Posterior Mandibular Area Research Articles

심하게 결손된 하악 치조골에서 골유도재생술(GBR) 후 임플란트의 식립: 증례보고

In the mandibular posterior molar area, ridge deficiency is an unfortunate obstacle in the field of implant dentistry. Many techniques are available to rebuild the deficient ridge. Selection and necessity of these techniques are associated with significant morbidity and often require a second surgical site. With the advent of guided bone regeneration (GBR), one may now graft the deficient ridge with decreased morbidity and without a second surgical site. In this case, guided bone regeneration procedures were performed with a combination of allograft, xenograft, and alloplast, excepting autogerous bone at severe defected mandibular alveolar ridge and then placed to the implant successfully. We report that implant placement were good in two cases. (J Dent Rehabil Appl Sci

Accuracy of computerized vertical measurements on digital orthopantomographs: posterior mandibular region.

Objectives:Orthopantomographs are commonly used for diagnosis in clinical dentistry. Although the manufacturers claim a constant magnification effect, the reliability of measuring dimensions on the panoramic radiographs is not clear. The aim of this study was to evaluate the accuracy of measuring vertical dimensions in the posterior mandibular area on digital orthopantomographs.Materials and Methods:A retrospective survey of 20 orthopantomographs with unrestored implants (only with cover screw) in the mandibular posterior region (molars and premolars) was conducted. All radiographs were taken using the same machine by skilled technicians. Two examiners were asked to measure the vertical dimension of the implants seen on the radiographs viewed using two differently sized display screens. Inter-examiner and intra-examiner reliability tests were performed. Differences between the measured length and the actual length using each screen type were compared.Results:High coefficients of reliability were observed on intra- and inter-examiner correlation. The overall reliability of measuring the vertical dimensions of implants between both examiners for the large screen and the small screen were 97.4% (Cronbach's alpha 0.993) and 94.0% (Cronbach's alpha 0.984), respectively. There were no significant differences between the errors seen with either the large screen or the small screen, when each of them was compared to the original length (P = 0.146).Conclusion:This study shows that vertical dimensions in the posterior mandibular region (molar and premolars) can be reliably measured on an orthopantomograph using a calibrated machine and special software.

A Multicenter Clinical Study on the Survival and Success Rates of Two Commercial Implants of Korea according to Loading Period

Purpose: The purpose of this study was to evaluate the survival and success rates of Korean Osstem implants US II Plus, GS II following loading period. Materials and Methods: Dental records were obtained in total 201 patients who were treated with Korean Osstem implants US II Plus, GS II on both maxillary and mandibular anterior and posterior areas in six different clinics for 2 years from January 2007 to December 2008. Total 430 implants were evaluated clinically and radiographically using predefined success criteria prospectively and following results were obtained. Result: US II Plus, GS II implants showed high survival rates of more than 99% and high success rates more than 90% independent of loading period. As a result of cross analysis to evaluate clinical significance between implant loading period and success rate, the P-value of US II Plus was 0.10 (P>0.05), and the P-value of GS II was 0.17 (P>0.05), which showed no statistical significance. Bone quality, smoking, and edentulous state are factors that can affect the survival and success rates following differently loaded implants, but did not significantly affect in this study. Conclusion: These results suggest that selection of loading period of Korean Osstem implants US II Plus, GS II would be done carefully considering implant install area, the quality alveolar bone, the state of edentulous ridge and experience of operator, though they showed clinically good results on both maxillary and mandibular anterior and posterior areas.

나사유지형 임플란트 고정성 보철물의 적합도와 캔틸레버가 지지골조직의 응력분산에 미치는 영향

임플란트의 장기적인 성공을 위해 고정체의 형태, 외과적 술식, 골조직의 조건, 보철물 적합성, 주기적인 검사, 환자의 구강 위생 등에 많은 주의가 필요하다. 많은 연구에서 임플란트 지지 보철물의 적합도에 따른 임플란트의 예후에 관해 보고되었다. 보철물이 수동 적합되어야 임플란트의 상부구조및 하부구조에 해로운 응력을 야기하지 않는다고 보고되고 있으나 현재의 임플란트 보철물의 제작과정으로 진정한 수동 적합을 얻는 수 없다고 인정된다. 임상과정과 기공과정을 포함하여 임플란트 치료의 전 과정에서 오차가 발생하며, 이는 보철물을 변형을 야기하고 이는 임플란트 상부 보철물과 지대주 사이의 오차를 발생시킨다. 이러한 오차는 보철물 장착 후 보철물의 파절, 나사의 헐거움(screw loosening), 골소실, 골유착 실패와 같은 문제를 야기한다. 이런 오차에 의한 문제점은 cantilever의 존재, 과도한 교합력이 존재할 경우 더욱 증가된다고 보고되고 있다. 본 연구에서는 ITI 임플란트를 하악골의 견치후방의 무치악부에 3개를 식립하고 4-unit 캔틸레버 고정성 국소의치를 다양한 위치의 <TEX>$100{\mu}m$</TEX> gap을 생성한 후 제작하고 gap을 생성하지 않은 고정성 국소의치와 30 lb의 하중하에서 광탄성 응력분석을 시행하여 응력분포 양상과상대적인 응력의 크기를 비교분석하였다. A passively fitting prosthesis is an essential prerequisite to attain long-lasting success and maintenance of osseointegration. However, true "passive fit" can not be achieved with the present implant-supported prosthesis fabrication protocol. Many clinical situations are suitably treated with cantilevered implant-supported fixed restorations. The purpose of this study was to compare the stress distribution pattern and magnitude in supporting tissues around ITI implants with cantilevered, implant-supported, screw-retained fixed prosthesis according to the fitness of superstructures. Photoelastic model was made with PL-2 resin (Measurements, Raleigh, USA) and three ITI implants (<TEX>${\phi}4.1{\times}10mm$</TEX>) were placed in the mandibular posterior edentulous area distal to the canine. Anterior and posterior extended 4-unit cantilevered FPDs were made with different misfit in the superstructures. 4 types of prosthesis were made by placing a <TEX>$100{\mu}m$</TEX> gap between the abutment and the crown on the second premolar and/or the first molar. Photoelastic stress analysis were carried out to measure the fringe order around the implant supporting structure under simulated loading conditions (30 lb).

Displacement of dental implants into the focal osteoporotic bone marrow defect: a report of three cases

Focal osteoporotic bone marrow defect (FOBMD) is a radiolucent area corresponding to the presence of hematopoietic tissue rarely found in the jaws. FOBMD is most commonly located in the mandibular edentulous posterior area of a middle-aged female. From November 2011 to November 2012, we experienced three cases involving removal of implants that had accidentally fallen into the FOBMD area. All patients happened to be female, with a mean age of 54 years (range: 51-60 years). One case involved hypoesthesia of the lower lip and chin, while two cases healed without any complication. Displacement of an implant into the FOBMD area is an unusual event, which occurs rarely during placement of a dental fixture. The purpose of this study was to report on three cases of FOBMD and to provide a review of related literature.

Carcinoma de células escamosas intraóseo primario derivado de un tumor odontogénico queratoquístico: reporte de un caso y revisión de la literatura

Primary intraosseous squamous cell carcinoma (PIOSCC) derived from a keratocystic odontogenic tumour (KCOT) is a rare malignant bone tumour that exclusively involves the maxillary bones. It affects middle-age patients, mainly men, and is usually located in the posterior mandibular area. Clinically, it may exhibit classic characteristics of benign odontogenic tumors, though it may also be associated with pain and sensitive alterations.We present the case of an 86-year-old woman who was diagnosed with a PIOSCC derived from a KCOT.The imaging, clinical, and histological characteristics are described, and the importance of taking a biopsy from different parts of a cystic lesion that is characterized by extensive anatomical area involved are discussed.

소아에서 발생한 변연성 치아종의 증례보고

치아종(odontoma)은 치성기원의 과오종(hamartoma)으로서 법랑질, 상아질, 치수, 백악질 등의 조직으로 구성되어 있고, 조직학적으로 복합치아종과 복잡치아종으로 구분된다. 치아종은 영구치의 맹출을 방해하며 낭종 형성과 인접골 파괴를 유발할 수 있으므로 제거되어야 한다. 제거를 위해서는 적출술을 시행하고 재발은 거의 일어나지 않는다. 악골 외에 존재하는 치아종은 상대적으로 드문 질환으로 악골 내 치아종과 조직학적으로 유사한 특징을 보인다. 본 증례에서는 3세 여자 환아가 하악 우측 구치부 종창을 주소로 본원에 내원하였다. 정기적인 검사 결과 종창의 크기가 증가하였고, 방사선 검사를 통해 병소의 석회화를 확인하여 적출술을 시행하였다. 방사선 검사에서 골내 침식 소견은 관찰되지 않았고, 조직학적 검사를 통해 변연성 치아종으로 확진되었으며, 양호한 치료 결과를 보였기에 보고하는 바이다. The odontoma is a hamartoma of odontogenic origin and consists of enamel, dentin, cementum and pulp tissue. Two types of odonotma are histologically recognized: complex and compound. Odontoma may be the cause of noneruptoin or impaction of teeth, formation of cyst and resorption of adjacent bone. The recommended treatment for an odontoma is conservative surgical excision. No propensity for recurrence has been noted. Peripheral odontoma is relatively rare lesion and shows the histological characteristics of an intraosseous odontoma. This report described a 3-year-old Korean girl with a firm gingival mass in the posterior mandibular area, which had been gradually enlarging over 18months. Radiographic examination showed a radiopaque mass but no evidence of underlying intraosseous lesion. Excisional biopsy was performed for the mass removal and histopathological examination. The result of histopathological study was identified as hamartous supernumerary tooth germ. Based on the clinical presentation, radiographic and histopathologic findings, we concluded that the final diagnosis was peripheral odontoma. For three years after surgery, there is no clinical sign of recurrence.

Aneurysmal bone cyst of the mandible managed by conservative surgical therapy with preoperative embolization

A 9-year-old girl visited our hospital, complaining of a rapid-growing and rigid swelling on the left posterior mandibular area. Panoramic radiograph showed a moderately defined multilocular honeycomb appearance involving the left mandibular body. CT scan revealed an expansile, multilocular osteolytic lesion and multiple fluid levels within cystic spaces. Bone scan demonstrated increased radiotracer uptake and angiography showed a highly vascularized lesion. The lesion was suspected as aneurysmal bone cyst (ABC) and preoperative embolization was performed, which minimize the extent of operation and the surgical complication. The lesion was treated by surgical curettage and lateral decortication with repositioning. No additional treatment such as a surgical reconstruction or bone graft was needed. Early diagnosis of ABC is very important and appropriate treatment should be performed considering several factors such as age, surgical complication, and possibility of recurrence.

Implant Displacement into the Mandible: An Unusual Complication During Implant Surgery

In contrast with problems regarding initial stability of dental implants in the posterior maxilla, heat generation during bone drilling is one of the complications that can occur in the mandible which is usually composed of dense bone. This report presents an unusual case of implant displacement into the mandibular posterior area of a middle-aged woman. This problem was presumably caused by poor bone density, loss of cortical bone engagement, and differences in bone quality between the alveolar bone and the basal bone.

Maxillary anterior and mandibular posterior residual ridge resorption in patients wearing a mandibular implant-retained overdenture

The mandibular implant-retained overdenture could improve masticatory function compared to the conventional complete denture. However, increased forces exerted by the overdenture could increase residual ridge resorption of the maxillary anterior and mandibular posterior areas. The aim of this study was to compare the effect of the mandibular implant-retained overdenture using two or four dental implants, or the conventional complete denture on resorption of the residual ridge of the maxillary anterior and mandibular posterior areas over a period of 10 years. In total, 120 patients, 30 patients treated with an overdenture on two implants (two-implant group), 30 patients with an overdenture on four implants (four-implant group) and 60 patients treated with a conventional full denture (conventional group), participated in this study. On panoramic radiographs, made before and 10 years after treatment, proportional area measurements were applied to determine changes in bone height. After 10 years, a statistically significant amount of bone resorption had occurred in the anterior maxilla in the two-implant group and in the four-implant group. A significant amount of bone resorption had occurred in the posterior mandible in all three groups. There were no statistically significant differences between the groups in both areas. Patients presented large individual differences. It is concluded that patients rehabilitated with implant-retained mandibular overdentures are not subjected to more residual ridge resorption in the anterior maxilla when compared to patients wearing a conventional full denture. Regarding the mandibular posterior residual ridge, resorption was irrespective of wearing an implant-retained mandibular overdenture or a conventional mandibular denture.

Application of a narrow-diameter implant in a limited space

This report presents a case of inadequate space distribution after orthodontic treatment, when a narrow-diameter implant was placed in a limited mandibular anterior space (ridge and prosthetic). A 26-year-old female patient presented with a purulent discharge from the mandibular right posterior area. Radiographic and clinical evaluations revealed a four-unit bridge spanning teeth 42 to 43 and acute apical periodontitis with root resorption around tooth 42. After careful evaluation, tooth 42 was extracted, and orthodontic treatment was performed to align the posterior teeth and create a dimensionally appropriate space between teeth 41 and 43. A 3i MicroMiniplant with dimensions of 3.25 mm (diameter) × 11.5 mm was implanted in the edentulous area of tooth 42 because of the small size of tooth 42. Autogenous bone particles were placed on the buccal crestal defect, and a healing abutment was attached. After an 8-month healing phase, a final impression was made and an all-ceramic crown was delivered. This case demonstrates that osseous sites with significant dimensional space limitations can be successfully utilized to receive and integrate a narrow-diameter implant that will satisfy esthetic, phonetic and functional requirements.

Evaluation of Mandibular Posterior Single Implants With Two Different Surfaces: A 5‐Year Comparative Study

Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.

Surgical management of ameloblastoma in children

The purpose of this study was to report experience in the treatment of ameloblastoma in Taiwanese children and to discuss the treatment regimen. Fifteen patients, all younger than 18 years of age, with a diagnosis of ameloblastoma in our department between January 1991 and December 2004 were selected for study. Data included sex, age at surgery, tumor type, size and site of lesion, primary surgical methods, use of adjuvant therapy, complications, recurrences, and course of follow-up. Ages ranged from 9 to 17 (average was 13.7 years). Nine were male, 6 were female; the sex ratio was 1.5:1. Fourteen lesions were in the mandible (1 in the symphysis, 13 in the mandibular posterior area) and only 1 was in the maxilla. The size of the lesions ranged from 4 x 2.5 cm to 8 x 8 cm. Clinical typing included 8 unicystic type, 3 multicystic type, and 4 solid types. Of the histologic types, 5 were plexiform, 3 were mixed type, and 3 were acanthomatous type. Complications included numbness of the lower lip and contour defect of the face. Three cases (20%) were recurrent, and 1 patient had 2 recurrences. Good results can be achieved in the treatment of ameloblastoma in children using conservative surgery. In the event of recurrence, a second surgery can be successful. Patient compliance and careful follow-up are important.

A very rare form of leiomyoma: Mandibular angioleiomyoma

Mandibular angioleiomyomas are extremely exceptional, and they may stem from the smooth muscle of vessel walls, aberrant adnexial smooth muscle, arteriovenous anastomoses, ectopic thyroglossal ducts and hamartomas. In this report, a case of angioleiomyoma in the posterior mandibular area was presented, and aetiological, clinical, radiographical, histological characteristics and treatment modalities of the lesion were discussed.

A 7-year Follow-up of 93 Immediately Loaded Titanium Dental Implants

Recently, several experimental and clinical investigations found that immediately loaded implants obtained satisfactory levels of osseointegration with high success percentages. Only a few long-term studies of immediately loaded implants have been reported in the literature. The aim of this study was a 7-year clinical and radiographic follow-up of 93 immediately loaded dental implants in human patients. Eleven patients were consecutively enrolled in this study. A total of 7 full and 9 partial edentulous arches were rehabilitated. Patients presented a completely edentulous mandible (n=6), a completely edentulous maxilla (n=1), mandibular posterior edentulous areas (n=5), or a posterior maxillary edentulous area (n=1). Patients were rehabilitated with a bar and an overdenture (n=4), a provisional prosthesis of 3 to 12 elements (n=11), or a metal-ceramic bridge of 10 elements (n=1). A total of 93 implants were inserted and loaded within a 24-hour time frame. Six implants failed in the first year after loading. No more failures were observed in the following 6 years, and all the other implants were well integrated from a clinical and radiographic point of view. The cumulative success rate at 7 years was 93.5%, and the prostheses survival rate was 98.5%. The mean marginal bone loss was 0.6 mm after the first year and 1.1 mm at the 7-year evaluation. Primary stability is one of the most important parameters in immediately loaded implants because it avoids micromotion at the bone-implant interface. Four of the 6 failures in our patients occurred in partially edentulous patients; an excessive load applied to these small bridges could be the reason for the failure. Also, the bone quality is important, for 3 of our failed implants had been inserted in D3 bone. Our clinical and radiographic results have shown that these immediately loaded implants have remained osseointegrated for a long period. Our results point to the possibility of using the immediate loading technique in selected and well-informed cases.

The comparison between 2 wide implants and 3 regular implants in mandibular posterior area

The comparison between 2 wide implants and 3 regular implants in mandibular posterior area

Ameloblastic fibrodentinoma: Report of two cases

Two cases of ameloblastic fibrodentinoma localized in the posterior mandibular area are presented. The clinical and histological findings are discussed.

Lingual mandibular sequestration and ulceration

This study analyzed 11 patients who had small sequestra associated with ulceration of the lingual mucosa in the posterior mandibular molar area at the level of the mylohyoid ridge. The patients were adults (mean age, 45.3 years) with complaints of sensitive, occasionally painful lesions that appeared for periods that ranged from 1 week to several months. No abnormalities were evident on periapical radiographs; however, in three cases in which occlusal radiographs were available, small irregular radiopacities contiguous with the cortex were noted. Spontaneous exfoliation or surgical removal of the sequestrum resulted in resolution of the lesion. The possible etiologic factors associated with this apparent clinical-pathologic entity are discussed.

Skeletal Alterations as a Basis for Facial Rejuvenation

A slight decrease in overall facial bone bulk coupled with the increased soft-tissue expansion associated with aging produce effects that should be reversed in both the bone and soft tissue where possible. The changes are best done at the ledge areas: the supraorbital-temporal ridge areas, malar-midface, and chin mandible. However, the overall bone bulk may be increased in addition in the temporal fossae, in the infraorbital rim, at the lateral canthus, in the paranasal area, and at the alveolar ridges and dental areas. A combination of autogenous and synthetic materials is currently best, with synthetic materials most useful in the malar-midface, posterior mandibular, infraorbital, and paranasal areas. In the supraorbital ridge-temporal areas, it is a near equal choice between autogenous and synthetic materials. In the chin, the preferred method is by osteotomy using autogenous augmentation. The concept of increasing bone mass and decreasing expanded soft-tissue mass has application within the judgment of the surgeon coupled with the patient's desires. Subtle increases of bone mass to compensate for soft-tissue thinning as well as bone shrinkage, at the same time taking up lax soft tissue, can be done in conjunction with one another, effectively producing a three-layer face lift. The subperiosteal face lift is in reality an extended brow lift and can be used to enhance the brow-forehead area and the temporal, zygomatic, and paranasal areas. At the same time, the perioral, jowl, and submandibular regions must be treated by a combination of standard face lifting procedures and augmentation of the bone structures of the face.

Periodontal Disease Morbidity Quantification. I. Optimal Selection of Teeth for Periodontal Bone Loss Surveys

The assessment of alveolar bone loss with bite-wing radiographs is attractive because bite wings are relatively convenient, inexpensive, and available. The choice of teeth used influences the validity of global bone loss assessments based on partial mouth measurements. The objective of this study was to validate periodontal bone loss indices based on a few teeth. The mandibular posterior teeth were considered as a basis for abbreviated indices. The optimum number of teeth included was evaluated, and the utility of abbreviated indices was determined experimentally. The teeth from 75 skulls were measured from the cemento-enamel junction (CEJ) to the alveolar bone at six locations per tooth. The subsets of teeth which best represent the average whole mouth bone loss were found with all-possible-subsets regression analysis. Bone loss data from 179 prehistoric skulls were used to test the validity of selected teeth indices. Bone loss measurements from the mandibular posterior areas were representative of full-mouth bone loss measurements. Mandibular second premolars plus any other mandibular posterior teeth were the optimal combination of tooth for an abbreviated index. This subset is suitable for use with bite-wing radiographs.