A Case Report of Kissing Molars Class II

Kissing molars (KMs) is a condition of occlusal molar surfaces in a single follicular space with roots extending in opposite directions. Here, we have reported a case of KMs in a 58-year-old woman. The patient complained of pain in the right mandibular molar region and was diagnosed with KMs consisting of the right mandibular second and third molars. Because of the patient’s pain having subsided at the time of the visit and her unwillingness to undergo tooth extraction, the patient was followed up. KMs is classified into three classes (I-III) and is either true-KMs or pseudo-KMs and presents with or without cystic variants of dental follicles. The presents as true-KMs class II without a cystic variant. With reference to the literature and based on our analysis, the mean age of patients affected by this specific case of KMs is 31.7 years and unilateral KMs is relatively more common (85.7%). Histopathological findings of dentigerous cysts are more often indicated (42.9%). The treatment policy for KMs should therefore be based on the classification of KMs. Importantly, the focus should be on preserving the first and second molars as much as possible. The treatment approach, such as the employment of surgical removal or orthodontics, should be determined by considering the associated factors such as the crowns, tissues, and age of the patient.

Two-stage extraction by partial grinding of impacted mandibular third molar in close proximity to the inferior alveolar nerve

BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.

Ectopic Molar Pregnancy with Coexistent Normal Intrauterine Pregnancy: A Report of an Unusual Diagnosis managed in Yaoundé Gyneco-Obstetric and Pediatric Hospital, Cameroon

Background: Heterotopic pregnancy is a very rare event in a natural cycle. Its incidence is rising mostly due to induction of ovulation or Assisted Reproductive Technique. Most ectopic in heterotopic pregnancies are localized in the fallopian tubes. The occurrence of molar tubal ectopic pregnancy coexisting with intrauterine pregnancy is uncommon and consequently not often considered a diagnostic possibility. Case Report: We report the case of a 25-year-old woman, gravida 4 para 1, who complained of vaginal spotting and lower abdominal pain after 6 weeks of amenorrhea following clomiphene citrate ovarian stimulation. Transvaginal Ultrasonography revealed an intrauterine pregnancy and an unruptured left tubal ectopic pregnancy. She underwent successful laparoscopic salpingectomy while the intra-uterine pregnancy was allowed to continue. The ectopic pregnancy tissue histology reported an ectopic partial molar pregnancy. She subsequently had a normal vaginal delivery at 39 weeks and 3 days and her follow-up was uneventful. Conclusion: Heterotopic pregnancy is a rare but life-threatening condition. It should be suspected in a pregnant woman with a risk factor of multiple gestations who presents vaginal bleeding and lower abdominal pain in the context of early pregnancy. Laparoscopic surgery is effective for confirming the diagnosis and treating the ectopic component. Routine histological examination of tubal specimens must be taken very seriously because some findings like molar pregnancies may require specific management.

Five-year outcomes of immediate implant placement for mandibular molars with and without chronic apical periodontitis:A retrospective study

BACKGROUND Most physicians consider molars with chronic apical periodontitis(CAP)lesions as contraindications for immediate implant placement.At the patient’s request,we perform immediate implant placement of the mandibular molars with CAP in clinical practice.AIM To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.METHODS The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery,the Affiliated Hospital of Qingdao University,from June 2015 to June 2017 were collected.The patients were divided into CAP(n=52)and no-CAP(n=45)groups.Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.RESULTS At 5 years after implantation,the peri-implant bone mineral density was 528.2±78.8 Hounsfield unit(HU)in the CAP group and 562.6±82.9 HU in the no-CAP group(P=0.126).Marginal bone resorption around implants did not differ significantly between the two groups,including buccal(P=0.268)or lingual(P=0.526)resorption in the vertical direction or buccal(P=0.428)or lingual(P=0.560)resorption in the horizontal direction.Changes in the peri-implant jump space did not differ significantly between the two groups,including the buccal(P=0.247)or lingual(P=0.604)space in the vertical direction or buccal(P=0.527)or lingual(P=0.707)space in the horizontal direction.The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density.In the CAP area,the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue(P<0.01).CONCLUSION The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results,without significant differences in the complications,survival rate,or bone tissue condition from the no-CAP mandibular molars.

Root Canal System Variation in Mandibular Second Molar: Middle-Mesial Canal

Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.

Transfer learning-based super-resolution in panoramic models for predicting mandibular third molar extraction difficulty: a multi-center study

Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.

Partial Molar Entropy and Partial Molar Heat Capacity of Electrons in Metals and Superconductors

There are at least two valid approaches to the thermodynamics of electrons in metals. One takes a microscopic view, based on models of electrons in metals and superconductor and uses statistical mechanics to calculate the total thermodynamic functions for the model-based system. Another uses partial molar quantities, which is a rigorous thermodynamic method to analyze systems with components that can cross phase boundaries and is particularly useful when applied to a system composed of interacting components. Partial molar quantities have not been widely used in the field of solid state physics. The present paper will explore the application of partial molar electronic entropy and partial molar electronic heat capacity to electrons in metals and superconductors. This provides information that is complementary information from other approaches to the thermodynamics of electrons in metals and superconductors and can provide additional insight into the properties of those materials. Furthermore, the application of partial molar quantities to electrons in metals and superconductors has direct relevance to long-standing problems in other fields, such as the thermodynamics of ions in solution and the thermodynamics of biological energy transformations. A unifying principle between reversible and irreversible thermodynamics is also discussed, including how this relates to the completeness of thermodynamic theory.

A Case Report of Kissing Molars Class III

Kissing molars (KMs), first reported by Van Hoof in 1973, refer to molars with occlusal surfaces that contact each other in a single follicular space while their roots extend in opposite directions. This is a case of a 20-year-old male who presented with complaints of right mandibular molar pain with cold water contact and occlusion. Panoramic and cone-beam computed tomography (CBCT) images revealed impaction of the right mandibular third and fourth molars, with the occlusal surfaces contacting each other while the roots extended in opposite directions. KMs are classified according to the impaction of the mandibular first and second molars (Class I), second and third molars (Class II), and third and fourth molars (Class III). Our patient was considered Class III. Given the patient’s preference for surgical treatment, successful teeth extraction and extirpation were performed under intravenous sedation. The patient’s postoperative course was unremarkable. We describe a case of KMs Class III with a cystic variant assessed by panoramic and CBCT images. We additionally review all KMs Class III reported in the literature.

Ketac Molar和Valux Plus龋齿修复的疗效观察

目的:观察并比较Ketac Molar易混型玻璃离子和Valux Plus光固化复合树脂以及银汞合金在龋齿修复中的疗效。方法:用随机抽样的方法,选择Ketac Molar易混型玻璃离子充填龋齿126颗,Valux Plus光固化复合树脂充填龋齿112颗,银汞合金充填龋齿98颗,连续观察2年,用统计学方法检验3组数据是否有统计学意义,评价其临床效果。结果:Ketac Molar易混型玻璃离子和Valux Plus光固化复合树脂及银汞合金充填2年复查,成功率分别为91.3%,91.1%,90.8%。三者2年充填成功率比较无统计学意义(P>0.05)。结论:Ketacmolar易混型玻璃离子与Valux Plus光固化复合树脂在龋齿充填中既能修复缺损牙体组织,而且美观,成功率高,是替代银汞合金的理想材料。

Intrusion of Overerupted Maxillary Molars with Miniscrew Implant Anchorage: A Radiographic Evaluation

The aim of this retrospective study was to quantitatively evaluate the treatment effects of in- trusion of overerupted maxillary molars using miniscrew implant anchorage and to investigate the apical root resorption after molar intrusion. The subjects included 30 patients whose average ages were 35.5±9.0 years. All patients had received intrusion treatments for overerupted maxillary molars with miniscrew anchorage. There were 38 maxillary first molars and 26 maxillary second molars to be in- truded. Two miniscrews were inserted in the buccal and palatal alveolar bone mesial to the overerupted molar. Force of 100-150 g was applied by the elastic chains between screw head and attachment on each side. Lateral cephalograms and panoramic radiographs taken before and after intrusion were used to evaluate dental changes and root resorption of molars. Only 6 of the 128 miniscrews failed. The first and second molars were significantly intruded by averages of 3.4 mm and 3.1 mm respectively （P〈0.001）. The average intrusion time was more than 6 months. The crown of the molars mesially tilted by averages of 3.1 degrees and 3.3 degrees （P〈0.001） for first and second molars. The amounts of root resorption were 0.2-0.4 mm on average. The intrusion treatment of overerupted molars with miniscrew anchorages could be used as an efficient and reliable method to recover lost restoration space for pros- thesis. Radiographically speaking, root resorption of molars was not clinically significant after applica- tion of intrusive forces of 200 to 300 g.

新型材料3M Ketac Molar超硬玻璃离子与银汞合金充填后牙窝洞的对比

背景:近年来,传统的银汞合金充填修复的缺点已日益显现。寻找其替代产品是目前研究的热点,而新型材料3M Ketac Molar超硬玻璃离子充填修复的报道尚不多见。目的:比较3M Ketac Molar超硬玻璃离子与银汞合金充填后牙窝洞的临床效果。设计、时间及地点:回顾性分析,对照观察,于2002-02/2006-04在南昌市第九医院口腔科完成。对象:选择南昌市第九医院口腔科门诊就诊的后牙龋病患者187例307颗牙,平均年龄45岁。方法:用3M Ketac Molar后牙超硬玻璃离子充填162颗后牙窝洞,银汞合金充填145颗后牙窝洞,连续观察1,2年,评价其临床效果,以充填材料完好,边缘密合,无继发龋、无磨损者为治疗成功。主要观察指标:两种材料修复后牙窝洞1,2年临床疗效。结果:3M Ketac Molar后牙超硬玻璃离子和银汞合金充填1年复查,成功率分别为96.30%,91.03%;2年复查,成功率分别为91.36%,90.34%。两组疗效差异无显著性意义(P>0.05)。结论:3M Ketac Molar后牙超硬玻璃离子既能修复缺损牙面,而且改善美观,防龋,是替代银汞合金的较好材料。

Three-dimensional computed topography analysis of a patient with an unusual anatomy of the maxillary second and third molars

We present a case of a patient with rare anatomy of a maxillary second molar with three mesiobuccal root canals and a maxillary third molar with four separate roots, identified using multi-slice computed topography （CT） and three-dimensional reconstruction techniques. The described case enriched/might enrich our knowledge about possible anatomical aberrations of maxillary molars. In addition, we demonstrate the role of multi-slice CT as an objective tool for confirmatory diagnosis and successful endodontic management.

Molar-Tooth构造成因争论分析

综述了Molar-Tooth的时空分布及其形态特征,Molar-Tooth为元古代时期全球性的一种构造现象.其成因,地质学家们已争论了一个多世纪,直到今天还未取得一致的认识.归纳前人的研究成果,初步认为Molar-Tooth的成因与藻类等生物活动有关.

Ketac Molar易混型玻璃离子充填后牙窝洞的临床效果

目的:观察比较Ketac Molar易混型玻璃离子和银汞合金分别充填后牙窝洞的临床效果。方法:用Ketac Molar易混型玻璃离子充填162个后牙窝洞,银汞合金充填145个后牙窝洞,连续观察1年、2年,评价其临床效果。结果:Ketac Molar易混型玻璃离子和银汞合金充填1年复查,成功率分别为96.30%,91.03%;2年复查,成功率分别为91.36%,90.34%。两组1年、2年治疗成功率比较无显著差异(P>0.05)。结论:Ketac Molar易混型玻璃离子既能修复缺损牙面,而且改善美观,防龋,是替代银汞合金的较好材料。

Studies on Lattice Parameter,Molar Volume and Excess Molar Volume of Pb-based a-phase Solid Solution in Pb-Sn-Cd Ternary System

The lattice parameters a and the molar volumes Km of Pb-based a-phase solid solutions in the Pb-Sn-Cd ternary system were determined by means of X-ray diffraction. The lattice parameters a vary linearly with the molar fractions, the molar volumes show a positive deviation from the ideal solution behaviour, and the contribution of the solute Cd to the excess molar volumes V is much larger than that of the solute Sn. According to Vegard' s law orsub-regular solution model, the relationship between the experimental data of a or Vm andthe compositions of alloy is obtained by the mathematic regressive method, the prediction precisions of the both formulae are within the limits of experiment error.

Root Canal Treatment of Mandibular First Molar with Radix Entomolaris

Aim: To confirm the effect of root canal treatment on radix entomolaris. Case: Radix entomolaris was an additional root that located on the distolingual of mandibular first molars. In this case, the radix entomolaris was detected clinically and radiographically with root canal configuration such as curves. An awareness and understanding of this unusual root and root canal morphology could contribute to the successful outcome of endodontic treatment. Conclusion: Root canal treatment on this case shows the lack of symptoms and normal radiographic presentation for two months follow-up.

Fusion of a Mandibular Third Molar and a Distomolar in a Trinidadian Child: Report of a Rare Case Diagnosed Using CBCT

Double teeth refer to two teeth that are totally or partially joined by dentin and maybe their pulps. These developmental anomalies may be the result of either gemination or fusion. This is a case of a 15-year-old Indo-Trinidadian male who presented with the fusion of a mandibular third molar with a distomolar as an incidental finding. The patient had his general dental care provided by a paediatric dentist and was referred to an oral and maxillofacial radiologist, orthodontist, and oral surgeon for consultation. A Cone-beam CT was taken to supplement the plain film periapical and orthopantomogram radiographs. It showed the three-dimensional orientation of the double molar and the extent of joining. This is the first case of fusion of a mandibular third molar to a distomolar being reported in the Caribbean.

沉积环境与臼齿构造(Molar-tooth)形态的关系——以大连新元古代臼齿构造为例

臼齿构造(Molartooth),简称MT,是一种仅发育于前寒武纪碳酸盐岩地层中的特殊沉积现象。在全世界的许多地区广泛发育。中国辽宁大连地区新元古代碳酸盐岩中发育了大量的臼齿构造。野外和室内的观察研究将MT形态划分为2大类(原地MT和异地MT),5亚类(条带状、杆状、蠕虫状、斑状和碎屑状),主要发育浅潮下带—潮间带环境。通过对MT形态及发育的微环境特征分析得出,大连地区MT形态与沉积微环境存在一定的对应关系。泻湖中以MT1-1和MT1-2类型为主,潮间带中部主要发育MT1-3和MT4类型,潮间带中部—潮间带上部常见MT2和MT3类型,浅潮下带风暴浪基面附近或潮间带下部高能环境多见MT5类型。由此推断,在水体安静并且陆源碎屑物质干扰小的环境中,容易产生平直或弯曲的宽、长条带状MT,而在动荡的水体中或是陆源碎屑物质含量高的环境中,往往形成短小的MT。因此,MT的形态类型一定程度受到沉积水动力条件和陆源碎屑物质混入的影响。此外,大量的陆源碎屑物质的混入或抑制MT形成或减小MT的发育规模。

Compensation trends of the angulation of first molars:retrospective study of 1403 malocclusion cases

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First,angulation of the upper first molar varied significantly with age and tipped most distally in cases aged,12 years and least distally in cases aged.16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

Impacted Lower Third Molar Fused with a Supernumerary Tooth—Diagnosis and Treatment Planning Using Cone-Beam Computed Tomography

This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radiography was complemented by the Donovan＇s radiographic technique; but because of the proximity of the dental element to the mandibular ramus, it was not possible to have a final fusion diagnosis. Hence, the Cone-Beam Computed Tomography--which provides precise three- dimensional information--was used to determinate the fusion diagnosis and also to help in the surgical planning. In this case report we observed that the periapical, occlusal and panoramic were not able to show details which could only be examined through the cone-beam computed tomo- graphy.