Do block graft complications lead to treatment failure?


Implant supported restorations were placed in 137 atrophic ridges that were augmented with cancellous block-bone allografts. Recipient site complications associated with block grafting were recorded.


Total block-graft failure occurred in 7% of cases and partial block graft failure occurred in 8% of cases. The implant failure rate was 4.4%. Soft tissue complications included membrane exposure (42 of 137), incision line opening (41 of 137), and perforation of the mucosa of the grafted bone (19 of 137). A higher rate of complications was noted in the mandible.


Soft tissue complications did not necessarily result in total loss of cancellous block allograft. Total bone-block failure (8% of cases) and implant failure (4.4% of cases) were uncommon with block grafting although approximately 30% of patients experienced adverse events.

for more information please refer to :

J Periodontol. 2010 Dec;81(12):1759-64

Analysis of complications following augmentation with cancellous block allografts.

Chaushu G1, Mardinger O, Peleg M, Ghelfan O, Nissan J.

Does Timing of Restoration Affect Implant Marginal Bone Loss?





A meta-analysis was performed on eleven studies that compared marginal bone loss between implants restored with the following protocols: Immediate restoration/loading; early loading; conventional loading 




 After adjusting for implant placement levels, no significant difference was found when comparing marginal bone loss for four scenarios: 

  1. immediate restoration/loading + delayed placement versus conventional loading + delayed placement.
  2. immediate restoration + delayed placement versus early loading + delayed placement.  
  3. early loading + delayed placement versus conventional loading + delayed placement.
  4. immediate loading + immediate placement versus conventional loading + immediate placement.


The timing of restoration does not have an effect on implant marginal bone loss according to this meta-analysis when comparing the clinical scenarios outlined above.




Effect of the timing of restoration on implant marginal bone loss: a systematic review.


Suarez F, Chan HL, Monje A, Galindo-Moreno P, Wang HL.


J Periodontol. 2013 Feb;84(2):159-69.


Does Sinus Membrane Perforation Affect Implant Survival?


Retrospective data was obtained from 23 patients who had undergone sinus augmentation procedures with a total of 40 treated sinuses.  Sinuses were grafted with mineralized cancellous bone allograft, anorganic bovine bone matrix, or biphasic calcium phosphate.  There were 15 perforated sinuses which were repaired with an absorbable collagen membrane.  Histologic cores were taken from all treated sinuses 26 to 32 weeks after surgery.  


Average percentage of vital bone was 26.3% ± 6.3% in the repaired sinuses versus 19.1% ± 6.3% in the non-perforated sinuses.  The implant success rate was 100% in the repaired sinuses versus 95.5% in the non-perforated sinuses.  There was no statistically significant difference in the failure rates.


There was greater vital bone formation in the repaired sinuses compared to the non-perforated sinuses after augmentation.  When properly repaired, maxillary sinus membrane perforations do not appear to adversely affect vital bone formation or implant survival.

Dr. Gebrael’s comments:

Interesting enough we see more vital bone formation in the repaired sinuses after grafting.  The authors of the study indicate this may be due to the membrane over the perforation acting as a second barrier that prevents soft tissue migration and immobilizes the graft particles.

For more information please refer to:

Effect of maxillary sinus membrane perforation on vital bone formation and implant survival: a retrospective study.

Froum SJ, Khouly I, Favero G, Cho SC.

J Periodontol. 2013 Aug;84(8):1094-9


How Much Tissue Rebound After Crown Lengthening?



Sixty-four patients requiring crown lengthening on 64 teeth were included.  Bone was reduced based on the minimal amount of tooth structure required for restoration.  Patients were re-evaluated at 3 and 6 months.




There was significant soft tissue rebound (0.77 ± 0.58 mm) at 6 months post crown lengthening surgery.  The tissue rebound was significantly correlated with periodontal biotype: Thick-flat biotype experienced more tissue rebound (0.7 mm) than thin-scalloped biotype (0.37 mm).  Less tissue rebound was seen when the flap margin was further from the osseous crest after suturing.




Suturing the flap ≥ 3 mm from the osseous crest after surgery will minimize soft tissue rebound.  There was more tissue rebound and less crown length gained when a thick-flap biotype was present.


For more information refer to

Evaluation of supracrestal gingival tissue after surgical crown lengthening: a 6-month clinical study.

Arora R, Narula SC, Sharma RK, Tewari S.


J Periodontol. 2013 Jul;84(7):934-40

Are Short Implants (< 10 mm) Effective?


A meta-analysis on prospective clinical trials yielded thirteen studies with 1,955 dental implants, of which 914 were short implants < 10 mm in length.




Short implants had an estimated survival rate of 88.1% at 168 months, compared to a similar survival rate of 86.7% for standard implants (P=0.254).  The peak failure rate for short dental implants occurred between 4 and 6 years of function.  The peak failure rate for standard implants occurred between 6 and 8 years of function.




Similar long term survival rates for implants < 10 mm in length compared to longer implants.  When implant failure did occur, it was at an earlier stage for the shorter implants.


Dr. Gebrael’s Comments:

Bone augmentation procedures have limitations and may not be acceptable to many patients due to increases in cost, treatment duration, and site morbidity.  Short implants can be used with a good long term survival rate. This meta-analysis however was not able to determine the influence of bone density or type of prosthetic reconstruction on implant survival.




Are Short Dental Implants (< 10mm) Effective?

A Meta-Analysis on Prospective Clinical Trials


Monje A, Chan HL, Fu JH, Suarez F, Galindo-Moreno P, Wang HM

Journal of Periodontology July 2013, Vol. 84, No. 7, Pages 895- 904




Does Thread Design Influence Immediate Implant Positioning?


Two different thread designs were compared.  One group had a V-shaped thread design (Zimmer) and the other had a square-shaped thread design (Biohorizons).  Immediate implants were placed with a surgical guide in a randomized split mouth design.  The location of the implants after placement was measured to the closest millimeter.


All implants placed in extraction sockets tended to move facially compared to the initial drilling trajectory.  There was a tendency for square thread implants to be placed more facially compared to implants with a V-shaped thread but the difference between the two groups was not statistically significant.


Drilling against the inclined palatal wall of the socket has a tendency to shift the osteotomy facially and leads to a more facial positioning of the implant.  A V-shaped cutting thread design may help with reducing buccal displacement.  There was no significant effect of implant thread design on the positioning of the implants in this pilot study.


Implants placed with a buccally positioned shoulder exhibit three times more recession than those with a lingual position (Chen and Buser 2009).  The cutting design of V-shaped implant threads may help in engaging more of the palatal wall and may result in less buccal displacement of the implant.


for more information please refer to:

Influence of thread design on implant positioning in immediate implant placement.

Koticha T, Fu JH, Chan HL, Wang HL

Journal of Periodontology Nov 2012, Vol. 83, No.11, Pages 1420- 1424.


What is the Palatal Mucosa Thickness on a CT Scan?



CT scans taken from 100 subjects were evaluated.  Measurement points were taken from the gingival margin to the middle palatine suture at the canine, premolar, and molar sites. 




The mean thickness of the posterior palatal mucosa was 3.83 mm ± 0.58 mm.  

Thinner palate for females (3.66 ± 0.52 mm) compared to males (3.95 mm ± 0.6 mm).

Palatal thickness increased with age.  

The palate was thickest at the second premolar site and was thinnest between the first and second molars. 

There was an overall increase in the thickness of the palatal mucosa as we move towards the middle of the palate.




CT scans are a valuable source of data for measuring the dimensions of the palatal mucosa and are non-invasive.  The canine to premolar region has the most uniformly thick mucosa and seems the most appropriate donor site for connective tissue grafts.







Thickness of Posterior Palatal Masticatory Mucosa: The Use of Computerized Tomography

Song JE, Um YJ, Kim CS, Choi SH, Cho KS, Kim CK, Chai JK, Jung UW

Journal of Periodontology Mar 2008, Vol. 82, No.2, Pages 227- 233




How does Calcium Sulfate compare to Freeze Dried Bone Allograft for Ridge Preservation?


Thirty-one extraction sites were divided into the test group (Calcium Sulfate) and the control group (FDBA).  At three months, sites were re-entered, ridge dimensions were measured and bone samples analyzed for new bone formation.


Minimal change in the vertical ridge height for both groups.  Both groups had significant decrease in bucco-lingual ridge width (mean change ~ 1.0 mm) but there was no significant difference between groups.  An average of 32% new bone formation for Calcium Sulfate and 16.7% new bone formation for FDBA.


Calcium Sulfate is as effective as FDBA in preserving ridge dimensions after extraction.  There was more new bone formation and greater graft clearance for the Calcium Sulfate group.


A landmark paper that won the M. K. Hine award. Please note that this study excluded cases involving fracture of the buccal plate, dehiscence or fenestration defects. 


for more information please refer to:

A clinical and histomorphometric study of calcium sulfate compared with freeze-dried bone allograft for alveolar ridge preservation.

Toloue SM, Chesnoiu-Matei I, Blanchard SB

Journal of Periodontology July 2012.

When is it necessary to refer patients to an Ear, Nose and Throat Specialist prior to sinus grafting?


63 ENT specialists responded to mailed questionnaire that include various sinus pathology scenarios.  Their responses were statistically evaluated and analyzed.


58% recommend routine CT Scan prior to sinus-lift surgery.  

Patient symptoms that indicate referral to ENT prior to sinus grafting include nose problems and sinus issues.  

CT- scan findings that suggested a referral in the opinion of a majority of ENT specialists :  

1) Occluded sinus with septum.  

2) Inflammation at the base of the sinus only

3) Generalized thickened sinus membrane

4) Oro-antral fistula

5) Thickened sinus membrane in association with perio or endo involved teeth.

6 ) Near completely occluded sinus 

Other concerns included past history of sinus surgery, chronic sinusitis, ostium stenosis, nasal obstruction and oro-antral fistula 


A CT Scan prior to sinus-lift surgery was recommended by 58.7% of ENT specialists.  Their greatest concerns were prior sinus surgery, severe sinus inflammation, nasal/sinus obstruction and oro-antral fistula.


for more information please refer to:

New York State Ear, Nose and Throat Specialists view on pre-sinus lift referral.

Cote MT, Segelnick SL, Rastogi A, Schoor R

Journal of Periodontology Feb 2011, Vol. 82, No.2, Pages 227- 233. E-publication: 2010, September 1


Do multiple adjacent extractions affect implant bone levels?


Beagle dogs were assigned to three groups with 16 sites each:

Group 1: Single tooth extraction and one immediate implant

Group 2: Two adjacent teeth extractions and one immediate implant

Group 3: Three adjacent teeth extractions and one immediate implant 

Jaw segments were analyzed for bone thickness, marginal bone loss and bone to implant contact.


Group 3 (Three adjacent teeth extractions with one immediate implant in the middle socket) had the most severe buccal marginal bone loss (3.20mm compared to 0.375mm for Group 1 (single extraction and immediate implant). 


Multiple adjacent teeth extraction causes more extensive buccal bone remodelling and greater amount of buccal marginal bone loss around immediately placed implants.  This may be due to the severing of the interdental bone blood supply.


for more information refer to:

Alveolar Bone Remodeling Around Immediate Implants Placed in Accordance With the Extraction Socket Classification: A Three-Dimensional Microcomputed Tomography Analysis.

Munirah Saleh Al-Shabeeb, Mansour Al-Askar, Abdulaziz Al-Rasheed, Nadir Babay, Fawad Javed, Hom-Lay Wang and Khalid Al-Hezaimi

Journal of Periodontology August 2012, Vol. 83, No. 8.