愈合期埋植型和非埋植型种植体周围牙槽骨吸收情况观察

目的：观察比较愈合期两段式埋植型和非埋植型种植体周围牙槽骨吸收情况是否存在差异。方法：收集种植义齿修复下颌后牙区牙体缺损患者44例共94颗,其中54颗两段式埋植型Frialit-2种植体和40颗两段式非埋植型ITI种植体,根据种植体植入术后和愈合后数字化全景X线片来进行种植体周围牙槽骨高度的测量。结果：显示愈合期两段式埋植型Frialit-2种植体和非埋植型ITI种植体周围骨吸收值不存在统计学差异（p=0．667〉0．05）。结论：在本实验条件下,愈合期埋植型和非埋植型种植体周围牙槽骨骨吸收改变与种植体的植入方式无关。     

Bone level alterations at implants placed in the posterior segments of the dentition: outcome of submerged/non-submerged healing. A 5-year multicenter, randomized, controlled clinical trial

Objective: To determine if longitudinal bone level change at Astra Tech^? implants placed in the posterior part of the dentition was influenced by the healing conditions provided following implant placement, i.e., submerged or non‐submerged healing. Material and methods: Eighty‐four patients and 115 fixed partial dentures (FPDs or cases) entered the study. The cases were randomized into two implant installation groups: initially non‐submerged (group A) or initially submerged (group B) implants. Three hundred and twenty‐four implants were installed (group A=153; group B=171): 145 in the maxilla and 179 in the mandible. Radiographs from the implant sites were obtained at FPD insertion (baseline) and subsequently every 12 months. In the radiographs, the position of the marginal bone at the mesial and distal aspects of the implants was determined and the radiographic (Rx) bone level change over time was calculated. Results: Seven implants failed to integrate (four in group A and three in group B). During the 5 years of monitoring, three implants had to be removed and 35 implants were lost to follow‐up. The Rx bone level alteration that occurred during year 1 was 0.02±0.38 mm in group A and 0.17±0.51 mm in group B. During the subsequent 4 years there was some further Rx bone loss in group B (0.02±0.62 mm), while in group A there was some gain of bone (0.07±0.5 mm). Conclusion: The peri‐implant bone level change and number of biological complications that took place during the 5 years was small and unrelated to the surgical protocol used for implant placement.     

Bone regeneration at implants with turned or rough surfaces in self-contained defects. An experimental study in the dog

BACKGROUND: Marginal hard tissue defects present at implants with a rough surface can heal with a high degree of bone fill and osseointegration. The healing of similar defects adjacent to implants with a smooth surface appears to be less predictable. OBJECTIVE: The aim was to compare bone healing at implants with turned or rough surface topographies placed in self-contained defects using either a submerged or non-submerged installation technique. MATERIAL AND METHODS: Six dogs were used. Three months after tooth extraction four experimental sites were prepared for implant installation in both sides of the mandible. The marginal 5 mm of the canal prepared for the implant was widened. Thus, following implant placement a circumferential gap occurred between the bone tissue and the implant surface that was between 1 and 1.25 mm wide. In each side of the mandible two implants with a turned surface and two implants with a rough surface were installed. The implants in the right side were fully submerged, while a non-submerged technique was applied in the left side. The animals were sacrificed 4 months later, block biopsies of each implant site were dissected and ground as well as paraffin sections were prepared. RESULTS: The marginal defects around rough surface implants exhibited after 4 months of healing substantial bone fill and a high degree of osseointegration following either the submerged or the non-submerged installation technique. Healing at turned implants was characterized by incomplete bone fill and the presence of a connective tissue zone between the implant and the newly formed bone. The distance between the implant margin (M) and the most coronal level of bone-to-implant contact (B) at implants with a rough surface was 0.84+/-0.37 mm at submerged and 0.90+/-0.39 mm at non-submerged sites. The distance M-B at implants with a turned surface was 3.39+/-0.52 mm at submerged and 3.23+/-0.68 mm at non-submerged sites. The differences between the rough and turned implants regarding the length of distance M-B were statistically significant (paired t-test). CONCLUSION: Osseointegration at implants placed in sites with marginal defects is influenced by the surface characteristics of the implant.     

Oral rehabilitation with implant-supported fixed partial dentures in periodontitis-susceptible subjects. A 5-year prospective study

BACKGROUND: Comparatively few studies with at least 5 years of follow-up are available that describe the use of implants in prosthetic rehabilitation of partially edentulous patients. Randomized, controlled clinical studies that evaluated the effect of different surface designs of screw-shaped implants on the outcome of treatment are also sparse. OBJECTIVE: To determine, in a prospective randomized, controlled clinical trial, the outcome of restorative therapy in periodontitis-susceptible patients who, following basic periodontal therapy, had been restored with implants with either a machined- or a rough-surface topography. MATERIAL AND METHODS: Fifty-one subjects (mean age, 59.5 years), 20 males and 31 females who, following treatment of moderate-to-advanced chronic periodontitis, required implant therapy for prosthetic rehabilitation were recruited. Seventeen of the patients were current smokers. Following the active treatment, all subjects were included in an individually designed maintenance program. A total of 56 fixed partial dentures (FPDs) and a total of 149 screw-shaped, and self-tapping implants (Astra Tech implants) -- 83 in the maxilla and 66 in the mandible -- were installed in a two-stage procedure. Each patient received a minimum of two implants and by randomization every second implant that was installed had been designed with a machined surface and the remaining with a roughened Tioblast surface. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographical examinations were performed following FPD connection and once a year during a 5-year follow-up period. The analysis of peri-implant bone-level alterations was performed on subject, FPD and implant levels. RESULTS: Four patients and four FPDs were lost to the 5 years of monitoring. One implant (machined surface) did not properly integrate (early failure), and was removed at the time of abutment connection. Three implants were lost during function and a further eight implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 5.9% (subject level), 5.3% (FPD level) and 2.7% (implant level). Radiographic signs of loss of osseointegration were not found at any of the implants during the 5-year observation period. During the first year in function there was on average 0.33 (SD, 0.61) mm loss of peri-implant marginal bone on the subject and FPD levels and 0.31 (0.81) mm on the implant level. During the subsequent 4 years, the peri-implant bone-level alterations were small. The calculated annual change in peri-implant bone level was -0.02 (0.15) on subject and FPD levels and -0.03 (0.20) on the implant level. Thus, the mean total bone-level change over the 5-year interval amounted to 0.41 mm on all three levels of analysis. In the interval between baseline and 5 years, the machined and the Tioblast implants lost on average 0.33 and 0.48 mm, respectively (p>0.05). CONCLUSION: The present randomized, controlled clinical trial that included partially edentulous periodontitis-susceptible subjects demonstrated that bone loss (i) during the first year of function as well as annually thereafter was small and (ii) did not vary between implants with machined- or rough-surface designs.     

On the role of number of fixtures, surgical technique and timing of loading

AIMS: The aims of this thesis were to analyze reduced number of implants supporting full arch fixed mandibular prostheses and fixed partial dentures (FPDs), non-submerged healing and early loading in the edentulous mandible. A further aim was to evaluate fit of Computer Numerical Controlled (CNC) milled I-Bridge frameworks. MATERIAL & METHODS: Paper I. One hundred and nineteen patients rehabilitated with full arch mandibular prostheses supported by four implants were evaluated after a mean follow-up of 4.4 years. Paper II. A total of 178 patients provided with FPDs supported by two (n=92) or three implants (n=122) of whom 123 were evaluated after a mean follow-up of 9.4 years. Paper III. Early and delayed loading of full arch mandibular prostheses were evaluated in 109 patients, 54 with delayed loading and 55 with early loading, with a mean follow-up of 3.6 years. Paper IV. Submerged and non-submerged implant placement for supporting fixed prostheses in the edentulous mandible were evaluated after five years in 29 patients. Paper V. The precision of fit of CNC-milled I-Bridge frameworks was evaluated using two different implant systems. RESULTS: Paper I. The five-year cumulative survival rate (CSR) for implants was 99.1% and for prostheses 100%. Mean bone loss from baseline to five-year follow-up was 0.5 mm. No indication could be found that the number of supporting implants influenced the prosthetic complications. Paper II. The five-year implant and prosthesis CSR was 97.7% for two-implant supported FPDs and 97.3% for three-implant supported FPDs. Mean bone loss at five years was 0.4 mm. Significantly more prosthetic and abutment screw loosening were seen in two-implant supported FPDs. Paper III. Five-year CSR for implants was 94.4% and 92.5% for prostheses in early loading, and 97.9% and 98.0% in the delayed loading group. More prostheses needed adjustment or replacement in the early group, but patients treated with early loading were more pleased with the treatment procedure. Paper IV. Five-year CSR survival rate was 99.4%. Three implants fractured in one patient. Mean bone loss at five years was 0.7 mm in submerged implants and 0.5 mm in non-submerged implants. Paper V. All frameworks demonstrated clinically acceptable fit with mean distortion values within 23 microm (x-axis), 26 microm (y), 4 microm (z- axis) and 34 microm (3-D) for all frameworks. Control frameworks displayed greater levels of distortion than frameworks produced in a strict test situation. CONCLUSION: A reduction of the number of supporting implants to four implants in full arch mandibular prostheses and two implants in three unit FPDs in partial edentulous jaws resulted in the same clinical outcome as when more implants are used. Non-submerged implant placement in the edentulous mandible was as predictable as submerged, but early loading of implant-supported mandibular prostheses incurred more prosthetic complications. Computer numerical controlled milled frameworks presented levels of precision of fit within limits considered to be clinically acceptable and superior to earlier published results on cast frameworks.     

Feasibility and influence of the microgap of two implants placed in a non-submerged procedure: a five-year follow-up clinical trial

BACKGROUND: The aim of this study was to evaluate the feasibility of using a two-piece implant system in a non-submerged procedure and to study the impact of the microgap between the implant and abutment. METHODS: Sixty edentulous patients (Cawood Class V-VI) participated in this study. After randomization, 20 patients received two two-piece implants placed in a non-submerged procedure, 20 patients received two two-piece implants placed in the traditional submerged procedure, and 20 patients were treated with two one-piece dental implants placed in the traditional non-submerged procedure. The implants were placed in the mandible for overdenture treatment. A standardized clinical evaluation was performed and radiographs were taken immediately after denture insertion and yearly up to 5 years. Peri-implant samples were collected 12, 36, and 60 months after loading with sterile paper points and analyzed for the presence of putative periodontal pathogens using culture techniques. RESULTS: One two-piece implant of the non-submerged group and one two-piece implant of the submerged group were lost after 6 and 12 months, respectively. After 5 years of functioning, no significant clinical, radiological, or microbiological differences were found between the three groups. No association was found between the level of the microgap and the amount of bone loss. CONCLUSIONS: The results of this study indicate that dental implants designed for a submerged implantation procedure can also be used in a non-submerged procedure and may be as predictable as when used in a submerged procedure or as one-piece implants. The microgap at the crestal level in two-piece implants does not appear to have an adverse effect on the amount of peri-implant bone loss.     

Bone reactions to longstanding functional load at implants: an experimental study in dogs

Objectives: The aims of the present investigation were (i) to study marginal bone level alterations following implant installation, abutment connection and functional loading and (ii) to analyse bone tissue reactions to functional load. Material and Methods: Six beagle dogs, about 1‐year old, were used. All mandibular pre‐molars were extracted. Three months later four implants of the Astra Tech Implants^® Dental System were installed in one side of the mandible and four standard fixtures of the Brånemark System^® were placed in the contralateral side of the mandible. Abutment connection was performed 3 months later and a plaque control programme was initiated. Three months after abutment connection fixed partial dentures (FPDs) made in gold were cemented to the maxillary canines and pre‐molars. FPDs were also connected to the three posterior implants in each side of the mandible, while the mesial implant in each side was used as an unloaded control. Radiographs were obtained from all implant sites following implant installation, abutment connection and FPD placement. Ten months after the FPD placement the radiographic examination was repeated. The animals were sacrificed and biopsies from all implant sites were obtained and prepared for histological analysis. Results: The radiographic analysis revealed that largest amount of bone loss occurred following implant installation and abutment connection and that this loss was more pronounced at Brånemark than at Astra implants. The bone level alterations that were observed at implants exposed to 10 months of functional load in both implant systems were small and did not differ from control sites. The histological analysis revealed that implants exposed to functional load exhibited a higher degree of bone‐to‐implant contact than control implants in both implant systems. Conclusion: It is suggested that functional load at implants may enhance osseointegration and does not result in marginal bone loss.     

Influence of platform switching on crestal bone changes at non-submerged titanium implants: a histomorphometrical study in dogs

OBJECTIVES: The aim of the present study was to investigate histomorphometrically the influence of platform switching on crestal bone changes at non-submerged wide-body titanium implants in a dog model. MATERIAL AND METHODS: One-stage insertion of sand-blasted and acid-etched screw-type implants with either matching (CAM) or smaller-diameter healing abutments (CPS) were randomly assigned to the lower jaws of nine beagle dogs. The animals were killed after 7, 14, and 28 days of non-submerged healing. Dissected blocks were processed for histomorphometrical analysis. Measurements were made between the implant shoulder (IS) and:--the apical extension of the long junctional epithelium (aJE), --the most coronal level of bone in contact with the implant (CLB), and --the level of the alveolar bone crest (BC). RESULTS: At 7, 14, and 28 days, the mean IS-aJE values were significantly the lowest at CPS implants. However, after 28 days of healing, both groups revealed significantly increased mean IS-BC values at the buccal aspect of the alveolar bone. The difference in IS-CLB and IS-BC between groups was not significant. CONCLUSIONS: Within the limits of the present study, it was concluded that both CAM and CPS implants revealed crestal bone-level changes after 28 days of healing.     

Immediate loading of implants in the edentulous maxilla

The overall aim of this thesis was to investigate different therapeutic strategies in treatment of the edentulous maxilla with dental implants and their importance for treatment outcome. The introduction of one-stage surgery, in place of two-stage surgery, was a paradigm shift in the area of implant treatment since submerged implant healing underneath the mucosa was considered a prerequisite for healing in the original concept. The advantages of a one-stage method are that a second surgery is unnecessary, costs are lower, and patients complain less about the surgical procedures. The development of implant treatment, regardless of whether it is performed in the mandible or the maxilla, strives to shorten the period from implant placement to implant loading. For the edentulous patient--due to esthetic, economical, or psychological reasons--shortening this time and thus avoiding a long period of wearing a transitional removable prosthesis is advantageous. Use of conventional one-stage surgery makes possible and is a prerequisite for immediate loading of implants. Successful treatment outcome has been demonstrated for immediate loading of implants in the mandible, but documentation of the method in the maxilla is still sparse. Two prospective clinical studies compared (i) one- and two-stage surgery and (ii) immediate and conventional loading in patients consecutively treated in the edentulous maxilla with implant-supported fixed prostheses. The first study found that the cumulative survival rate (CSR) after one-stage surgery performed according to a conventional protocol was consistent with two-stage protocol CSRs reported in previous studies. The second study evaluated an immediate loading protocol that provided patients with interim fixed prostheses within 24 hours after implant placement. A comparison of the studies found no significant difference in CSRs. But it was found that when a conventional protocol was used, transitional removable prostheses could traumatize the bone-implant interface during healing by adverse loading on the implants, which pierced the mucosa. Moreover, splinting the implants immediately after surgery with an interim fixed prosthesis might protect them from adverse loading. In a finite element analysis comparing uncoupled and splinted implants--imitations of the clinical situations in the two studies--splinted implants drastically reduced stresses in the bone tissue surrounding the implant, which might facilitate bone healing. Two factors considered important for a successful treatment outcome, especially when loading implants immediately, are (i) jawbone quality and (ii) primary implant stability at placement. In implant literature, bone quality is generally equivalent to bone density. Results of the third clinical study in this thesis indicate that use of computed tomography with calculations of bone mineral density can be a useful tool in bone tissue evaluation before implant placement. After 1 year of loading, changes in marginal bone level, compared to baseline, did not differ between implants that were stable and implants that were not stable at placement. The results of this thesis do not strengthen earlier recommendations that immediate and early loading is a treatment alternative that can be considered only in jaws with good bone quality. In conclusion, immediate loading with interim fixed prostheses in the edentulous maxilla is a viable treatment alternative. Splinting of implants seems to be important in immediate loading, especially when bone density is low.     

The peri‐implant hard and soft tissues at different implant systems. A comparative study in the dog.

The aim of the present experiment was to study the marginal peri-implant tissues at intentionally non-submerged (1-stage implants) and initially submerged and subsequently exposed implants (2-stage implants). 5 beagle dogs, about 1-year-old, were used. 3 months after the extraction of the mandibular premolars, fixtures of the Astra Tech Implants Dental System®, the Brånemark System® and the Bonefit®-ITI System were installed. In each mandibular quadrant, 1 fixture of each implant system was installed in a randomised order. The installation procedure followed the recommendations given in the manuals for each system. Thus, following installation, the bone crest coincided with the fixture margin of the Astra Tech Implants Dental System® and the Brånemark System®, whereas the border between the plasma sprayed and the machined surface of the Bonefit®-ITI implant system was positioned at the level of the bone crest. Following a healing period of 3 months, abutment connection was carried out in the 2-stage systems (the Astra Tech Implants Dental System® and the Brånemark system®). A 6-month period of plaque control was initiated. The animals were sacrificed and biopsies representing each implant region dissected. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The mucosal barrier which formed to the titanium surface following 1-stage and 2-stage implant installations comprised an epithelial and a connective tissue component, which for the 3 systems studied, had similar dimensions and composition. The amount of lamellar bone contained in the peri-implant region close to the fixture part of the 3-implant systems was almost identical. It is suggested that correctly performed implant installation may ensure proper conditions for both soft and hard tissue healing, and that the geometry of the titanium implant seems to be of limited importance.     

Amine fluoride/stannous fluoride and chlorhexidine mouthwashes as adjuncts to single-stage dental implants: a comparative study

BACKGROUND: The growing popularity of non-submerged dental implants in recent years requires a greater emphasis on microbial plaque control. Chlorhexidine (CHX), the most commonly used mouthwash in implant surgery, is sometimes associated with tooth staining and alteration in taste perception. Amine fluoride/stannous fluoride (AmF/SnF2) mouthwash has been shown to have anti-infective properties; however, it has not been tested as an adjunct anti-infective means in non-submerged dental implants. The purpose of this trial was to compare AmF/SnF2 and CHX mouthwashes as adjuncts to single-stage dental implants. METHODS: Thirty-three patients aged 34 to 79 (mean 54.30 +/- 8.69 SD) requiring dental implants were accepted into the study. Following comprehensive periodontal therapy patients received one to three non-submerged dental implants (maxilla: 17; mandible: 45; anterior: 3, posterior: 59). After surgery patients were given analgesics and antibiotics as well as 2,400 ml of coded mouthwash bottles previously randomized between the two above mentioned formulations. Clinical and radiographic parameters were recorded at baseline and 3 and 12 months post-surgery. RESULTS: Twelve-month survival rates were 100% and 92.9% for the AmF/SnF2 and CHX groups, respectively. Compliance was slightly higher in the AmF/SnF2 group (84.35% +/- 3.39% versus 78.15% +/- 4.59% SE) but statistically similar. There was no statistically significant difference between the AmF/SnF2 and CHX groups in staining index at 3 months (1.519 +/- 0.22 versus 1.457 +/- 0.24 SE) and patient subjective evaluation of the mouthwashes. Radiographic bone loss was 0.79 +/- 0.23 and 1 +/- 0.13 SE at 3 months and 1.06 +/- 0.13 and 1.27 +/- 0.25 at 12 months for the CHX and AmF/SnF2 groups, respectively; the difference was statistically insignificant (P = 0.388 and 0.504, respectively). CONCLUSION: Both CHX and AmF/SnF2 mouthwashes can be used post-surgically after one-stage implant surgery.     

Crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged and submerged implants in the canine mandible

BACKGROUND: Today, implants are placed using both non-submerged and submerged approaches, and in 1- and 2-piece configurations. Previous work has demonstrated that peri-implant crestal bone reactions differ radiographically under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of the interface (microgap) between the implant and abutment/restoration in 2-piece configurations. The purpose of this investigation was to examine histometrically crestal bone changes around unloaded non-submerged and submerged 1- and 2-piece titanium implants in a side-by-side comparison. METHODS: A total of 59 titanium implants were randomly placed in edentulous mandibular areas of 5 foxhounds, forming 6 different implant subgroups (types A-F). In general, all implants had a relatively smooth, machined coronal portion as well as a rough, sandblasted and acid-etched (SLA) apical portion. Implant types A-C were placed in a non-submerged approach, while types D-F were inserted in a submerged fashion. Type A and B implants were 1-piece implants with the rough/smooth border (r/s) at the alveolar crest (type A) or 1.0 mm below (type B). Type C implants had an abutment placed at the time of surgery with the interface located at the bone crest level. In the submerged group, types D-F, the interface was located either at the bone crest level (type D), 1 mm above (type E), or 1 mm below (type F). Three months after implant placement, abutment connection was performed in the submerged implant groups. At 6 months, all animals were sacrificed. Non-decalcified histology was analyzed by evaluating peri-implant crestal bone levels. RESULTS: For types A and B, mean crestal bone levels were located adjacent (within 0.20 mm) to the rough/smooth border (r/s). For type C implants, the mean distance (+/- standard deviation) between the interface and the crestal bone level was 1.68 mm (+/- 0.19 mm) with an r/s border to first bone-to-implant contact (fBIC) of 0.39 mm (+/- 0.23 mm); for type D, 1.57 mm (+/- 0.22 mm) with an r/s border to fBIC of 0.28 mm (+/- 0.21 mm); for type E, 2.64 mm (+/- 0.24 mm) with an r/s border to fBIC of 0.06 mm (+/- 0.27 mm); and for type F, 1.25 mm (+/- 0.40 mm) with an r/s border to fBIC of 0.89 mm (+/- 0.41 mm). CONCLUSIONS: The location of a rough/smooth border on the surface of non-submerged 1-piece implants placed at the bone crest level or 1 mm below, respectively, determines the level of the fBIC. In all 2-piece implants, however, the location of the interface (microgap), when located at or below the alveolar crest, determines the amount of crestal bone resorption. If the same interface is located 1 mm coronal to the alveolar crest, the fBIC is located at the r/s border. These findings, as evaluated by non-decalcified histology under unloaded conditions, demonstrate that crestal bone changes occur during the early phase of healing after implant placement. Furthermore, these changes are dependent on the surface characteristics of the implant and the presence/absence as well as the location of an interface (microgap). Crestal bone changes were not dependent on the surgical technique (submerged or non-submerged).     

非埋植型与埋植型牙种植体骨界面改建的X线观察

目的 比较非埋植型与埋植型两种不同种植方式种植体－骨界面组织变化的异同。方法 选用成年杂种犬8只，在其下颌分别植入埋植型与非埋植型种植体，分不同时期处死动物，采用X线对非埋植型与埋植型种植体－骨界面愈合过程进行动态观察，比较两者者界面改建的异同。结果 X线观察1、2、4周非埋植型和埋植型种植体－骨界面新骨形成的速度与骨性结合的程度均无明显差异。12周时，非埋植型和埋植型种植体与骨组织均紧密接触，但非埋植型种植体颈部观察到牙槽骨轻微吸收现象。结论 非埋植型种植体尽管植入后基桩在整个愈合过程中承受了一定的咬合力，但它能与埋植型种植体一样获得良好的骨结合。     

Guided bone regeneration around non-submerged implants in narrow alveolar ridges: a prospective long-term clinical study

OBJECTIVES: This prospective clinical study investigates long-term survival and clinical parameters of non-submerged implants with large buccal dehiscences treated with a deproteinized bovine bone mineral xenograft and a non-resorbable membrane in a one-stage approach. MATERIAL AND METHODS: Sixteen consecutive non-submerged implants (ITI Straumann) were installed in narrow alveolar ridges in 13 patients (age range: 25-61 years). All patients were non-smokers. On the buccal site the bone dehiscence ranged between 3 and 9 mm. Primary stability was achieved in all but one implant. The exposed threads were covered with a xenograft (Bio-Oss) and a non-resorbable expanded polytetrafluoroethylene membrane. The flap was sutured leaving the implant head non-submerged. The membrane was removed when (1) the membrane became exposed or (2) after a maximum of 24 weeks. All implants received singular cemented crowns. The implants were followed for a period ranging from 12 to 114 months. Whole-mouth plaque index (Pl), the % of bleeding on probing (BOP), probing depth and signs of peri-implantitis were recorded. Every year periapical radiographs were taken using a long cone technique. RESULTS: All but one implant integrated successfully. At the time of membrane removal, all previously exposed threads were completely covered with richly vascularized tissue except for two implants where the coverage reached 63% and 87%, respectively. The whole-mouth plaque score and BOP remained low in all patients during the observation period. None of the implants had plaque and, except for one implant BOP never occurred. All implants were stable and in function. Swelling, redness or purulence was never observed. On the periapical radiographs no bone resorption was observed on the mesial and distal site except for one implant in one patient with a mesial and distal bone resorption of 2 and 3 mm. Probing depth was never higher than 3 mm except for one patient where the implant was placed deeply subgingival for esthetical reasons. CONCLUSION: This prospective long-term study shows that with the use of non-submerged transmucosal implants, large bony dehiscences can be treated in a one-stage approach using a stiff non-resorbable membrane combined with a xenograft.     

��ͬ��ֲϵͳ����ʽ�������ʽ��ˮƽ��ֲ����Χ�DZ仯�ıȽϷ���

??Objective    To compare the change of the bone around bone level implants using submerged and non-submerged implants in different implant systems. Methods    Totally 450 implant restorations of 256 patients were chosen from June 2008 to May 2013??in Center of Implant Dentistry??School of Stomatology of China Medical University. The numerical values of bone resorption around the implants were measured after the stage ?? surgery and ?? surgery of dental implantation??the current restoration day and one year after the restorations accomplished on digital panoramic radiographs or small dental films. X-ray films were chosen corresponding to submerged implants because non-submerged implants did not have the stage ?? surgery of dental implantation. Results    During unloaded healing period??from the stage I surgery to the stage ?? surgery??and one year after that??the numerical values of bone resorption around the bone level implants such as Dentium??Bego and 3I between submerged and non-submerged implants had no significant difference??P > 0.05??. The numerical values of bone resorption of three kinds of bone level implants also has no significant difference??P > 0.05??. Conclusion    Submerged or non-submerged implants have no significant effect on the numerical values of bone resorption around implants. Change of the bone around implants in three implant systems has no significant difference. The clinical effects are better.     

The effects of interimplant distances on papilla formation and crestal resorption in implants with a morse cone connection and a platform switch: a histomorphometric study in dogs

BACKGROUND: Implant esthetics have been the focus of attention for the last few years, and one of the most important points is the effect that interimplant distances can have on papilla formation and bone loss. The aim of this study was to evaluate the effect that distances of 1, 2, and 3 mm between implants after prosthetic restoration will have on crestal bone resorption (from the top of the implant to the bone crest [TI-BC]) and bone resorption (from the top of the implant to the first bone-to-implant contact TI-BIC) in two-stage implants used in a submerged and non-submerged protocol. METHODS: The mandibular bilateral premolars of seven dogs were extracted, and after 12 weeks, each dog received eight implants. The implants were placed so that three interimplant contact points were created, with 1-mm (group 1), 2-mm (group 2), and 3-mm (group 3) distances constructed on each side. The sides and the position of the groups were randomly selected. After 12 weeks, the implants received metallic prostheses with 5 mm between the contact point and the bone crest. After 8 weeks more, the animals were sacrificed. RESULTS: The TI-BC was 0.20 and 0.18 mm for group 1, 0.15 and 0.14 mm for group 2, and 0.15 and 0.15 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BC was 0.16 mm for non-submerged and 0.16 mm for submerged implants. The TI-BIC was 0.32 and 0.30 mm for group 1, 0.19 and 0.21 mm for group 2, and 0.30 and 0.24 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BIC was 0.26 mm for non-submerged and 0.25 mm for submerged implants. There was no statistical difference for any of the parameters (analysis of variance [ANOVA]). CONCLUSION: Distances of 1, 2, and 3 mm between implants do not result in statistically significant differences on TI-BC and TI-BIC around submerged or non-submerged implants with a Morse cone connection and a platform switch.     

Effects of Implant Design and Surface on Bone Regeneration and Implant Stability: An Experimental Study in the Dog Mandible

Background: Previous experimental studies have shown a higher degree of bone‐implant contact for surface‐enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit‐blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit‐blasted, partly microthreaded Astra Tech implants and one standard Branemark implant were bilaterally placed in each dog. On one side, 3 ± 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorpho‐metric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well‐integrated implants with varying degrees of bone repair at the defect sites. The greater bone‐implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone—implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.     

Immediately restored, single-tapered implants in the anterior maxilla: prosthodontic and aesthetic outcomes after 1 year

Background: Conventional implant protocols advocate a two-stage technique with a load-free, submerged healing period. Recent studies suggest that immediate restoration of single implants may be a viable treatment option. Purpose: The purpose of this study was to evaluate prosthodontic and aesthetic peri-implant mucosal outcomes of immediately restored, Southern single-tapered implants in the anterior maxilla after 1 year. Materials and Methods: Participants (mean age: 43.25 years; range: 23–71 years) satisfying specified inclusion criteria were randomly allocated to conventional two-stage restoration (control group; n=14) and immediate restoration groups (test group; n =14) in a randomized controlled clinical trial. Tapered, roughened-surface Southern implants were placed using a standardized technique, and implant level bone impressions were made. Provisional screw-retained crowns, out of occlusion, were placed at second-stage surgery after 26 weeks for the conventional restoration group, and within 4 hours of implant placement for the immediate restoration group. Both groups had definitive screw-retained metal-ceramic crowns placed in occlusion 8 weeks later. Peri-implant mucosal response and papilla index were recorded 4 weeks after definitive crown placement to allow for mucosal maturation and at 1 year. Prosthodontic and aesthetic outcomes were assessed using established criteria. Results: There were no significant differences within, or between, the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length. There were no significant differences in the implant success rate as determined by radiographic bone loss and stability tests after 1 year. There were no significant differences in prosthodontic maintenance, peri-implant mucosal response, and papilla index between the two groups over 1 year. Conclusions: Tapered, roughened-surface implants immediately restored with single provisional crowns at surgery and definitive crowns 8 weeks later were as prosthodontically and aesthetically successful as conventionally restored two-stage implants during the first year of service. Restoring single implants immediately with screw-retained crowns is an efficient procedure, but the short-term outcome is by no means superior to a conventional two-stage approach.     

不同种植系统埋置式与非埋置式骨水平种植体周围骨变化的比较分析

目的    比较分析不同种植系统埋置式与非埋置式骨水平种植体周围的骨组织变化。方法    选择2008年6月至2013年5月于中国医科大学附属口腔医院种植中心接受种植修复的患者256例,总计450枚种植体。测量种植Ⅰ期、种植Ⅱ期、修复后当天及修复后1年4个时间点的数字化曲面断层片或根尖X线片,因非埋置式无二期手术,故选择与之相对应时间点的X线片,测量种植体周围骨吸收量。结果    在非负荷愈合期（从种植Ⅰ期到种植Ⅱ期）及负荷1年（从修复后当天到修复后1年）两个时间段,埋置式与非埋置式愈合对Dentium、Bego及3I三种骨水平种植体周围牙槽骨吸收量的影响,差异无统计学意义（P > 0.05）;3种种植系统的种植体周围骨组织吸收量比较,差异无统计学意义（P > 0.05）。结论    采用埋置式或非埋置式种植对种植体周围骨组织吸收量没有明显影响;3种种植系统的种植体周围骨变化无明显差异,临床效果均较好。     

A preliminary report of patients treated with early loaded implants using computerized tomography-guided surgical stents: flapless versus conventional flapped surgery

The objective of this clinical study was to compare the survival rates of early loaded implants placed using flapless and flapped surgical techniques and to determine the bone density in the implant recipient sites using computerized tomography (CT). The study population consisted of 12 patients who were referred implant placement. One group consisted of five patients referred for the placement of 14 implants and treated with a flapless procedure. The other group consisted of seven patients referred for the placement of 45 implants with a conventional flapped procedure. Patients were selected randomly. CT machine was used for pre-operative evaluation of the jaw bone and the mean bone density value of each implant recipient site was recorded in Hounsfield units (HU). All implants were placed using CT-guided surgical stents. The early loading protocols included 2 months of healing in the mandible and 3 months of healing in the maxilla. Single-implant crowns, implant-supported fixed partial dentures, and implant-retained over dentures were delivered to the patients. Of 59 implants placed, one was lost in the conventional flapped group within the first month of healing, meaning overall implant survival rate of 98.3% average 9 months later. The highest average bone density value (801 +/- 239 HU) was found in the anterior mandible, followed by 673 +/- 449 HU for the posterior maxilla, 669 +/-346 HU for the anterior maxilla and 538 +/- 271 HU for the posterior mandible. The results of this study show that the early loading of implants placed utilizing flapless surgical technique with CT-guided surgical stents may be possible.