牙源性角化囊肿手术对咀嚼效能的影响

目的：评价下颌骨牙源性角化囊肿手术及可摘部分义齿修复对患者咀嚼效能的影响。方法：通过临床检查和复习X线片明确术前囊肿累及的牙数和术后的缺失牙数,采用吸光度法测定咀嚼效率。对结果进行比较和统计学分析。结果：手术后的平均失牙数下颌骨部分切除术组明显多于囊肿剜除术组和袋形术组;可摘部分义齿修复前及修复后的吸光度值,颌骨切除术组均低于囊肿剜除术和袋形术组（P〈0．01）;囊肿剜除术和颌骨切除术组义齿修复后吸光度值明显提高（P〈0．01）。结论：下颌骨牙源性角化囊肿手术后患者咀嚼效能变化与手术方法或牙缺失数有关。术后可摘部分义齿修复可明显改善患者的咀嚼功能。     

Implant placement under existing removable dental prostheses and its effect on masticatory performance

Objective

The aim of this within-subject study was to evaluate the outcome with implant-tooth-supported removable partial dental prostheses (RPDP group) and implant-supported removable complete dental prostheses (edentulous group) in terms of masticatory performance and self-assessment.

Materials and methods

Thirty patients participated in this prospective clinical study (RPDP group: n = 12; edentulous group: n = 18). The prostheses were supported in strategically advantageous regions by placing implants with ball attachments and corresponding matrices in the existing dentures. The masticatory performance was evaluated with the Swallowing Threshold Test Index (STTI), the number of chewing strokes, and the time needed until swallowing at pre-treatment and 6 weeks after integration of ball attachments. Additionally, patients scored chewing satisfaction before and after implantation on a visual analogue scale.

Results

The STTI increased significantly (p ≤ 0.05) after implant therapy in the edentulous group but not in the RPDP group. Furthermore, the STTI was significantly higher (p ≤ 0.05) in the RPDP group than in the edentulous group at pre-treatment, however, not after therapy (P > 0.05). All patients were very satisfied after therapy concerning ability of speaking, chewing, and stability of their prosthesis.

Conclusions

Patients of the edentulous group benefit more from strategically placed implants under the existing dentures than patients from the RPDP group. However, according to the subjective assessment, the chewing satisfaction generally increased for both groups after implant therapy.

Clinical relevance

Patients with a strongly reduced dentition and edentulous patients benefit from strategically placed implants under the existing removable dentures.

     

Influence of working side contacts on masticatory function for mandibular distal extension removable partial dentures

The aim of this study was to clarify the influence of working side contacts for masticatory function for a distal extension removable partial denture. Five subjects who had edentulous arches from second premolar to second molar opposing natural teeth participated. Working side contacts were altered by using three types of artificial teeth attached to the denture base. A-form teeth made contact with opposite teeth while acting as the working side in a lateral excursion. The cusp angles of B- and C-form teeth were decreased by 10 degrees and 20 degrees, respectively compared with A-form teeth. B-and C-form teeth discluded with opposite teeth on the working side. Subjects were asked to perform two kinds of masticatory performance test. Obtained data were evaluated by the repeated-measures anova and the Tukey test for multiple comparisons. Results revealed that there was a significant difference (P=0.001) in the three types of teeth in the mixing ability test and the value of A-form teeth was statistically less value than those of the other teeth. However, there was no significant difference in the comminuting ability test. These results suggested that working side contacts between artificial teeth and opposite natural teeth influenced mixing ability, but not comminuting ability.     

Endoscopically assisted enucleation and curettage of large mandibular odontogenic keratocyst

This article reports a case of a mandibular multilocular keratocyst treated with endoscopically assisted enucleation and curettage. An ectopic third molar displaced in the coronoid process area was also removed.Odontogenic keratocysts (OKCs) are known for their propensity to recur. The incomplete removal of the cyst is one of the mechanisms for which it is thought that the keratocyst recurs. The endoscopic assistance allowed us to explore accurately the operative field and the areas of difficult access, improving the complete removal of the cystic lesion. Moreover, it allowed us to monitor closely the separation of the cyst lining from the inferior alveolar nerve and limit the extension of the surgical approach. At 3-year follow-up no evidence of recurrence was evidenced by radiological and clinical controls.     

Provisional removable partial and complete prostheses

The incorporation of the use of provisional removable complete and partial prostheses is an extremely valuable diagnostic and therapeutic modality in the comprehensive rehabilitation of the partially and fully edentulous patient. There is no question that the use of this restoration addresses many of the chief complaints of patients in a timely fashion and, in so doing, builds a high degree of confidence in the dentist by the patient. The evaluation of the provisional restorations and their subsequent refinement results in a higher quality, more predictable definitive restoration. Experience has demonstrated that postinsertion problems are reduced with the definitive prosthesis following successful therapy with the provisional restoration. The provisional prosthesis is also valuable as a "spare" denture after insertion of the definitive prosthesis. The role of the provisional removable prosthesis is readily understood and accepted by most patients, and the appropriate use of these restorations in prosthetic dentistry is an indication of a high-quality, highly individualized, and service-oriented dental practice.     

单侧游离端义齿咀嚼效能的测定和分析

采用吸光度法测定３０例肯氏Ⅱ类牙列缺损患者戴用单侧游离端可摘义齿前及用后１周，１月，３月的咀嚼效能。结果表明；１肯氏Ⅱ类牙列缺失患者咀嚼效能明显低于正常对照组，失牙越多，单侧丧失咀嚼效能越明显，失牙较少时，机体可通过代偿维持吞咽反射前的儿能。２．戴用义齿后，患者的咀嚼效能随戴用时间的增长而逐步提高。     

Influence of interocclusal distance of mandibular unilateral distal extension removable partial denture on masticatory function]

The purpose of this study was to elucidate the influence on masticatory function when the mandibular unilateral distal extension removable partial denture changed the interocclusal distance. The experiments, crushability, the sense of mastication, and the masticatory strokes until swallowing, were conducted, on four subjects, using the denture with the apparatus that enabled to change the interocclusal distance. The results were as follows: The particle size distribution showed that the ratio of small particle (diameter 2.5-4.5 mm) decreased, while that of large particle (more than 5.0 mm) increased, on three of four subjects, and the value of crushability diminished. A reduction of the value of crushability when the interocclusal distance was extended more than 800 microns was found. As for the other subject, no change was recognized on the particle size distribution under experimental condition, and the value of crushability showed no significant change.     

Influence of length of food platform on masticatory performance in patients missing unilateral mandibular molars with distal extension removable partial dentures

Reduction of the size of food platform of a distal extension removable partial denture has been recommended to decrease functional load on the abutment teeth and residual ridges. The purpose of this study was to investigate the influence of shortening food platform on masticatory performance. Eight subjects unilaterally missing mandibular molars participated in the study. A unilateral design was used for the denture framework. The length of the food platform was changed as follows. Initially, (A) was adjusted so that the distal end of the platform was in accordance with the distal end of maxillary second molar. Next, the platform was shortened successively to 15 mm (B) and 10 mm (C). Subjects were asked to masticate 2-colored wax cubes to evaluate masticatory performance. Mixing Ability Index was calculated from the color mixture and the form of masticated cubes. Repeated measures one-way ANOVA indicated significant difference of Mixing Ability Index among platforms (P < 0.0001). The Dunnett's test indicated no significant difference between A (1.27 +/- 0.29) and B (1.36 +/- 0.29), and a significant difference between A and C (0.89 +/- 0.30), (P < 0.001). Masticatory performance decreased significantly when the length of food platform was shortened to 10 mm.     

减压术治疗下颌骨大型牙源性角化囊肿的临床研究

目的：评价减压术治疗下颌骨大型牙源性角化囊肿的疗效。方法：回顾1999年10月至2004年10月61例经减压术治疗的下颌骨大型角化囊肿病例．随访6个月～5a，进行临床、影像学及病理学检查，在全景片上测量减压术后病灶的长径变化，评价临床疗效．随访观察复发情况：采用SAS6．12统计软件包进行X^2检验，计算Fisher确切慨率。结果：临床及影像学检查显示，囊肿周同骨质再生改建，囊腔逐渐缩小．被推移的下牙槽神经血管束恢复至正常位置，倾斜移位的牙长轴逐渐纠正减乐术后引流期维持6～23个月，中位时间14个月。减压术治疗颌骨大型角化囊肿的有效率为91．8％，单房型角化囊肿的疗效优于多房型，不同年龄组间的有效率在统计学上无显著差异。本组资料随访期间未发现复发。结论：减乐术是治疗下颌骨大型牙源性角化囊肿的有效方法。     

Clinicopathological study of odontogenic keratocyst

Fifty-five cases of odontogenic keratocyst in the mandible were classified into two subtypes according to the histopathologic characteristics of the epithelium (Group-1; the epithelium was parakeratotic with cuboidal or columnar, accentuated and palisadelike arranged basal cells, Group-2; the epithelium was orthokeratotic with a distinct stratum granulosum.) and were examined for the following four factors; 1) age distribution, 2) size of bone destruction, 3) degree of lateral bone expansion, and 4) features of the cyst contents. Most cases of Group-1 indicated radiographically lateral bone expansion and large cystic bone destruction and had fluid cyst content. On the contrary, the majority of Group-2 cases indicated no lateral bone expansion, were relatively small lesions, and their cystic cavities were filled with caseous materials.     

Solid variant of odontogenic keratocyst

A case of an unusual lesion from the maxilla is presented. Macroscopically, the lesion was solid and histologically consisted of 'multiple separate keratocysts' of varying size that infiltrated into the surrounding bone and soft tissues. Panoramic image and CT scans showed a multilocular honeycomb ill-defined radiolucency with infiltration into the maxillary sinus and floor of orbit. This lesion should be differentiated from similar odontogenic lesions, such as keratoameloblastoma and papilliferous keratoameloblastoma. As there was no evidence of follicles, islands of ameloblastoma, or papilliferous structures in the entire specimen, the lesion could not be diagnosed as either a keratoameloblastoma or a papilliferous keratoameloblastoma. The invasive and destructive growth behavior, the histopathological features, and the histochemical pattern of the collagen stroma imply that this solid lesion is a neoplasia. It is suggested that the proper term for this lesion is solid variant of odontogenic keratocyst.