Effects of immediate loading with threaded hydroxyapatite-coated root-form implants on single premolar replacements: a preliminary report

PURPOSE: This prospective study evaluated the immediate loading of single, threaded, root-form implants placed in the maxillary premolar area. MATERIALS AND METHODS: Ten human subjects were included in this preliminary report. In all cases, a screw-retained temporary acrylic resin crown was placed immediately after implant surgery. The definitive screw-retained metal-ceramic crown was placed 6 months later. RESULTS: Standardized radiographs demonstrated 0.58, 0.73, 0.84, and 0.90 mm mean marginal bone loss at 1, 3, 6, and 12 months after implant surgery, respectively. Implant mobility was evaluated with the Periotest device. At the day of surgery, mean mobility was -3.3, while minor changes were observed thereafter: mean values of -3.77, -3.47, and -3.63 were recorded at 3, 6, and 12 months after implant surgery, respectively. Sulcus depth appeared relatively stable after the 3rd month when the implant platform was used as a reference. Recession of 0.43 mm was recorded between the 3rd and 12th month; when the depth of the peri-implant sulcus was measured from the implant platform, 0.1 mm of change was seen between the 3rd and 12th month. Probing depth measurements revealed that 3 months after implant placement, average probing depth was 3.60 mm, while at 12 months it was 3.20 mm. DISCUSSION: The peri-implant soft tissue parameters (bleeding on probing, probing depth, peri-implant soft tissue level), mobility, and marginal bone level appeared to be similar to findings of previous studies regarding the conventional 2-stage loading protocol. CONCLUSION: Results of the current study provided evidence that, under the condition of this investigation, single root-form implants can be immediately loaded when placed in the maxillary premolar area.     

两种固位方式下种植义齿周围组织情况及菌群分布的比较研究

目的：比较粘接固位与螺丝固位种植义齿修复后周围组织的健康情况及龈下菌群分布的差异。方法上下颌牙列缺损患者36例共68枚种植体,其中31枚采用螺丝固位修复体,37枚采用粘接固位修复体。分别于修复后第3个月、6个月、12个月复诊,检测种植义齿探诊深度（PD）、改良菌斑指数（mPLI）、改良出血指数（mSBI）等临床指标,比较种植体周围软组织健康状况,测量种植体边缘骨吸收（MBL）状况。采集种植体龈下菌群标本,比较两种固位方式修复后龈下菌群的差异。结果两组的mPLI、mSBI、PD、MBL在所有时间点差异均无统计学意义。在第3个月,螺丝固位组的种植义齿龈下厌氧菌总数高于粘接固位组（P<0.05）。在第6个月,螺丝固位组种植义齿龈下具核梭杆菌总数高于粘接固位组（P<0.05）。12个月时,两组龈下菌群数差异无统计学意义。结论螺丝固位与粘接固位两种固位方式对种植义齿周围软组织及边缘骨吸收的影响无显著差异。在修复后短期内,螺丝固位组厌氧菌总数、具核梭杆菌检出量较粘接固位组高,但在12个月时二者无明显差异。     

Immediate loading of osseotite implants: two-year results

The high success rate of dental implants has changed the quality of life for many patients. Immediate loading finds its application in some clinical cases and certainly adds another modality of treatment for the implant patient. Starting with a couple of implants placed in the mandible and immediately loaded within 72 hours after surgical placement with an overdenture, this concept evolved to immediately loading multiple implants in both the maxilla and the mandible. In this investigation, 11 consecutive patients were treated with 87 screw-shaped endosteal acid-etched, Osseotite implants (3i, Implant Innovations, Inc., Palm Beach Gardens, FL) between June 1998 and June 1999. Two mandibular and two maxillary cases received screw-retained provisional prostheses the day of surgery. Three mandibular and four maxillary cases were loaded 48 hours after surgery with the final screw-retained, porcelain-fused-to-metal prostheses. All implants were followed for 2 to 3 years. Follow-up consisted of clinical as well as radiographic examination. All implants were successful. There was no implant mobility or periimplant radiolucency. The bone level was measured at the 12th and 24th months. The average radiographic bone level from the implant platform to the first bone-to-implant contact was 0.654 mm at the 12th month and 0.946 mm at the 24th month. We conclude that a high success rate can be achieved when implants with a hybrid surface, machined/acid-etched, are immediately loaded within 48 hours after surgical placement in the maxilla and the mandible.     

Evaluation of immediately loaded mandibular four vertical versus tilted posterior implants supporting fixed detachable restorations without versus with posterior cantilevers

Background

Distally inclining posterior implants may be technically challenging in certain situations. The presence of a posterior cantilever can also exert unfavorable forces on supporting implants. The aim of the present study was to evaluate and compare peri-implant soft and hard tissues around 4 mandibular interforaminal implants having tilted posterior implants with posterior cantilevers, versus vertical implants, 2 in the interforaminal region and 2 in the first molar regions, without posterior cantilevers. All implants supported full-arch fixed detachable restorations opposing complete dentures.

Material and methods

A total of 80 implants were placed flapless in the mandibles of 20 edentulous participants. Four implants were placed for every participant, who were randomly assigned into 2 equal groups. Axial group implants were vertically aligned, with 2 implants in the interforaminal area and 2 in the molar area. Tilted group implants have 2 anterior axial and 2 posterior distally inclined implants. Interim screw-retained prostheses converted from pre-existing dentures were immediately fabricated and loaded on the same day of surgery. After awaiting period of 3 months, all participants received fixed detachable metal acrylic resin definitive restorations. A follow-up protocol of 3, 6, and 12 months was scheduled to assess the modified gingival index, modified plaque index, peri-implant probing depth, implant stability, and marginal bone level and bone density changes.

Results

No statistically significant differences (P?>?.05) were found in the modified gingival index, modified plaque index, peri-implant probing depth, implant stability, bone density, and marginal bone level between the axial and tilted implant groups after the 1-year follow-up period.

Conclusion

Placing 4 flapless immediately loaded implants in mandibular edentulous patients that supported full-arch fixed restorations provided high implant and prosthodontic success rates whether posterior implants were tilted with posterior cantilevers or vertically aligned without posterior cantilevers.

Trial registration: Pan African Clinical Trial Registry database, PACTR201907776166846. Registered 3 July 2019, www.pactr.org.

     

Peri-implant tissue response of immediately loaded, threaded, HA-coated implants: 1-year results

STATEMENT OF PROBLEM: Although high success rates have been reported with immediately loaded implants, the peri-implant tissue response has not been well documented. PURPOSE: This study evaluated implant success and peri-implant tissue response of immediately loaded, threaded, hydroxyapatite (HA)-coated root-form implants supporting mandibular bar overdentures with opposing conventional maxillary complete dentures in humans. MATERIAL AND METHODS: Five patients (3 men, 2 women; mean age 61 years) each received 4 HA-coated endosseous root-form implants in the interforaminal region in the mandible. The implants were rigidly splinted with a metal framework within 24 hours. The final EDS clip prosthesis was placed 1 to 2 weeks thereafter. The implants and peri-implant tissues were evaluated clinically and radiographically 0, 1, 3, 6, and 12 months after prosthesis placement. Data were analyzed with a repeated measures 1-way analysis of variance (P<.05). RESULTS: All implants were stable at the end of the observation period (mean Periotest value = -5.9 +/- 1.4). No peri-implant radiolucencies were noted, and no implants were lost. The mean marginal bone changes were -0.42 plus minus 0.34, -0.84 +/- 0.55, -1.14 +/- 0.80, and -1.16 +/- 0.89 mm at the 1-, 3-, 6-, and 12-month follow-ups, respectively (P<.001). Significant declines in the rates of marginal bone changes at each time interval were noted (P<.001). In addition, there were significant decreases in probing depth (P<.001) and plaque index (P<.001) but no significant difference in the frequency of bleeding upon probing (P=.64). CONCLUSION: Within the limitations of this study, the peri-implant tissue response of immediately loaded, HA-coated implants was favorable and comparable to that of conventional, delayed-loaded implants after 1 year.     

Two-stage IMZ implants and ITI implants inserted in a single-stage procedure. A prospective comparative study

The aim of this study was to evaluate the feasibility of using a two-stage implant system in a single-stage procedure and to study the impact of the microgap at crestal level and to monitor the microflora in the peri-implant area. Forty edentulous patients (Cawood & Howell class V-VI) participated in this study. After randomisation, 20 patients received two IMZ implants inserted in a single-stage procedure and 20 patients received two ITI implants. After 3 months, overdentures were fabricated, supported by a bar and clip attachment. A standardised clinical and radiographic evaluation was performed immediately after denture insertion and 6 and 12 months later. Twelve months after loading, peri-implant samples were collected with sterile paper points and analysed for the presence of putative periodontal pathogens using culture techniques. One IMZ implant was lost due to insufficient osseointegration. With regard to the clinical parameters at the 12 months evaluation, significant differences for plaque score and probing pocket depth (IMZ: mean 3.3 mm, ITI: mean 2.9 mm) were found between the two groups. The mean bone loss in the first year of functioning was 0.6 mm for both groups. Prevotella intermedia was detected more often in the ITI group (12 implants) than in the IMZ group (three implants). Porphyromonas gingivalis was found in three patients. In one of these patients an implant showed bone loss of 1.6 mm between T0 and T12. Some associations were found between clinical parameters and the target microorganisms in the ITI group. These associations were not present in the IMZ group. The short-term results indicate that two-stage implants inserted in a single-stage procedure may be as predictable as one-stage implants. The microgap at crestal level in nonsubmerged IMZ implants seems to have no adverse influence on the peri-implant microbiological colonisation and of crestal bone loss in the first year of functioning. The peri-implant sulcus can and does harbour potential periodontal pathogens without signs of peri-implantitis during the evaluation period of 1 year.     

Immediate placement and provisionalization of maxillary anterior single implants: 1-year prospective study

PURPOSE: This 1-year prospective study evaluated the implant success rate, peri-implant tissue response, and esthetic outcome of immediately placed and provisionalized maxillary anterior single implants. MATERIALS AND METHODS: Thirty-five patients (8 men, 27 women) with a mean age of 36.5 years (range 18 to 65) were included in this study. Thirty-five threaded, hydroxyapatite-coated implants were placed and provisionalized immediately after each failing tooth had been removed. The definitive restoration was placed 6 months later. The patients were evaluated clinically and radiographically at implant placement and at 3, 6, and 12 months after implant placement. RESULTS: At 12 months, all implants remained osseointegrated. The mean marginal bone change from the time of implant placement to 12 months was -0.26 +/- 0.40 mm mesially and -0.22 +/- 0.28 mm distally. No significant differences in the Plaque Index scores were noted at different time intervals. The mean midfacial gingival level and mesial and distal papilla level changes from pretreatment to 12 months were -0.55 +/- 0.53 mm, -0.53 +/- 0.39 mm, and -0.39 +/- 0.40 mm, respectively. All patients were very satisfied with the esthetic outcome and none had noticed any changes at the gingival level. DISCUSSION: Although marginal bone and gingival level changes were statistically significant from pretreatment to 12 months of follow-up, they were well within clinical expectations. CONCLUSION: The results of this study suggest that favorable implant success rates, peri-implant tissue responses, and esthetic outcomes can be achieved with immediately placed and provisionalized maxillary anterior single implants.     

Preservation of peri-implant soft and hard tissues using platform switching of implants placed in immediate extraction sockets: a proof-of-concept study with 12- to 36-month follow-up

PURPOSE: The purpose of this article is to evaluate the soft- and hard-tissue response to immediately placed implants. In addition, assessment was conducted of the soft tissue response to a transmucosal abutment which was narrower than the implant platform. MATERIALS AND METHODS: This study was conducted to evaluate 10 consecutively placed immediately loaded implants placed in extraction sockets in maxillae without compromised bone tissue. The infection control phase of periodontal therapy was completed in the areas of hopeless teeth prior to extraction. Implants with a 6-mm-platform diameter were placed immediately into the fresh extraction sockets. A provisional 4-mm-diameter transmucosal abutment was subsequently connected, and a provisional crown was adapted and adjusted for nonfunctional immediate positioning. Three months following implant placement, definitive prosthetic rehabilitation was performed. At the time of prosthesis insertion (baseline) and every 6 months thereafter, radiographic assessments, pocket probing depth (PPD), recession, and papilla height were measured. An image analysis software application was used to compare the radiographic bone crestal bone heights at the mesial and distal aspects of the implants. RESULTS: Nine patients with 10 sites were treated. Mean follow-up time was 22 months (range, 18 to 36 months). All 10 implants were found to be clinically osseointegrated. Software analysis of radiographic films showed a bone resorption of 0.78 +/- 0.36 mm. The mean values were significantly lower (P < or = .005) than a mean reference value of 1.7 mm. PPD did not exceed 3 mm in any site (average, 2.8 mm). Rather than recession, there was a mean gain in the buccal margin of 0.2 mm and a mean gain in papilla height of 0.25 mm. CONCLUSION: This proof-of-concept study suggests that immediate loading with platform switching can provide peri-implant hard tissue stability with soft tissue and papilla preservation. (Case Series)     

Single-blind randomized clinical trial to evaluate clinical and radiological outcomes after one year of immediate versus delayed implant placement supporting full-arch prostheses

Purpose: To evaluate and compare peri-implant health, marginal bone loss and success of immediate and delayed implant placement for rehabilitation with full-arch fixed prostheses. Material and Methods: The present study was a prospective, randomized, single-blind, clinical preliminary trial. Patients were randomized into two treatment groups. In Group A implants were placed immediately post-extraction and in Group B six months after extraction. The following control time-points were established: one week, six months and twelve months after loading. Measurements were taken of peri-implant crevicular fluid volume, plaque index, gingival retraction, keratinized mucosa, probing depth, modified gingival index and presence of mucositis. Implant success rates were evaluated for the two groups. The study sample included fifteen patients (nine women and six men) with a mean average age of 63.7 years. One hundred and forty-four implants were placed: 76 placed in healed sites and 68 placed immediately. Results: At the moment of prosthetic loading, keratinized mucosa width and probing depth were higher in immediate implants than delayed implants, with statistically significant differences. However, after six and twelve months, differences between groups had disappeared. Bone loss was 0.54 ± 0.39 mm for immediate implants and 0.66 ± 0.25 mm for delayed implants (p=0.201). No implants failed in either group. Conclusions: The present study with a short follow-up and a small sample yielded no statistically significant differences in implant success and peri-implant marginal bone loss between immediate and delayed implants with fixed full-arch prostheses. Peri-implant health showed no statistically significant differences for any of the studied parameters (crevicular fluid volume, plaque index, gingival retraction, keratinized mucosa, probing depth, modified gingival index and presence of mucositis) at the twelve-month follow-up. Key words:Immediate implants, delayed implants, peri-implant health, success rate.     

口腔种植体边缘骨吸收的临床疗效评价

目的:观察口腔种植牙修复牙列缺损的临床应用效果。方法:收集2009年1月~2014年1月种植义齿修复牙列缺损47例患者,共Anthogyr系统94颗种植体。随访3~36个月,均对其在植入后即刻、3个月、6 个月、12 个月、(>12)个月拍摄口腔曲面断层片,测量种植体周围骨吸收水平,并运用SPSS17.0进行统计分析。结果:种植体不同时间段骨吸收量之间有统计学差异;种植体植入后3个月与6个月之间,6个月与(>12)个月之间,12个月与(>12)个月之间的种植体周围骨吸收量有非常显著性意义(P<0.05)。结论:种植体植入6个月时周围骨吸收量最大。     

后牙区螺丝固位与黏结固位种植义齿修复效果的比较研究

目的探讨后牙区螺丝同位与黏结固位种植固定义齿临床修复效果的差异。方法选择上下颌后牙区牙列缺损患者42例共70枚种植体．其中24枚采用螺丝固位修复体．46枚采用黏结周位修复体。分别于修复后1年复诊．检测种植体周围边缘骨吸收量、改良菌斑指数（mPLI）、改良出血指数（mSBI）等临床指标以及患者对种植义齿的美观满意度。结果螺丝固位组及黏结固位组平均种植体周围边缘骨吸收量分别为0．78mm和0．68mm：螺丝组与黏结组mPLI平均水P50均为1，mSBI平均水平P50亦均为1：两组美观满意度平均得分P50为1。统计结果显示螺丝固位组与黏结固位组间种植体周围边缘骨吸收量、mPLI、mSBI以及患者满意度的差异均无统计学意义（P〉0．05）。结论后牙区螺丝固位与黏结固位种植义齿短期临床修复效果差异无统计学意义。     

Full Arch Restoration with Computer-Assisted Implant Surgery and Immediate Loading in Edentulous Ridges with Dental Fresh Extraction Sockets. One Year Results of 10 Consecutively Treated Patients

There is a growing need for patients to be rehabilitated with a fixed, implant-supported prosthesis immediately after surgery. The present study aims to describe the results of a modified prosthetic and surgical protocol of computer-assisted implant insertion and immediate loading in edentulous jaws with extraction sockets. Ten patients were consecutively treated with a modified computer assisted implant surgery protocol and screw-retained provisional metal-acrylic prosthesis prepared ahead of surgery and delivered immediately. Overall, 60 implants (Nobel Replace Tapered Groovy) were inserted, of which 22 were inserted in fresh extraction sockets. Definitive prosthesis was delivered after 6–12 months. Outcome measures were radiographic marginal bone-level changes, survival of implants, and patient satisfaction. The follow-up period was of at least 12 months. All the patients felt comfortable and none withdrew from the study. No implants were lost, resulting in a cumulative survival rate of 100 %. Radiological estimation showed a mean peri-implant marginal bone loss of 1.4 ± 0.3 mm. No other complications, biological or mechanical, were recorded. In all cases, patients appeared to be very satisfied with the aesthetic and function. Within the limitations of this study, our data seem to validate this surgical and prosthetic protocol with valid functional and aesthetic results when applied in selected cases.     

2种不同种植体植入对种植体周围软组织的影响

目的: 研究2种种植体对种植体周围软组织的影响。方法: 选择2020年12月—2021年2月普陀区眼病牙病防治所收治的单颗后牙缺失且需行种植修复的患者40例,其中植入骨水平种植体10例,软组织水平种植体30例。在完成种植冠修复当天、3个月、6个月及12个月时比较2组种植体的探诊深度,检测种植体龈沟液中天冬氨酸转氨酶（AST）和碱性磷酸酶（ALP）水平。采用SPSS 17.0软件包对数据进行统计学分析。结果: 修复完成当天、3个月、6个月及12个月,软组织水平种植体的探诊深度和ALP水平均显著低于骨水平种植体（P<0.05）。其中修复完成当天,软组织水平种植体的AST显著低于骨水平种植体（P<0.05）。随着时间增加,骨水平种植体龈沟液中的AST迅速降低,最后与软组织水平种植体接近（P>0.05）。结论: 尽管骨水平种植体和软组织水平种植体均具有良好的临床使用效果,但软组织水平种植体周围的软组织表现出更好的稳定性。     

Probe penetration in periodontal and peri-implant tissues. An experimental study in the beagle dog

BACKGROUND: Today, periodontal probing is the best diagnostic tool to assess the health status and attachment level of periodontal tissues. There are, however, doubts as to whether the same method could be used for implants. Experiments comparing peri-implant and periodontal probing provide conflicting results. The impact and interpretation of peri-implant probing are still not sufficiently known. PURPOSE: The purpose of the present study was to further analyze the histological level of probe penetration in healthy periodontal and peri-implant tissues. MATERIAL AND METHODS: In four beagle dogs, all mandibular premolars were extracted. Three months later, four experimental non-submerged implants were placed in each edentulous premolar region. Six months later, probing depth was determined at the buccal aspect at two of the implants and at the bilateral first mandibular molars. A pressure-controlled probe with a diameter of 0.4 mm and 0.2 N probing force was used. Following the probing depth assessment, a metal periodontal probe tip was inserted into the previously measured depth and attached to the implants and teeth using a composite material. Block biopsies were obtained and prepared for histometric examinations. RESULTS: The findings showed that probing resulted in similar probe extension at implants and teeth, that the probe extension corresponded to the extension of the barrier epithelium and that the distance between the probe tip and the bone was about 1 mm in both peri-implant and periodontal tissues. CONCLUSIONS: This experiment showed that under healthy conditions, the probe tip penetration in the soft tissues at teeth and implants is similar when a probing force of 0.2 N is used. Probing around implants using a moderate force is a valuable diagnostic tool in the maintenance of implant patients.     

Immediate restoration of implants placed into fresh extraction sockets for single-tooth replacement: a prospective clinical study

The aim of the present clinical study was to evaluate the placement of transmucosal implants into fresh extraction sockets and their immediate restoration with temporary crowns. A series of 22 cases with a 12-month follow-up is presented. Twenty-two patients (15 women and 7 men; mean age 39 years) who needed a single tooth replaced because of vertical or horizontal root fracture, caries, endodontic lesions, or periodontal disease were treated with immediate postextraction implant placement. The implant was then restored with a screw-retained prosthetic restoration within 24 hours. Radiographic assessments were made at baseline and 12 months after implant placement. Clinical parameters, such as plaque score, mucositis score, probing attachment level, mucosal margin position, variation of gingival level, and variation of papilla position, were also measured at baseline and after 12 months of follow-up. At 12 months, no implants had failed. Radiographic examination revealed mean bone resorption of 0.5 mm at 12 months compared to baseline. The mean variation of gingival level, compared to the neighboring teeth, was -0.75 mm. Probing attachment levels were 0.79, 0.45, and 0.54 mm at proximal, buccal, and lingual sites, respectively. The values for the mucosal margin position were 2.9, 2.2, and 2.4 mm at proximal, buccal, and lingual sites, respectively. Regarding variation of papilla position, according to Jemt's index, 27 papillae presented with a score of 2 (61%) and 17 with a score of 3 (39%). An examination of oral hygiene and peri-implant soft tissue conditions at the 12-month follow-up visit revealed an overall frequency of plaque-carrying implant surfaces of 13%. Furthermore, mucositis (score 2) was not observed at any of the peri-implant units. Primary implant stability did not significantly increase over time. The immediate restoration of dental implants placed into fresh extraction sockets was shown to be a safe and predictable procedure. The success rate and radiographic and clinical results were comparable to those obtained following the standard protocol. Within the limits of the present investigation, immediate restoration of single-tooth implants placed in fresh extraction sockets can be considered a valuable option to replace a missing tooth. However, long-term clinical trials are needed to confirm the present results.     

Peri-implant bone changes following tooth extraction, immediate placement and loading of implants in the edentulous maxilla

The aim of this study was to clinically and radiographically evaluate peri-implant bone level changes after rehabilitation of a fully edentulous maxilla by placement of six implants in either fresh extraction sites or healed edentulous ridges up till 18 months after implant placement. Twenty patients with a terminal dentition in the maxillae (11 men, 9 women) received a total of 120 OsseoSpeed implants; 118 implants could be loaded immediately of which 59 were placed in extraction sockets and 59 were placed in healed sites. Within 24 h after surgery, all patients received a chairside-assembled, fibre-reinforced temporary fixed prosthetic reconstruction in occlusion. Six months post-surgery, final screw-retained CoCr (15) or Ti (5) computer numerical control-milled and acrylic-veneered frameworks were placed directly at implant level without interposing abutments. Intraoral radiographs were taken 6 and 18 months after implant placement. Implant survival rate was 100%. Mean marginal bone level was located on average -0.35 mm below the reference point (standard deviation 0.29, range -1.20 to +0.02 mm) 18 months after loading. Whether implants were placed in healed bone sites or fresh extraction sockets did not significantly affect the bone level changes. Furthermore, the use of either CoCr or Ti at the implant level did not significantly affect marginal bone loss. Within the limits of this prospective clinical trial, results seem to indicate that immediate placement and occlusal loading of five to six implants in the edentulous maxilla can be carried out successfully. Whether or not those implants are placed in fresh extraction sockets does not seem to alter the outcome. The present data show a successful 1-year outcome of a treatment protocol involving tooth extraction immediately combined with implant placement and loading.     

Evaluation of peri-implant bone loss around platform-switched implants

This clinical and radiographic prospective study evaluated bone loss around two-piece implants that were restored according to the platform-switching protocol. One hundred thirty-one implants were consecutively placed in 45 patients following a nonsubmerged surgical protocol. On 75 implants, a healing abutment 1 mm narrower than the implant platform was placed at the time of surgery. On the remaining implants, a healing abutment of the same diameter as the implant was inserted. All implants were positioned at the crestal level. Clinical and radiographic examinations were performed prior to surgery, at the end of surgery, 8 weeks after implant placement, at the time of provisional prosthesis insertion, at the time of definitive prosthesis insertion, and 12 months after loading. The data collected showed that vertical bone loss for the test cases varied between 0.6 mm and 1.2 mm (mean: 0.95 +/- 0.32 mm), while for the control cases, bone loss was between 1.3 mm and 2.1 mm (mean: 1.67 +/- 0.37 mm). These data confirm the important role of the microgap between the implant and abutment in the remodeling of the peri-implant crestal bone. Platform switching seems to reduce peri-implant crestal bone resorption and increase the long-term predictability of implant therapy.     

Immediate function with fixed implant-supported maxillary dentures: a 12-month pilot study

STATEMENT OF PROBLEM: Immediate occlusal loading of dental implants in the edentulous mandible has proven to be an effective, reliable, and predictable procedure. There is little long-term data available on similar treatments in the edentulous maxilla. PURPOSE: The purpose of this study was to evaluate the 12-month implant survival after immediate loading of 4 to 6 implants with fixed screw-retained prostheses in edentulous maxillae. MATERIAL AND METHODS: Twenty-one patients, edentulous or with remaining teeth to be extracted in the maxilla, received 4 to 6 implants (n=111). The patients were restored with screw-retained fixed provisional prostheses supported by palladium-alloy frameworks within 24 hours after surgery. Insertion torques for implants were at least 40 Ncm. Implants, grouped as tapered or cylindrical screws, were placed in healed bone or extraction sockets. Implants were also classified as either vertical or off-angle. Definitive prostheses were placed after a mean healing time of 18 weeks. Radiographic examinations were made at the time of placement of provisional prostheses and 12 months later. Between-groups bone resorption was compared using 2-way ANOVA (alpha=.05). RESULTS: The mean follow-up time for all of the patients was 20 months (range, 13 to 28 months). The cumulative implant survival rate at the 12-month follow-up visits (after surgery) was 92.8%; the prostheses survival rate was 100%. No significant differences were found between the survival of tapered or cylindrical screw-type implants placed in postextraction sockets versus those in healed edentulous sites or between vertical and off-angle placed implants. Eight implants failed during the first 3 months, 5 of which were the most distal implants. The mean reduction in marginal bone height over the 12-month observation period was 0.84 mm (CI 95%; 0.68-0.99 mm). CONCLUSIONS: In this study with 12-month follow-up, 4 to 6 implants were sufficient to successfully support fixed implant screw-retained prostheses in the edentulous maxillae of 21 patients.     

Treatment of peri-implantitis by local delivery of tetracycline. Clinical, microbiological and radiological results

The purpose of this study was to investigate the clinical, microbiological and radiological effects of peri-implantitis therapy by local delivery of tetracycline. In 25 partially edentulous patients, 30 implants with radiographic evidence of circumferential bone loss, and peri-implant probing depths > or =5 mm were treated with polymeric tetracycline HCl-containing fibers. Clinical and microbial parameters were recorded at baseline, and 1, 3, 6, and 12 months (M) after treatment. Standardized radiographs were obtained at baseline, M3, and one year after treatment. Two patients were discontinued from the study after 180 days because of persisting active peri-implantitis with pus formation. The remaining subjects showed a significant decrease of mean peri-implant probing depth from 6.0 to 4.1 mm (M1, P<0.001), which was maintained over 12 months. In comparison to baseline, the bleeding tendency was significantly reduced after one month, and thereafter (P<0.001). No significant recession of the mucosal margin was noted. The radiologically determined distance from the shoulder of the implant to the bottom of the bony defect decreased slightly, but not significantly, from 5.2 to 4.9 mm. At M1, M3 and M6, mean total anaerobic cultivable bacterial counts were significantly lower than at baseline (P<0.001). A significant decrease in frequency of detection was noted for Prevotella intermedia/nigrescens, Fusobacterium sp., Bacteroides forsythus, and Campylobacter rectus (P<0.01). Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Eikenella corrodens had very low baseline frequencies that could not be significantly suppressed further. In conclusion, therapy of peri-implantitis by local delivery of tetracycline had a positive effect on clinical and microbiological parameters.     

即刻种植种植体周围骨缺损的Beagle犬动物模型建立

目的:评估即刻种植后种植体周围骨缺损植骨与否对骨结合的影响,建立一种符合即刻种植种植体周围骨缺损特点的动物模型。方法:以成年Beagl e犬为实验动物,拔除犬双侧下颌P2、P3、P4牙。于远中根拔牙窝的远中距牙根间隔5-6mm处预备种植窝,即刻植入种植体。植入种植体后保证沿下颌骨长轴向骨缺损范围达3-4mm。骨缺损区不植入骨粉,直接用胶原膜覆盖为实验组。骨缺损区植入骨粉并覆盖胶原膜为对照组。于术后3个月末处死动物取材,进行组织学观察。结果:X线观察:实验组与对照组缺损处到3个月时均被新生骨充填。组织切片染色镜下观察:实验组与对照组骨缺损处可见大量骨细胞,骨改建基本完成。结论:种植体与拔牙窝内壁之间的3-4mm范围骨间隙即使不植骨,也会有新骨生成、并且可以与种植体表面发生骨结合。成功构建了与临床即刻种植骨缺损相似,并可作为研究即刻种植骨界面骨性结合的实验动物模型。