the buccal developmental groove. 2. In most cases, the mandibular first molar had the 5-cusp type that the groove patter resembles a Y, the second molar the 4-cusp type arranged in such a way that the buccal and lingual developmental grooves meet the central developmental groove at right angle on the occlusal surface and many instances of the mandibular third molars had the 5-cusp thpe with a+groove pattern which separatess the mesiolingual cusp from the distobuccal cusp and the 4-cusp type with a+groove pattern. 3. The maxillary and mandibular third molar were most variable in the developmental groove.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.22 no.5
• /
• pp.339-348
• /
• 2022

Background: To compare the anesthetic efficacy of supplemental buccal infiltration (BI) (1.7 ml) versus intraligamentary (IL) injection containing 0.4 ml of 4% articaine with 1:100.000 epinephrine after an inferior alveolar nerve block (IANB) with 1.7 ml 2% lidocaine in the first and second mandibular molars diagnosed with irreversible pulpitis (IP). Methods: One hundred subjects diagnosed with IP of either the mandibular first (n = 50) or second molars (n = 50) and failed profound anesthesia following an IANB were selected. They randomly received either the IL or BI techniques of anesthesia. Pain scores on a 170 mm Heft-Parker visual analog scale were recorded initially, before, and during supplemental injections. Furthermore, pulse rate was measured before and after each supplemental injection. During the access cavity preparation and initial filing, no or mild pain was assumed to indicate anesthetic success. The chi-square test, Mann-Whitney U test, and independent samples t-test were used for the analyses. Results: The overall success rates were 80% in the IL group and 74% in the BI group, with no significant difference (P = 0.63). In the first molars, there was no significant difference between the two techniques (P = 0.088). In the second molars, IL injection resulted in a significantly higher success rate (P = 0.017) than BI. IL injection was statistically more successful (P = 0.034) in the second molars (92%) than in the first molars (68%). However, BI was significantly more successful (P = 0.047) in the first molars (88%) than in the second molars (64%). The mean pulse rate increase was significantly higher in the IL group than in the BI group (P < 0.001). Conclusions: Both the IL and BI techniques were advantageous when used as supplemental injections. However, more favorable outcomes were observed when the second molars received IL injection and the first molars received BI.

• Journal of Periodontal and Implant Science
• /
• v.32 no.1
• /
• pp.61-68
• /
• 2002

The objective of this study was to determine the incidence and distribution of root fusion as well as its sexlinkage in maxillary and mandibular molars. One hundred fifty patients who had eight maxillary and mandibular molars (third molars excluded) were consecutively selected for the study subjects. The subjects provided a total of 1200 molars, i.e., 600 maxillary and 600 mandibular molars. A decision about root fusion was made on the radiographic examination. If a molar had one root and/or roots fused at any part in the root surface, it was considered as having root fusion. The results showed that : (1) 14.1 % of the maxillary molars and 5.8 % of the mandibular molars had a fused root, (2) the prevalence of root fusion in the male was 33 % and 56.4 % in the female, (3) 60 % in the male and 48.8 % in the female had bilaterally paired root fusion, (4) the root fusion was most frequently observed in the maxillary second molar position, but none in the mandibular first position in this study. Within limitations of this study, it can be concluded that, in management of molars with a furcation problem, treatment options such as hemisection and root amputation should be chosen after careful evaluation of root fusion. Further studies are needed to investigate a possible relationship between root fusion and periodontal disease progression.

• Journal of Periodontal and Implant Science
• /
• v.36 no.2
• /
• pp.489-502
• /
• 2006

The purpose of this study was to determine the relationship between the third molar and periodontal status of the adjacent second molar. Fifty patients who had four maxillary and mandibular second molars were consecutively selected for the study subjects. The subjects provided a total of 200 molars, i. e., 100 maxillary and 100 mandibular molars, and classified the groups as follows; third molars that are normally erupted are control group, that are impacted are test 1 group, that are simply extracted are test 2 group, that are surgically extracted are test 3 group. Probing depth, plaque index, gingival index and mobility were measured. The results were as follows. 1. In mesial probing depth, there was no significantly difference. In distal probing depth, there was a significantly difference between control group and test 1 & 3 group in maxilla and between control & test 2 group and test 1& 3 group in mandible(p<0.05). 2. In buccal probing depth, there was a significantly difference between test 2 group and test 3 group in mandible. In lingual probing depth, there was a significantly difference between control group and test 1 & 3 group in mandible(p<0.05). 3. In plaque index, there was a significantly difference between test 1 group and test 2 group in maxilla, between test 1 group and control & test 2 group in mandible(p<0.05). 4. In gingival index, there was a significantly difference between control group and test 1 & 3 group in mandible. In mobility, there was no significantly difference(p<0.05). As a result of this study, the second molars adjacent to the third molars that are impacted or surgically extracted had poor prognosis, so impacted third molars should be extracted in early time and the second molars are actively treated for periodontal health.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.28 no.5
• /
• pp.341-347
• /
• 2002

This study was designed to determine the location of the mandibular canal on lower molar areas. Thirty-three patients were examined with multi-planar reformatted CT scan($Dentascan^{(R)}$). Three kinds of measurements were performed. The first was the distances between the upper border of the mandibular canal and the root apices of the first and second molars, the second was the distance between the cortical plate of the mandible and mandibular canal, and the last was the location of the mandibular canal in the buccolingual plane. The obtained results are as follows 1. The distance between the root apices of lower molars and the superior border of mandibular canal was largest at the mesial root of the first molar, and shortest at the distal root of the second molar(p<0.05). 2. The longest distance between the outer surface of the buccal cortical plate of the mandible and mandibular canal was measured from the distal root of the second molar, and this distance decrease gradually mesially(p<0.05). 3. The distance between the mandibular base and inferior border of mandibular canal was longest at the distal root of the second molar, and shortest at the mesial root of the first molar(p<0.05). 4. The location of mandibular canal was lingually positioned in relation to the axis of teeth and alveolar ridge in molar areas.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.48 no.1
• /
• pp.63-67
• /
• 2022

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.1 no.1
• /
• pp.13-19
• /
• 1971

The author has studied on 910 roentgenograms of lower second molars, which were taken by intraoral technic, and obtained the following results. 1. The development of crown of lower second molars was completed 8.25 years. 2. The formation of mesial and distal roots in full length on lower second molars was completed as follows: a. mesial roots 15. 07 years b. distal roots 15. 53 years 3. The formation of apical foramina of mesial and distal roots of lower second molars was closured as follows: a. apical foramen of mesial root 18.00 years b. apical foramen of distal root 18.79 years 4. As a general rule, the mesial roots were developed more earlier than distal roots.