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Literature Update Sep-Oct 2010

Acta Odontologica Scandinavica

Vol. 68 No. 5 (September 2010)

Zhu Y, Xiao L, Shen D, Hao Y.  Competition between yogurt probiotics and periodontal pathogens in vitro.

Acta Odontol Scand 2010;68(5):261-268.

Four probiotic bacterial species (L bulgaricus, S thermophilus, L acidophilus and Bifidobacterium) were isolated from yogurt to assess the antimicrobial activity versus various periodontal pathogens. All periodontal pathogens were inhibited by fresh yogurt but antimicrobial activity was lower with heat-treated yogurt. However, neither yogurt inhibited the ‘protective’ bacteria S sanguinis. Competition between the bacteria depended  on  the  sequence  of  inoculation,  and  antimicrobial properties were reduced if both probiotic bacteria and periodontal pathogens were inoculated simultaneously. Probiotic yogurt and its bacteria can therefore inhibit certain periodontal pathogens but do not affect periodontal protective bacteria.

 

Clinical Implant Dentistry and Related Research

Vol. 12 No. 3 (September 2010)

Safii SH, Palmer RM, Wilson RF.  Risk of implant failure and marginal bone loss in subjects with a history of

periodontitis: a systematic review and meta-analysis. Clin Implant Dent Relat Res 2010;12(3):165-174.

A literature search was conducted for clinical studies comparing periodontal/peri-implant variables between healthy subjects and those with periodontitis. A total of 17 potential studies were identified, of which six compared implant treatment in periodontally compromised and periodontally healthy subjects. Meta-analysis of implant survival was possible for five studies and meta-analysis of peri-implant bone loss was possible for four studies. Periodontally healthy patients showed a significantly greater odds ratio for implant survival, while marginal bone loss was significantly greater in subjects with periodontitis. The risk of implant failure and marginal bone loss is therefore greater in patients with periodontitis.

 

Shabestari GO, Shayesteh YS, Khojasteh A, Alikhasi M, Moslemi N, Aminian A, Mazaeli R, Eslami B, Treister NS.  Implant placement in patients with oral bisphosphonate therapy: a case series. Clin Implant Dent Relat Res 2010;12(3):175-180.

A  total of  21 patients with osteoporosis and who  were receiving bisphosphonate therapy received 46

implants, which were evaluated for probing depth, mobility, thread exposure and bleeding on probing. No signs of peri-implantitis were observed in any of the patients. Time of bisphosphonate therapy relative to implant placement, implant location, type of prosthesis and opposing dentition had no significant influence. Bisphosphonate therapy before or after implant placement therefore did not jeopardize osseointegration or clinical or radiographic outcomes.

 

Tözüm TF, Turkyilmaz I, Bal BT.  Initial stability of two dental implant systems: influence of buccolingual width and   probe   orientation   on   resonance   frequency   measurements.   Clin   Implant   Dent   Relat   Res

2010;12(3):194-201.

Implants from two dental implant systems (diameters 3.75 mm and 4.2 mm) were placed in acrylic models and buccolingual thinning of the models was performed in 2 mm increments from 0 to 8 mm. resonance frequency analysis were then performed. Implant stability quotient 8ISQ) significantly decreased for both implant systems and diameters for all time points of the acrylic block. Significantly higher ISQ values were observed for the implant system with more threads. However, ISQ measurement was affected by the orientation of the probe.

 

Kleis WK, Kämmerer PW, Hartmann S, Al-Nawas B, Wagner W.  A comparison of three different attachment systems  for  mandibular  two-implant  overdentures:  one-year  report.     Clin  Implant  Dent  Relat  Res

2010;12(3):209-218.

Each of 60 patients with an edentulous mandible received two implants in the interforaminal region. After 3.5 months of healing, overdentures were placed using one of three different attachment systems (Locator attachment or one of two types of ball attachment [TG-O-Ring or Dal-Ro]). Prosthodontic maintenance, biological complications, patient experience and oral health-related quality of life were evaluated after 12 months. Eight of the 120 implants were lost after 1 year, giving an implant survival rate of 90.4%. A total of

34 complications occurred with the Locator system, 14 with the TG-O-Ring system and seven with the Dal- Ro system. No differences in biological complications or oral health-related quality of life were observed.


 

Clinical Oral Implants Research

Vol. 21 No. 9 (September 2010)

Caneva M, Salata LA, De Souza SS, Bressan E, Botticelli D, Lang NP.  Hard tissue formation adjacent to implants of various size and configuration immediately placed into extraction sockets: an experimental study

in dogs. Clin Oral Implants Res 2010;21(9):885-890.

Cylindrical (3.3 mm diameter; control) or conical (5.0 mm diameter; test) implants were placed in extraction sockets in dog mandibles and bone resorption was evaluated after 4 months. Alveolar crest resorption was observed with both implant types and was more pronounced at the buccal aspect, but was significantly greater with the test implants. The control implants were associated with deeper lingual defects. Root formed wide implants therefore do not inhibit alveolar resorption.

 

Matarasso S, Rasperini G, Iorio Siciliano V, Salvi GE, Lang NP, Aglietta M.  A 10-year retrospective analysis of radiographic bone-level changes of implants supporting single-unit crowns in periodontally compromised vs. periodontally healthy patients. Clin Oral Implants Res 2010;21(9):898-903.

Mean bone loss around two different types of implants placed in 20 periodontally healthy or periodontally compromised patients was retrospectively evaluated after 10 years. Implant survival ranged from 85-95% between the four groups, but the differences were not statistically significant. Mean bone loss and the number of sites with bone loss ≥ 3 mm were significantly greater in the periodontally compromised patients, regardless of the implant system used.

 

Schwarz F, Ferrari D, Balic E, Buser D, Becker J, Sager M.  Lateral ridge augmentation using equine- and bovine-derived cancellous bone blocks: a feasibility study in dogs. Clin Oral Implants Res 2010;21(9):904-

912.

Box defects were created in the alveolar ridges of dog mandibles and treated with either equine- or bovine- derived cancellous bone block covered with a collagen membrane. After 12 weeks, bovine bone blocks were found to be embedded in fibrous connective tissue, with no signs of biodegradation. However, significantly increased cell-mediated degradation was found with the equine bone blocks, Bone ingrowth was also higher with the equine bone blocks, but the difference was not significant. Equine bone blocks did not appear to be associated with improved bone formation.

 

Merheb J, Coucke W, Jacobs R, Naert I, Quirynen M.  Influence of bone defects on implant stability. Clin

Oral Implants Res 2010;21(9):919-923.

A total of 32 implants were placed in human cadaver jaws according to four types of bone defect: marginal bone  loss,  peri-apical  bone  defect,  constant  width  dehiscence  or  constant  length  dehiscence.  Implant stability was measured using the Periotest and Osstell devices before and during bone removal. Significant differences in implant stability were noted from baseline after removal of 2 mm marginal bone, 5 mm (Osstell) or 8 mm (Periotest) of peri-apical bone, removal of up to 180° of the implant perimeter for a 6 mm long dehiscence, and after removal of 10 mm (Osstell) or 6 mm (Periotest) for a 3 mm wide dehiscence. The implant stability measurements therefore did not appear to be very sensitive regarding the detection of peri- implant bone loss.

 

Lindgren C, Hallman M, Sennerby L, Sammons R.  Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate. Clin Oral Implants Res 2010;21(9):924-930.

Bilateral maxillary sinus floor augmentation was performed in 11 patients using deproteinized bovine bone (DBB; Bio-Oss) in one side and biphasic calcium phosphate (BCO; Straumann BoneCeramic) in the contralateral side. Micro-implants were placed and removed after 8 months with the surrounding bone core. Both types of graft material were in direct contact with or surrounded by newly formed bone. Mean Ca/P ratios were 1.61 and 1.62 for DBB and DBB-augmented bone, respectively, and 1.5 and 1.52 for BCP and BCP-augmented bone, respectively, consistent with the dissolution and gradual substitution of the β-TCP part of BCP over the healing period.


 

Rossi F, Ricci E, Marchetti C, Lang NP, Botticelli D.  Early loading of single crowns supported by 6-mm-long implants with a moderately rough surface: a prospective 2-year follow-up cohort study. Clin Oral Implants Res 2010;21(9):937-943.

A total of 40 implants (6 mm long and either 4.1 mm or 4.8 mm wide) were placed in 35 patients, and implant

survival, marginal bone loss and resonance frequency analysis (RFA) measurements were performed. The implant survival rate was 95% (two implants lost) after 2 years, and mean marginal bone loss was 0.34 ±

0.38 mm before loading and 0.23 ± 0.33 mm and 0.21 ± 0.39 mm at 1 and 2 years, respectively. Implant stability increased from implant placement to 6 weeks and the crown/implant ratio decreased from 1.5 at prosthesis  placement  to  1.8  at  2 years. High implant survival and moderate bone loss was therefore observed  after  2  years,  but  longer-term  investigations  are  necessary  to  assess  the  reliability  of  short implants.

 

Mordenfeld A, Hallman M, Johansson CB, Albrektsson T.  Histological and histomorphometrical analyses of biopsies harvested 11 years after maxillary sinus floor augmentation with deproteinized bovine and autogenous bone. Clin Oral Implants Res 2010;21(9):961-970.

Thirty maxillary sinuses in 20 patients were augmented with 80% deproteinized bovine bone and 20% autogenous bone. Biopsies were taken from 11 patients after 11 years and evaluated. Mean 44.7 ± 16.9%, lamellar bone, 38 ± 16.9% marrow space and 17.3 ± 13.2% deproteinized bovine bone were observed in the biopsies, with 61.5 ± 34% bovine bone to bone contact. Length and area of the particles did not differ significantly between 11 years and 6 months in the same patients.

 

Korfage A, Scheon PJ, Raghoebar GM, Roodenburg JLN, Vissink A, Reintsema H. Benefits of dental implants installed during ablative tumour surgery in oral cancer patients: a prospective 5-year clinical trial. Clin Oral Implants Res 2010;21(9):971-979.

Questionnaires and clinical assessments were administered to 50 edentulous oral cancer patients in whom prosthetic problems were expected, and implants were placed during tumor ablative surgery in the interforaminal area. After 5 years, 26 patients had died and a further four were excluded from the analysis. The prosthesis remained in function in the remaining 20 patients. The implant survival rate in these patients was 89.4% (13 implants lost) in irradiated bone and 98.6% (one implant lost) in non-irradiated bone. Peri- implant tissues were healthy and patients were satisfied with their prostheses. Implant placement during tumor ablative surgery can therefore benefit oral cancer patients.

 

Clinical Oral Investigations

Vol. 14 No. 4 (August 2010)

Eraslan O, İnan Ö.  The effect of thread design on stress distribution in a solid screw implant: a 3D finite

element analysis. Clin Oral Investig 2010;14(4):411-416.

Three-dimensional finite element models were created for four different thread forms (V-thread, buttress, reverse buttress and square) for solid screw implants and 100 N static axial occlusal loading was applied to evaluate the stress distributions. Maximum stresses were found to be at the loading areas of abutments and cervical cortical bone regions for all configurations. Stresses at cortical bone were higher than those for spongious bone, and the concentrations at the first thread were higher than for other threads. Stress distribution patterns were similar for all configurations but the concentration of compressive stresses was different.

 

Danza M, Tortora P, Quaranta A, Perrotti V, Vozza I, Piattelli A.  Randomised study for the 1-year crestal bone maintenance around modified diameter implants with different loading protocols: a radiographic evaluation. Clin Oral Investig 2010;14(4):417-426.

In 25 patients, 40 implants were placed and loaded either immediately (20 implants) or conventionally (20 implants). Bone level measurements were evaluated. No significant differences in bone loss between conventionally or immediately loaded implants were noted in the maxilla, but slight differences were noted in the mandible, where lower marginal bone loss was observed.

 

 

Harder S, Dimaczek B, Açil Y, Terheyden H, Freitag-Wolf S, Kern M.  Molecular leakage at implant-abutment connection in vitro investigation of tightness of internal conical implant-abutment connection against endotoxin penetration. Clin Oral Investig 2010;14(4):427-432.

The inner parts of two different internal conical connection implants (Astra Tech and Ankylos; eight implants per system) were inoculated with endotoxin and abutments were screwed in place. The implants were then stored in pyogen-free water for 168 h, with samples taken after 5 min, and 24, 72 and 168 h to evaluate endotoxin contamination. Contamination was observed after varying storage times, and implants in the Ankylos group exhibited contamination after only 5 min. Only one implant (in the Astra Tech group) showed no signs of contamination after 168 h. The internal conical connections tested therefore did not prevent endotoxin leakage.

 

European Journal of Oral Implantology

Vol. 3 No. 3 (September 2010)

Esposito M, Grusovin MG, Polyzos IP, Felice P, Worthington HV.  Timing of implant placement after tooth

extraction: immediate, immediate-delayed or delayed implants? A Cochrane systematic review. Eur J Oral

Implantol 2010;3(3):189-205.

A systematic literature review was performed according to Cochrane criteria for randomized controlled trials of various implant placement protocols with at least 1 year follow-up data and with outcomes including implant  and  prosthesis  failures,  complications,  patient  satisfaction,  esthetics  and  marginal  bone  level changes. The search identified 14 trials, of which seven were included. Two studies comparing immediate versus delayed implants found no significant differences between the groups. In one trial comparing immediate-delayed versus delayed implants, perceived time to functional loading, patient satisfaction and judgment of the peri-implant mucosa was better with immediate-delayed implants after 2 years, but there were no differences after 5 years. No significant differences between immediate and immediate-delayed implants were observed in one trial, and no significant differences were observed in three trials evaluating different bone grafting techniques. Evidence to determine the advantages of any implant placement protocol is therefore insufficient.

 

Capelli M, Esposito M, Zuffetti F, Galli F, Del Fabbro M, Testori T. A 5-year report from a muticentre randomised  clinical  trial:  immediate  non-occlusal  versus  early  loading  of  dental  implants  in  partially edentulous patients. Eur J Oral Implantol 2010;3(3):209-219.

Implants were placed in 52 patients and loaded either immediately (temporary restoration out of occlusion within 24 h; 52 implants in 25 patients) or early (restoration placed after 2 months; 52 implants in 27 patients). One patient in the early loading group dropped out before the 1-year follow-up and one implant in the immediate loading group failed. Peri-implant bone loss and soft tissue changes were observed in both groups, but the differences between the groups were not significant. Significant recession of the vestibular soft tissues was observed after 5 years for immediate implants only.

 

Checchi  L,  Felice  P,  Antonini  ES,  Cosci  F,  Pellegrino  G,  Esposito  M.  Crestal  sinus  lift  for  implant rehabilitation: a randomised clinical trial comparing the Cosci and Summers techniques. A preliminary report on complications and patient preference. Eur J Oral Implantol 2010;3(3):221-232.

In 15 patients, crestal sinus lift was performed using the Cosci or Summers techniques with bone substitutes and 19 dental implants were placed for each technique and left to heal submerged. The implants were provisionally loaded after 6 months and definitive metal-ceramic restorations were placed after a further 4 months. There were no implant failures in either group. Discomfort was reported in 12 patients with the Summers technique, with one case of sinus membrane perforation, but no discomfort or complications were reported with the Cosci technique. Implant placement time was also significantly lower with the Cosci technique  (24  versus  33  min).  The  Cosci  technique  was preferred by  14/15 patients and by the two operators.

 

Badr  M,  Coulthard  P,  Alissa  A,  Oliver  R.   The  efficacy  of  platelet-rich  plasma  in  grafted  maxillae.  A

randomised clinical trial. Eur J Oral Implantol 2010;3(3):233-234.

Onlay grafting in the maxilla was performed in 22 patients, of whom 16 also received sinus grafting with particulate bone. PRP was mixed with the bone grafts in 13 patients; nine patients received no PRP (control). There was one graft failure in the PRP group, requiring re-grafting. All implants were integrated, and soft tissue healing and graft resorption were not significantly different between the groups. Implant stability was similar at implant placement and exposure between the groups but was significantly higher for posterior implants in the PRP group versus anterior implants at implant placement, but this had no clinical significance. PRP therefore had no appreciable effect.


European Journal of Oral Sciences

Vol. 118 No. 5 (October 2010)

Schley J-S, Heussen N, Reich S, Fischer J, Haselhuhn K, Wolfart S.  Survival probability of zirconia-based

fixed dental prostheses up to 5 yr: a systematic review of the literature. Eur J Oral Sci 2010;118(5):443-450. A literature search was conducted by three reviewers to identify clinical studies with 5-year survival rates up of zirconia-based fixed dental prostheses. From an initial total of 399 articles, 18 were selected for full review, of which nine met the inclusion criteria. The articles included 310 three- to four-unit FDPs and 20

FDPs with > four units. Of these, 19 FDPs failed, giving a 5-year cumulative survival rate of 94.29%, while the 5-year complication-free rates were 76.41% and 91.72% for technical and biological complications, respectively. Chipping was the most frequent technical complication. Survival rates were therefore promising but improvements of the veneering systems are necessary.

 

Implant Dentistry

Vol. 19 No. 4 (August 2010)

Chan H-L, Misch K, Wang H-L.  Dental imaging in implant treatment planning. Implant Dent 2010;29(4):288-

298.

Literature on the use of imaging in dental implant treatment planning was searched, specifically focusing on medical CT and cone-beam CT (CBCT). Medical CT imaging was introduced for implant planning approximately 20 years ago, and can produce accurate, high-resolution 3D images. CBCT has advantages due to its specific design for the oral-maxillofacial region, lower radiation, lower costs and image quality. Such 3D images may help the clinician to select appropriate implant dimensions and predict treatment outcomes.

 

Casado PL, Duarte MEL, Carvalho W, Esmeraldo da Silva L, Barboza EP. Ridge bone maintenance in human after extraction. Implant Dent 2010;29(4):314-322.

A total of 46 alveolar defects were filled with bovine BMP + bovine organic matrix (bOM), BMP + bOM +

absorbable membrane (AM), AM alone, or were left unfilled. Ridge width was evaluated before treatment and after 4 months. All three test groups showed relevant ridge width augmentation, compared to no significant augmentation in the control group. Active bone formation with osteoid, osteoblasts and cell differentiation was observed in the test groups. BMP + bOM can therefore results in viable ridge formation, with or without absorbable membrane.

 

Turkyilmaz I.  One-year clinical outcome of dental implants placed in patients with type 2 diabetes mellitus: a case series. Implant Dent 2010;29(4):323-329.

A total of 23 implants were placed in 10 patients with well-controlled or moderately well-controlled diabetes.

No implant failures occurred up to 1 year, and the mean marginal bone loss was 0.3 ± 0.2 mm. No radiolucency, bleeding on probing or pathologic probing depth was observed. The results indicated that dental implants may be successfully used in patients with well- or moderately well-controlled diabetes, with no significant complications.

 

Rabelo GD, de Paula PM, Rocha FS, Jordão Silva C, Zanetta-Barbosa D. Retrospective study of bone grafting procedures before implant placement. Implant Dent 2010;29(4):342-350.

A total of 136 autogenous bone grafting procedures performed in 93 patients over a 7-year period were

retrospectively evaluated. The most frequently used donor areas were the mandibular external oblique line and ascending ramus (59.64%), while block graft was the most frequently used graft type (67.64%). The majority of procedures (75%) were in the maxilla, with fewer complications than those in the mandible; the most common complication was sinus mucosa perforation in the maxilla and graft exposure in the mandible. Alveolar reconstruction with autogenous bone with subsequent implant placement was found to be a reliable treatment option, but morbidity and complications were frequently observed.

 


 

Manso M, Wassal T. A_10-year longitudinal study of 160 implants simultaneously installed in severely atrophic posterior maxillas grafted with autogenous bone and a synthetic bioactive resorbable graft. Implant Dent 2010;29(4):351-360.

A total of 45 patients received sinus augmentation (in 57 sinuses with 4 mm of residual sub-sinus bone)

with  simultaneous  placement  of  160  implants  in  a  modified  technical  and  biomaterial  protocol  using composite autogenous bone with synthetic bioactive resorbable graft. The mean follow-up time was 61.7 months, and specific cases were followed up with CT scans. Implant survival and success rates were

98.05% and 94.85%, respectively, indicating that the protocol may be a suitable approach for advanced posterior maxillary resorption.

 

International Journal of Oral and Maxillofacial Implants

Vol. 25 No. 4 (July/August 2010)

Yang G-L, He F-M, Song E, Hu J-A, Wang X-X, Zhao S-F.  In vivo comparison of bone formation on titanium implant surfaces coated with biomimetically deposited calcium phosphate or electrochemically deposited

hydroxyapatite. Int J Oral Maxillofac Implants 2010;25(4):669-680.

Implants coated with biomimetically deposited calcium phosphate (BDCaP) or electrochemically deposited hydroxyapatite (EDHA), or uncoated, were randomly placed in rabbit tibiae and evaluated after 2, 4 and 8 weeks. Analysis showed that the BDCaP coating comprised HA and octacalcium phosphate, whereas the EDHA coating comprised only HA. New bone on the EDHA-coated implants was mature after 4 weeks, whereas bone on the BDCaP-coated and control implants was mature after 8 weeks. BIC and bone area were also significantly greater for the EDHA-coated implants at 4 and 8 weeks. The EDHA coating therefore demonstrated good bone formation properties.

 

Choi K-S, Lozada JL, Kan JY, Lee S-H, Kim C-S, Kwon T-G. Study of an experimental microthreaded scalloped implant design: proximal bone healing at different interimplant distances in a canine model. Int J Oral Maxillofac Implants 2010;25(4):681-689.

A total of 70 implants with a microthreaded scalloped design (35 implants) or a flat-top design (35 implants)

were placed in the mandibles of 10 dogs; in five dogs, four of each implant type were placed with an inter- implant distance of 2 mm and three implants of each type in the other five dogs were placed with an inter- implant distance of 5 mm. After 4 months, radiographic and histological analysis showed significantly less bone loss around the scalloped implants than the flat-top implants. No differences were observed between the implants placed at inter-implant distances of 2 or 5 mm for either implant type. The microthreaded scalloped implants were therefore more effective at preserving proximal bone.

 

Gallego L, Junquera L, Meana Á, García E, García V. Three-dimensional culture of mandibular human osteoblasts on a novel albumin scaffold: growth, proliferation, and differentiation potential in vitro. Int J Oral Maxillofac Implants 2010;25(4):699-705.

Osteoblast cells obtained from mandibular bone were cultured in a protein scaffold prepared with plasmatic

albumin and glutaraldehyde-type agent (test) or mineralized cancellous allograft (control). After 90 days, alkaline phosphatase was expressed by cells in the albumin scaffold. Bone-like extracellular matrix was observed in the study scaffold and mineralization of osteoblasts was seen in the albumin scaffold. Osteoblast proliferation in the albumin scaffold was therefore confirmed.

 

Urdaneta RA, Rodriguez S, McNeil C, Weed M, Chuang S-K.  The effect of increased crown-to-implant ratio on single-tooth locking-taper implants. Int J Oral Maxillofac Implants 2010;25(4):729-743.

A  cohort  of  81  patients  who  received  326  single-tooth  implants  and  cementless  restorations  were

retrospectively evaluated. The mean follow-up time was 70.7 months and the mean change in mesiodistal bone level was -0.33 mm. The mean crown-to-implant ratio (C/IR) was 1.6, and C/IR 2.0 was observed in

16% of restorations; these were more likely to have increased crown width, larger implant diameter, larger mesial/distal distance to adjacent structures and deeper sulcular probing. Loosening of maxillary anterior abutment crowns was significantly influenced by increased C/IR, but the risk of crestal bone loss was not increased by a C/IR up to 4.95.

 

 

Lee FK, Tan KB, Nicholls JI.  Critical bending moment of four implant-abutment interface designs. Int J Oral

Maxillofac Implants 2010;25(4):744-751.

Critical bending moment was measured in vitro for four implant-abutment types (Bränemark/CeraOne, Nobel Replace/Easy, Biomet 3i/STA and Lifecore/COC) at 80%, 100% and 120% of the manufacturers’ recommended torque levels. Loads were applied and microstrains were measured while know loads were applied. Mean crestal bending moment at 100% of the recommended torque was 102.21 Ncm, 109.92 Ncm,

83.14 Ncm and 76.79 Ncm for Bränemark-CeraOne, Nobel Replace/Easy, Biomet 3i7STA and Lifecore/COC assemblies, respectively; significant differences between groups and torque levels were noted. Compressive preload by the abutment screw appears to play a key role in maintaining screw joint integrity.

 

Chua J-Y, Takano-Yamamoto T, Hwang C-J.  Effect of miniscrew taper morphology on insertion and removal torque in dogs. Int J Oral Maxillofac Implants 2010;25(4):777-783.

In six dogs, 48 miniscrews were placed with maximum insertion torque, with removal torque assessed after 3

and 12 weeks. A further 48 implants were inserted in almost the same places as those removed, and insertion torque and 3- and 12-week removal torque were recorded once more. Histological analysis was also performed. Mean maximum insertion torque was significantly greater with tapered miniscrews than cylindrical miniscrews, and mean maximum removal torque was significantly greater at 3 weeks but not at 12 weeks. BIC was similar between the groups at 3 weeks, and bone volume/total volume was significantly greater for the tapered miniscrews at 3 weeks. The tapered design therefore increased initial stability but did not influence secondary stability.

 

Liao K-Y, Kan JY, Rungcharassaeng K, Lozada JL, Herford AS, Goodacre CJ. Immediate loading of two freestanding implants retaining a mandibular overdenture: 1-year pilot prospective study. Int J Oral Maxillofac Implants 2010;25(4):784-790.

Ten patients each received two freestanding implants to support a mandibular removable overdenture.

Implant success and marginal bone levels were recorded after 1 year. Two patients, one with one implant failure, dropped out of the study. The mean marginal bone loss was 1.12 ± 1.10 mm and the cumulative implant success rate was 94%. However, if bone loss above the smooth-rough implant surface was considered, the mean bone loss was 0.73 mm. Osseointegration was confirmed by Periotest, and no irreversible prosthetic or surgical complications were noted. Two immediately loaded unsplinted implants retaining a mandibular overdenture was therefore a suitable treatment approach.

 

Brennan M, Houston F, O’Sullivan M, O’Connell B.  Patient satisfaction and oral health-related quality of life outcomes  of  implant  overdentures  and  fixed  complete  dentures.  Int  J  Oral  Maxillofac  Implants

2010;25(4):791-800.

A population of 62 patients who had received implant-supported overdentures or complete implant fixed prostheses were identified to assess oral health-related quality of life (via the Oral Health Impact Profile-14 tool) and patient satisfaction (via a survey). Patient satisfaction was high in both prosthetic groups, but satisfaction with cost, treating doctor and the ability to perform oral hygiene were lower in the fixed prosthesis group, and satisfaction with chewing capacity, with esthetics, and overall, was significantly lower in the overdenture group. Oral health-related quality of life was high, but psychological discomfort and disability were significantly lower in the fixed prosthesis group. Patients with an overdenture were therefore generally less satisfied and had lower oral health-related quality of life than those with a fixed prosthesis.

 

Merli M, Lombardini F, Esposito M.  Vertical ridge augmentation with autogenous bone grafts 3 years after loading: resorbable barriers versus titanium-reinforced barriers. A randomized controlled clinical trial. Int J Oral Maxillofac Implants 2010;25(4):801-807.

Vertical bone augmentation was performed with autogenous bone grafts in 22 patients; half of the patients

received a resorbable collagen barrier supported by an osteosynthesis plate, while half received a non- resorbable ePTFE barrier. Follow-up times ranged from provisional loading to 3 years post-loading. There were no prosthetic or implant failures. Peri-implant bone loss was significant, but there was no significant difference in bone loss between the groups at 1 and 3 years (mean bone loss 0.55 mm and 0.53 mm for resorbable and non-resorbable barriers, respectively, at 3 years).

 


 

International Journal of Periodontics and Restorative Dentistry

Vol. 30 No. 4 (July/August)

Su H, González-Martin O, Weisgold A, Lee E. Considerations of implant abutment and crown contour: critical

contour and subcritical contour. Int J Periodontics Restorative Dent 2010;30(4):335-343.

The implant abutment can be used to effect the transition from the circumferential design of the implant head to the design of the tooth anatomy. Overcontouring of the abutment can cause apical positioning of the gingival margin and undercontouring has the opposite effect, but the concept of ‘contouring’ as it applies to implant dentistry should be re-defined. Two zones in the abutment and crown the critical and subcritical contour, can modify the soft tissue profile. The effect of modifications at these zones was therefore investigated.

 

Blus  C,  Szmukler-Moncler  S.   Atraumatic  tooth  extraction  and  immediate  implant  placement  with piezosurgery: evaluation of 40 sites after at least 1 year of loading. Int J Periodontics Restorative Dent

2010;30(4):355-363.

A total of 40 teeth were extracted in 23 patients and immediately replaced with implants. The fibers of the periodontal  ligament  were  cut  using  piezosurgery  and  the  teeth/roots  mobilized  and  removed  without fracture. Notching of the apical third of the palatal wall was made during implant placement, or interradicular bridge was performed with no complications. All implants were osseointegrated and successful for up to 12 months. Extraction by piezosurgery can therefore be atraumatic, with predictable subsequent implant placement.

 

McAllister BS, Haghighat K, Prasad HS, Rohrer MD.  Histologic evaluation of recombinant human platelet- derived  growth  factor-BB  after  use  in  extraction  socket  defects:  a  case  series.  Int  J  Periodontics Restorative Dent 2010;30(4):365-373.

Twelve extraction sockets were treated with either β-tricalcium phosphate or anorganic deproteinized bovine

bone, both with 0.3 mg/mL rhPDGF-BB. Histologic evaluation after 3 months of uneventful socket healing showed similar results in both groups (21% and 24% vital bone in the β-TCP and bovine bone groups, respectively).  Implants  were  placed  without  the  need  for  further  grafting,  and  the  subsequent  implant success rate was 100%.

 

Kim Y-K, Kim S-G, Yun P-Y, Hwang J-W, Son M-S.  Prognosis of single molar implants: a retrospective study. Int J Periodontics Restorative Dent 2010;30(4):401-407.

A total of 96 single implants were placed in molar sites in 87 patients. Primary implant failure and delayed

implant failure occurred for two and four implants, respectively, all of which were in second molar sites. The cumulative implant survival rate was therefore 91.1% and mean crestal bone loss after 3 years was 0.2 mm. There was a significant correlation between prosthetic complications and mesiodistal cantilever. The risks of failure and prosthetic complications in single molar sites were therefore high.

 

International Journal of Prosthodontics

Vol. 23 No. 4 (July/August 2010)

Nakamura  K,  Kanno  T,  Milleding  P,  Örtengren  U.   Zirconia  as  a  dental  implant  abutment  material:  a

systematic review. Int J Prosthodont 2010;23(4):299-309.

A literature search was performed for studies with zirconia dental implant abutments. From an initial 380 articles, 11 studies on mechanical properties, four on peri-implant soft tissue around zirconia abutments, seven on plaque accumulation on zirconia and three clinical studies on abutment survival fulfilled the inclusion criteria. Zirconia abutments appeared to be reliable in the anterior region in terms of biology and mechanics, and may have less plaque retention than titanium. Implant function without fracture or peri- implant lesions was demonstrated in three follow-up studies.

 

 

Cune M, Burgers M, van Kampen F, de Putter C, van der Bilt A.  Mandibular overdentures retained by two implants: 10-year results from a crossover clinical trial comparing ball-socket and bar-clip attachments. Int J Prosthodont 2010;23(4):310-317.

A total of 18 patients with mandibular dentures received two implants to support overdentures with magnet,

ball-socket or bar-clip attachments; the attachment of each patient’s choosing was fitted to the overdenture at the end of the study. After 10 years, 14 patients were available for analysis (seven each with ball-socket and bar-clip attachments). Periodontal parameters were evaluated and overall satisfaction was assessed using a visual analog scale at baseline and after 10 years. Appreciation of the overdentures was initially high and was maintained over time. Satisfaction ratings were not significantly different between patients with the two attachment types, and healthy peri-implant mucosa and stable marginal bone levels were noted.

 

Ma  S,  Tawse-Smith  A,  Thomson  WM,  Payne  AGT.   Marginal  bone  loss  with  mandibular  two-implant