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Objective@#To investigate the soft and hard tissue morphology in the infrazygomatic crest zone by observing the cone-beam computed tomography (CBCT) scans in patients with mini-implants.@*Methods@#CBCT scans of 43 patients performed from January 2014 to December 2016 in the Department of Stomatology, Beijing Friendship Hospital, Capital Medical University, with 84 existing mini-implants in the infrazygomatic crest region were collected. The bone thickness and cortical bone thickness were measured in the palatal and buccal side of the mini-implant. The maxillary sinus membrane thickness, sinus septa, reverse fold, and the sinus opening angle were also determined and analyzed in the maxillary posterior region.@*Results@#The bone thicknesses in the buccal and palatal side of the existing mini-implant were 2.5 (1.5, 3.2) and 5.2 (4.0, 6.4) mm, respectively. However, the corresponding cortical bone thicknesses were only 2.1 (1.3, 2.8) and 1.5 (1.0, 1.9) mm, respectively. The prevalences of the septa and the reverse fold were 33% (28/84) and 45% (38/84), respectively. The sinus opening angle was the largest in the mid-coronal plane of the maxillary first molar (71.6°±15.6°). In the coronal plane located at 10 mm mesially, the angle was the smallest (46.1°±18.0°), and in this area, 20% (16/82) of the angle was less than 30°.@*Conclusions@#The outer cortical plate of the infrazygomatic crest along with the cortical plate of sinus floor could be related to the initial stability of mini-implant anchorage. The anatomic variation such as the reverse fold indicated thorough consideration of insertion depth and angle to avoid unexpected sinus injury.
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Objective@#To observe the long-term clinical treatment outcome and the influencing factors of the outcome for the teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration. To summarize the clinical guidelines of modified crown lengthening surgery in selection of indications and for mulation of treatment planning.@*Methods@#Fifty-seven patients with a total of 67 teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration for at least a 6 months' follow-up period between July 2004 and July 2013 were recruited in this retrospective study by phone call interviews. The patients' clinical outcomes were evaluated by the combination of clinical examination, radiograph and questionnaire regarding patient-reported outcome of the last follow up (≥9 months post modified crown lengthening surgery and ≥6 months after definite crown restorations). All of the treated teeth were classified into two groups, group A (teeth with good clinical treatment outcome) and group B (teeth with poor clinical treatment outcome), based on the defined criteria including patients' satisfaction with the function and esthetics of the teeth and absence of periodontal, endodontic and prosthodontic complications. The potential influencing factors of clinical treatment outcome were also determined by Logistic regression analysis.@*Results@#Vertical root fracture in 1 tooth was found on its periapical film and the tooth was deemed hopeless. Thus, the survival rate is 99% (66/67) for the multidisciplinary treatment approach. Seventy-two percent (48/67) of the teeth achieved good clinical treatment outcome and 28% (19/67) of the teeth developed one or several complications. In group B (teeth with poor clinical treatment), 16 out of teeth exhibited periodontal complications with bleeding on probing (BOP) positive mostly found. Logistic regression analysis demonstrated that plaque control (OR=21.392, P=0.014), edge form (OR=7.610, P=0.011), and smoking experience (OR=7.315, P=0.018) were the risk factors influencing the clinical treatment outcome of modified crown lengthening surgery combined with root canal treatment and post-core restoration.@*Conclusions@#Modified crown lengthening surgery combined with root canal treatment and post-core restoration has a good and stable clinical effect in the observational time of 6-114 months. Plaque control, smoking status and edge form of the tooth appeared to be the influencing factors of this multidisciplinary treatment approach.
ABSTRACT
SUMMARY In this article , different methods to deal with teeth fractures were discussed by presenting a case of traumatic crown-root fracture in the anterior esthetic zone .The traumatic crown-root fracture is a common problem in clinic .When a fracture line locates in close proximity to or below the alveolar bone crest , the fracture most likely involve the junctional epithelium and the connective tissue attachment .This type of fracture becomes a challenge for restorative dentists because it involves biologic , functional , and es-thetic considerations , especially when the fracture occurs in an esthetic area .In this case , a young patient presented with two fractured upper anterior teeth to the Department of Periodontics , Peking University School and Hospital of Stomatology .After the comprehensive clinical evaluation , the right central incisor was decided to extract for implant therapy and the right lateral incisor was decided to retain by one modified crown lengthening surgery .The most common technique applied to save a retained root is a clinical crown lengthening procedure .However , the aggressive alveolar bone resection of both target and adjacent teeth to reestablish the bone width and periodontal health may compromise functional and esthetic outcomes .To re-duce loss of excessive osseous tissue during osteotomy procedure , the modified crown lengthening of the right lateral incisor was performed , including minor bone resection and root reshaping .Regarding the right central incisor , the retained root was all located below the alveolar bone crest .The extraction and implant procedure , combined with guided bone graft were performed to avoid the damage to neighbor teeth during traditional restorative therapy and to reshape a preferable buccal contour .At the last visit , the patient was recalled with healthy periodontium , normal tooth function and favorable esthetic results .