Interrelationship between implant and orthognathic surgery for the rehabilitation of edentulous cleft palate patients: a case report

A 43-year-old woman with a unilateral cleft lip and palate, presenting a totally edentulous maxilla and mandible with marked maxillomandibular discrepancy, attended the Prosthodontics section of the Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo for treatment. She could not close her mouth and was dissatisfied with her complete dentures. Treatment planning comprised placement of six implants in the maxilla, four in the mandible followed by prostheses installation and orthognathic surgery. The mandibular full arch prosthesis guided the occlusion for orthognathic positioning of the maxilla. The maxillary complete prosthesis was designed to assist the orthognathic surgery with a provisional prosthesis (no metal framework), allowing reverse treatment planning. Maxillary and mandibular realignment was performed. Three months later, a relapse in the position of the maxilla was observed, which was offset with a new maxillary prosthesis. This isa complex interdisciplinary treatment and two-year follow-up is presented and discussed. It should be considered that this type of treatment could also be applied in non-cleft patients.     

钛基台支持的CAD/CAM全瓷单冠不同载荷位置的三维有限元应力分析

目的分析钛基台支持的CAD/CAM全瓷单冠在载荷位置不同时全冠的应力情况,为种植上部结构的临床设计提供理论参考。方法建立钛基台以及粘接固位的下颌第二前磨牙牙冠的三维有限元模型,在基台上方偏颊侧(a)、基台正上方(b)、基台上方偏舌侧(c)的牙冠■面3个不同部位分别施加300N的轴向静载荷,计算分析全冠的应力情况。结果对于玻璃陶瓷全冠,当载荷作用于位置a时,最大拉应力在舌侧颈缘处,约为13MPa;最大压应力位于颊侧颈缘处,约为-45MPa。载荷作用于位置b时,最大拉应力在与基台顶部中心区域接触处的牙冠组织面,约为20MPa。载荷作用于位置c时,最大拉应力在牙冠颊侧颈缘处约为15MPa;舌侧颈缘处最大压应力值为-40MPa。氧化锆全冠在三种载荷类型时的应力场分布与玻璃陶瓷全冠类似,应力值大小不同。结论钛基台支持的CAD/CAM全瓷单冠,当载荷作用于位置a时,牙冠颊侧颈缘应增加强度以防止折裂,牙冠舌侧颈缘处应防止脱粘接;载荷作用于位置b时,基台上方牙冠■面需要增加强度;载荷作用于位置c时,牙冠颊侧颈缘处易发生脱粘接,舌侧颈缘处容易折裂。     

Comparison of immediate complete denture, tooth and implant-supported overdenture on vertical dimension and muscle activity

PURPOSE

To compare the changes in the occlusal vertical dimension, activity of masseter muscles and biting force after insertion of immediate denture constructed with conventional, tooth-supported and Implant-supported immediate mandibular complete denture.

MATERIALS AND METHODS

Patients were selected and treatment was carried out with all the three different concepts i.e, immediate denture constructed with conventional (Group A), tooth-supported (Group B) and Implant-supported (Group C) immediate mandibular complete dentures. Parameters of evaluation and comparison were occlusal vertical dimension measured by radiograph (at three different time intervals), Masseter muscle electromyographic (EMG) measurement by EMG analysis (at three different positions of jaws) and bite force measured by force transducer (at two different time intervals). The obtained data were statistically analyzed by using ANOVA-F test at 5% level of significance. If the F test was significant, Least Significant Difference test was performed to test further significant differences between variables.

RESULTS

Comparison between mean differences in occlusal vertical dimension for tested groups showed that it was only statistically significant at 1 year after immediate dentures insertion. Comparison between mean differences in wavelet packet coefficients of the electromyographic signals of masseter muscles for tested groups was not significant at rest position, but significant at initial contact position and maximum voluntary clench position. Comparison between mean differences in maximum biting force for tested groups was not statistically significant at 5% level of significance.

CONCLUSION

Immediate complete overdentures whether tooth or implant supported prosthesis is recommended than totally mucosal supported prosthesis.     

IN VITRO EVALUATION OF THE PRECISION OF WORKING CASTS FOR IMPLANT-SUPPORTED RESTORATION WITH MULTIPLE ABUTMENTS

Objective:

The purpose of this study was to compare the accuracy of two working cast fabrication techniques using strain- gauge analysis.

Methods:

Two working cast fabrication methods were evaluated. Based on a master model, 20 working casts were fabricated by means of an indirect impression technique using polyether after splinting the square transfer copings with acrylic resin. Specimens were assigned to 2 groups (n=10): Group A (GA): type IV dental stone was poured around the abutment analogs in the conventional way; Group B (GB), the dental stone was poured in two stages. Spacers were used over the abutment analogs (rubber tubes) and type IV dental stone was poured around the abutment analogs in the conventional way. After the stone had hardened completely, the spacers were removed and more stone was inserted in the spaces created. Six strain-gauges (Excel Ltd.), positioned in a cast bar, which was dimensionally accurate (perfect fit) to the master model, recorded the microstrains generated by each specimen. Data were analyzed statistically by the variance analysis (ANOVA) and Tukey''s test (α= 5%).

Results:

The microstrain values (με) were (mean±SD): GA: 263.7±109.07με, and GB: 193.73±78.83με.

Conclusion:

There was no statistical difference between the two methods studied.     

A non-invasive method for the assessment of gingival thickness in the aesthetic zone and the concept of the gingival geometric ratio in an Asian population

The aim of this study was to investigate the gingival thickness and biologic width in the aesthetic zone (maxillary central and lateral incisors) in an Asian population using cone beam computed tomography (CBCT) as a non-invasive measurement method, prior to immediate implant placement. The gingival geometric ratio is introduced as a new parameter for assessing soft tissue stability and hence predicting the aesthetic outcome. The gingival thickness, biologic width category (normal, high, and low crest), and gingival geometric ratio (shape and configuration of the gingival tissues) were assessed for 171 central and 175 lateral incisors on high-resolution CBCT images. Thick gingivae were found in 93.6% of the central incisors and 64% of the lateral incisors (P < 0.001). The difference in thickness between the central and lateral incisors was statistically significant (P < 0.001). Regarding the biologic width of the facial gingival tissue, the majority of central (64.8%) and lateral (64.3%) incisors were categorized as low crest (>3 mm). The study found that most of the gingivae of the maxillary central incisors were thick, while thin gingivae were more prevalent in the lateral incisors. Therefore, an individual patient may have different gingival thickness types, and ‘one individual, one gingival biotype’ may not be true. Furthermore, the majority of the facial gingival tissues of the maxillary incisors were found to be low crest.     

球帽和Locator附着体种植覆盖义齿的临床疗效评价

目的:评价球帽附着体和Locator附着体应用于种植覆盖义齿的临床效果.方法:纳入无牙颌患者67例,共植入150颗Straumann或Bego种植体,完成球帽式或Locator式种植覆盖义齿修复.定期随访复查,包括修复后生物并发症和机械并发症情况和患者满意度调查.采用SPSS 17.0软件统计分析.结果:完成随访58例,球帽组35例,Locator组26例,球帽改Locator组7例.生物并发症比较显示,球帽组的牙龈增生发生率明显高于Locator组(P＜0.05);球帽组和Locator组的机械并发症发生率无显著差异(P＞0.05),但Locator组各类机械并发症的发生次数少于球帽组,球帽组平均修理频次为1.9次,Locator组为0.9次;Locator组患者对咀嚼和固位的满意度高于球帽组,不同性别的患者满意度无差异,满意度与患者的年龄和随访时间无相关性.结论:Locator式种植覆盖义齿相比球帽式种植覆盖义齿,临床效果具有一定优势.     

Inflammatory papillary hyperplasia of the palate: treatment with carbon dioxide laser, followed by restoration with an implant-supported prosthesis

Inflammatory papillary hyperplasia of the palate is a persistant non-neoplastic lesion that is normally caused by poorly fitting dentures and Candida infection. We describe a case that was managed primarily with topical miconazole, and complete removal of the old acrylic denture. A multidisciplinary approach between surgeon and prosthodontist was used that combined carbon dioxide laser followed by substitution of the old removable denture for a new implant-supported screw retained prosthesis. This avoided direct support of the prosthesis by the palatal mucosa and made oral hygiene easier. The treatment has resulted in complete remission and there has been no recurrence occurred during 3 years of follow-up.     

冲击载荷下骨外段种植基桩不同高度对下颌覆盖总义齿应力分布的影响

目的 分析骨外段种植基桩高度不同对下颌种植覆盖总义齿应力分布的影响。方法 应用ＣＴ扫描法建立下颌种植覆盖总义齿三维有限元模型,分析冲击载荷下骨外段种植基桩高度不同对下颌种植覆盖总义齿应力分布的影响。结果 随种植基桩高度的降低,种植体内部及种植体软硬组织界面应力分布更为均匀。结论 在保证义齿固位稳定的前提下,在一定范围内降低种植体骨外段基桩高度有利于保护种植体及其周围软硬组织健康。     

两种上部结构设计在前牙区种植修复的临床效果研究

目的:比较两种不同的上部结构设计在上颌前牙区单颗牙种植修复中的临床效果。方法:选择连续于我科就诊的57例上颌前牙区单颗牙种植修复患者,按照种植体长轴分为两组,A组26例长轴位于牙冠切端舌侧至舌隆突之间,上部结构设计为低边缘钛基台和舌侧开孔的氧化锆全瓷冠,戴牙前于体外预先粘结;B组31例长轴位于牙冠切端或唇侧,设计为个性化氧化锆基台和氧化锆全瓷冠,于口内常规粘结。戴牙当天和修复后12个月复诊时记录红色美学指数(pink esthetic score,PES),并于12个月复诊时检测种植体周围边缘骨吸收量(marginal bone loss,MBL)、改良菌斑指数(modified plaque index,mPI)、改良出血指数(modified sulcus bleeding index,mSBI)及各种机械并发症。结果:戴牙当天和复诊时两组PES差异均无统计学意义;修复后12个月,两组PES值均高于戴牙当天(P<0.05);两组MBL、mPI、mSBI值差异均无统计学意义。A组未发生机械并发症;B组出现2例钛基台与氧化锆穿龈结构之间松脱。结论:两种上部结构设计在上颌前牙区单颗牙种植修复中均能取得良好的效果,临床上可以根据病例具体情况选择。     

全下颌种植覆盖总义齿塑料牙与瓷牙能量缓冲作用的比较分析

目的：比较分析应用塑料牙与瓷牙对全下颌种植覆盖总义齿及其支持组织的能量缓冲作用。方法：应用三维有限元方法计算双后牙游离端加载下应用塑料牙或瓷牙时义齿各部分弹性变形能。结果：应用塑料牙比瓷牙的弹性变形能大，同时使其他部分的弹性变形能减少。结论：塑料牙比瓷牙能量缓冲作用大，有利于种植体及其支持组织的保护。