DentistryUnited.com Newsletter

 


                    D e n t a l    F o l l i c l e               

             The        Monthly     E-newsletter                   Vol - I       Number- X II         May 2007

In this Issue:

  • Editorial

  • News

  • Laughter - The best Medicine

  • C-reactive protein— Part I - Dr. Vinayak Joshi

  • 5 Reasons You Should Be More Organized - Cathy Warschaw

  • Getting down to Roots of Dentistry - News Article

  • RASHA RECOMMENDS ............. : Dr. Rasha Seragelden

  • Laser Dentistry - A basic Comparison between Er:YAG and Er,Cr:YSGG - Dr. Maziar Mir

  • Evaluation of the efficacy of a collagen GBR membrane (BioMend Extend) supported by autogenous bone grafts,     for the treatment of peri-implant bony defects, during implant placement."Part III- Dr.Yousef Abd ElGhaffar
     

 

Editorial :

      Dear Fellow Dentist,                          

       We are one year old now! Dental follicle completes its first year with this issue . In this edition I have published some of the selected articles of the previous issues. In this edition we have acknowledged some of our well wishers without whom we could not have completed our first year.

    Back in the year 2004 www.DentistryUnited.com was launched as a platform for gaining and sharing knowledge. In 2006 we launched     "Dental Follicle" , our monthly E-newsletter , which now reached the mail boxes of more than 30,000 dentists across the globe. We thank you for your  support.

 

    I would like to thank a few special people without whose support dental Follicle would not have been possible -

  1. Our advertisers Rolence enterprises Taiwan . The company who makes world class products for dentists . Rolence Enterprises- Taiwan specializes in making dental equipments including Curing light , Curing light meter , Intra oral camera, Bleaching systems , Ultrasonic scaler , Ultrasonic cleaner ,Air turbine handpiece , Dental burs , Parts of dental unit and Disposable items. so next time you see ROLENCE in any conference , remember you first saw it on DentistryUnited and   

 

Dental Follcile  for enquiries Info@rolence.com.tw /  For Sales Enquiry contact Mr.Michael wang on michael_wang@rolence.com.tw

  2. Our techinical support Mr. Khalid Jaffar Syed who holds an Engineering degree in computer science. Presently a part time free lancer , providing IT services and solutions on .NET , J2EE and Oracle.An expert in Website design and support . He can be contacted on  Khalidjaffar@gmail.com  

 3 . Some of our other advertisers including One of India's Leadng dental Implant supplier  .For enquiries call Mr.Promeet Nanda on - +91-98231-79349+91-98231-79349

 

Click here to join DentistryUnited
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Yours truly

Dr.S. Nabeel

Editor of Dental Follicle & WebMaster www.DentistryUnited.com

News :

         

                       

Laughter - The Best Medicine :

A young Dentist had just started his own Clinic. He rented a beautiful office and had it furnished with antiques. Sitting there, he saw a man come into the front office. Wishing to appear the "busy dentist", the gentleman picked up the phone and started to pretend he had to give an appointment.

 Finally he hung up and asked the visitor, "Can I help you?"

The man said, "Yeah, I've come to activate your phone lines."

                                         

C-reactive protein— Part I

by- Dr.Vinayak Joshi

 

The very first response of living cells to injury or a noxious stimulus, anywhere in human body is inflammation. The inflammation is then followed by secrection of cytokines, mostly interlukines IL-1, IL-6, IL-8 and TNFα. The liver responds by means of releasing acute phase reactants. One of the most sensitive markers among the acute phase proteins is the C-reactive protein. Other acute phase proteins are proteinase inhibitors, coagulation factors, complement factors, transport proteins and miscellaneous proteins like the serum amyloid A protein.

 

C-reactive protein (CRP) derived its name from its ability to precipitate the somatic C-polysaccharide of Streptococcus pneumoniae. It is a member of the pentraxin family of proteins. CRP was originally discovered by Tillett and Francis in 1930 as a substance in the serum of patients with acute inflammation. The CRP gene is located on the first chromosome (1q21-q23). Human CRP is a calcium-dependent ligand binding protein, which binds with highest affinity to phosphocholine (PC) residues, as well as a variety of other autologous and extrinsic ligands, and aggregates or precipitates the cellular, particulate or molecular structures bearing these ligands.

 

In a healthy individual, the median concentration of CRP is 0.8mg/l, but following a stimulus it could rapidly increase by as much as 10,000 fold, with de novo hepatic synthesis, serum concentrations beginning to rise by about 6h, and peaking around 48h. The CRP levels also vary in relation to age and sex (females having slightly higher concentration). CRP levels accurately reflect the ongoing inflammatory process than any other biochemical parameters, in most if not all diseases. The CRP value is thus a very useful non-specific biochemical marker of inflammation, measurement of which contributes importantly to: (i) screening for organic disease; (ii) monitoring the response to treatment of inflammation and infection; and (iii) detecting intercurrent infection in the few specific diseases characterized by modest or absent acute-phase responses to those diseases themselves.

 

Functions:

CRP is a member of the class of acute phase reactants as its levels rise dramatically during inflammatory processes occurring in the body. It is thought to assist in complement binding to foreign and damaged cells and affect the humoral response to disease. It is also believed to play an important role in innate immunity, as an early defense system against infections. CRP is also thought to stimulate tissue factor production.

 

Measuring CRP:

 

CRP measurements are used to asses the active inflammation in sepsis or arthritis. High sensitive methods which allow detection of low level states of inflammation are important in CVD risk.

 

The following types of CRP assays have been cleared: by U.S. Department of Health and Human Services Food and Drug Administration

  • Conventional C-Reactive Protein (CRP)
  • High sensitivity CRP (hsCRP)
  • Cardiac C-Reactive Protein (cCRP)

The American Heart Association (AHA) has set a parameter for what is considered as normal hsCRP level:

  • If hs-CRP level is lower than 1.0 mg/L, a person has a low risk of developing cardiovascular disease.
  • If hs-CRP is between 1.0 and 3.0 mg/L, a person has an average risk.
  • If hs-CRP is higher than 3.0 mg/L, a person is at high risk.

If, after repeated testing, patients have persistently unexplained, markedly elevated hs-CRP (greater than 10.0 mg/L), other evaluation should be considered to exclude noncardiovascular causes.

As for getting ones CRP level measured this is what AHA has to say:

“If a person’s cardiovascular risk score — judged by global risk assessment — is low (the possibility of developing cardiovascular disease is less than 10 percent in 10 years, no test is immediately warranted. If the risk score is in the intermediate range (10-20 percent in 10 years), such a test can help predict a cardiovascular and stroke event and help direct further evaluation and therapy. However, the benefits of such therapy based on this strategy remain uncertain. A person with a high risk score (greater than 20 percent in 10 years) or established heart disease or stroke should be treated intensively regardless of hs-CRP levels.”

(The next post will discuss about the various disease and in specific relation of CRP to cardio vascular disease)

…..So understood by:

Dr Vinayak M. Joshi M.D.S ( perio)

( Dental Follicle Vol 1 , issue 3, August- 2006)

 

5 Reasons You Should Be More Organized

                                                              by- Cathy Warschaw

 

Some people think being organized requires a lot of work or maybe a complete system where you have to do a complicated set of tasks. In short, many people view being organized as impossible to achieve. While that is not really true, it takes a  disciplined person not to resort back to his/her old habits. It’s really easy to do and you get many benefits when you’re organized. Here are some of them.

 

1. You will have more room.

Being organized will provide you additional “uncluttered” space. You won’t need to necessarily throw anything out, you just need to place things in some sort of order and maintain that order at all times.

 

2. You will be able to save time.

Looking for files at work? It’s organized alphabetically in the cabinet. Being organized lets you look for files that you might need in a hurry in the future. Looking for your book? It’s safely stashed behind your bed. This is a really good time-saving technique which would help you when you’re in a hurry.

 

3. You will also save money.

You don’t believe that? Try thinking why you bought another ballpoint pen today? Isn’t it because you lost your old one? Or think of the countless items you bought because you thought you didn't have one of them at your house. Just think of how much you could save in a year just by being organized.

 

4. You will feel more in control.

Did you know that clutter around your house and at work causes the stress you’re feeling from time to time? It’s no wonder you’re feeling more irritated at work. As your clutter goes, you’ll feel that it is easier to breathe and take charge of your own life.

 

5. You will make a great impression to others.

This should be a good enough reason why you should make a considerable effort to be organized. Just think of your employer or office manager not pestering you to clean your work area again. Or just think how you’ll never forget that you have a scheduled meeting.

 

Being organized requires a lot of discipline to maintain. Nobody ever said it was easy. You need to make sure you don’t lapse back to your old habits or all of what you have done will be for nothing.

 

© Warschaw Learning Institute 2006

Cathy Warschaw is the Director of the Warschaw Learning Institute an online educational site offering; Dental Office Management Program, Telephone Training,  HIPAA and various e-books.  For more information go to www.WarschawLearningInstitute.com or call (323) 822-0917(323) 822-0917

(Above article originaly published in Vol 1 , Number 5 , October 2006 )

Getting down to Roots of Dentistry

               Egypt has been a land of contribution to the human civilization from 365 days calender to massive public projetcs and now evidence suggets the Roots of dentistry to be in Egypt.Archelologisits have found the tombs of three dentists

The pictorial letters also spell out the names of the chief dentist — "Iy Mry,  and assistants Kem Msw and Sekhem Ka Hawass"in SAQQARA, Egypt. The tombs were Curse protected  for 4,200-years--warngin :"Violate these tombs and you will be eaten by a crocodile and a snake".

Their location near the Step Pyramid of King Djoser — believed to be Egypt's oldest pyramid — indicate the respect accorded dentists by Egypt's ancient kings, who "cared about the treatment of their teeth,"

(Dental FollicleVol 1 , Number 6 , November 2006 )

 

RASHA RECOMMENDS .............  :

 The Issue of december 2006 was very special as Dr.Rasha Seragelden joined us with her recommendations! No doubt this young lady created a place for herself by giving some of the best links in the next few issues to come. I believe she is a "the intelligent , smart , resourseful dentist " to all the dentists who use internet to gain information and knowledge. Below is my write-up on her entry into the family of "Dental Follicle" and her first set of recommendations.

With This Issue we have a New person to provide you more information! I am sure if you are a member of any Dentistry related group you might have come across a person who sends maximum messages in the form of links! Links , that are better than just good! Some links this Lady sends have been appreciated by many members across various Yahoo-Groups!

             I am sure you have guessed the person , its Dr.RASHA SERAGELDEN

We are happy to introduce a new feature on Dental Follicle , RASHA RECOMMENDS! Where you will find the Links specific to specialty are recommended by Dr.Rasha Seragelden!In case you are looking for some information on  a specific topic/case , just mail us at Dentalfollicle@gmail.com and Dr.Rasha Seragelden will find it for you , which will be included in the next edition of Dental Follicle! ----  Editor!

  RASHA RECOMMENDS .............

 

Laser Dentistry - A basic Comparison between Er:YAG and Er,Cr:YSGG

Maziar Mir

DDS, MSc, PhD

Assistant Prof. ZPP, RWTH Hospital, Aachen, Germany



When the Hibst and Keller have published the first articles about the ablation of tooth with Er:YAG laser on 1989 in English journals (some years after German versions), nobody was estimating that in 8 years the speed of cut (Volume of ablation) could be practically
suitable for dental daily needs. On that time the 4-6 pulses per second were recommended and the laser was cutting the tooth very slowly. On 1995, the number of pulses increased to 20 and Er,Cr:YSGG was also introduced to American dental society on 1997. At the same year both wave lengths were successfully cleared with FDA and delivered to dental clinics to be used
as an adjacent to drills!

On 2000, the discussions about the basics of mechanisms were hottest topic of dental congresses and WATER role was under the focus of investigators. On 2002 a basic study started by the author in Aachen RWTH Hospital following the advance advises of Prof.Dr. Norbert Gutknecht and guidances of Dr. Leon Vanweersch, Dr. Joerg Meister and Dr. Rene Franzen.

The project was done with the help of two HIGH TECH cameras. First one was able to make up to 40500 pictures per second. So, as is seen in Figure-1, the author was able to monitor any pulse (with a length of 140-180 microseconds) with looking at about 30 pictures. Therefore, the accurate interactions between laser light, water and enamel were accurately visualized.

Both wave lengths of 2780 nm (Er,Cr:YSGG) and 2940 nm (Er:YAG) were irradiated in a distance of 1 mm in front to the enamel surface. The water selected as the media between laser tip and tooth. By this method, the different phases of any pulse interactions with first micrometers of water layer at the start of pulse were reported. There was no difference seen between two wave lengths not only at start of pulse, but also in the rest of procedures.

The most important finding is that the basics of ablation with both wave lengths are more and less the same and the important characters of both in increasing the speed of cut would be the duration of pulses and energy of any pulse, as well as suitable amount of water between the laser irradiating tip and tooth surface.

This research have been presented in 2nd international congress of Laser Dentistry in Dubai on 11th January 2007 by the author and is IN PRESS in one of the high rank ISI indexed scientific journals. For more information the interested persons could kindly write to: mir.maziar@gmail.com

As a conclusion could be addressed that there are enough evidence which show 30 pulses per second of both wave lengths with a pulse energy of 300 mJ and pulse length of 60-90 microseconds, could cut the enamel even faster than high speed drills. The accuracy of cut margins with NON-CONTACT laser handpieces could be comparable also for preparing the
bevels and shoulders in the aim of Veneer, Inlay and Onlay, or crown and bridge preparations.

Our master students are using this applications daily and we present the clinical procedures world wide by video online lectures as you could see in Figure-2. It is the wish of author to be able in near future make the direct video conference presenting live cavity preparations with same methods for the Indian friends as well. The ideas are most welcome and the positive
and negative comments are open to be discussed in the dental forum of this web site...

( Dental Follicle vol 1 number 10 march 2007)

           

Evaluation of the efficacy of a collagen GBR membrane (BioMend Extend) supported by autogenous bone grafts, for the treatment of peri-implant bony defects, during implant placement."

Part - III

Dr . Yousef Abd ElGhaffar ,   

BDSc, MDSc,  Cairo University, Egypt

Fellow of ICOI and Member of AAID.

Email : dr_yousefabdelghaffar@hotmail.com

 

 Besides having the same criteria of a non-resorbable barrier, special demands must be added to a resorbable barrier because of the bioresorption process. To some extent, the bioresorption process will always be associated with a cellular response from the surrounding tissue, irrespective of whether the material has been degraded by enzymatic activities or has been hydrolyzed. Since this process entails some inflammatory response, the subsequent inflammation should be minimal, reversible, and not interfere with regeneration. Moreover, the bioresorption process must be controlled so that membrane is maintained for a sufficient length of time to perform its function for tissue guidance during the initial healing period (Gottlow 1998).
Ideally, a bioabsorbable material should be safe, cost effective, easy to use, remain in place until regeneration has occurred, and not to interfere with newly formed tissue. Furthermore, they should be limited to areas with minimal gingival recession and sufficient width and thickness of keratinized gingiva, where primary closure is sure to be achieved (Becker et al., 1996). Bioresorbable barrier membranes used for GBR include collagen, oxidized cellulose and polylactic-polyglycolic acid co-polymers.
A study was carried out to evaluate the efficacy of polylactic acid and polyglycolic acid (PLA/PGA) resorbable membranes in conjunction with autogenous bone grafts when used for the treatment of implant dehiscences and/or fenestrations versus (e-PTFE) non-resorbable membranes. A slightly higher percentage of bone fill was found in the e-PTFE group (98.20%) than in the PLA/PGA group (88.56%), but the difference was not statistically significant (Simion et al. 1997).
Hurzeler et al. 1997 performed a study on GBR around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier made of poly D, L-lactid-co-trimethylencarbonate and non-resorbable (e-PTFE) membranes were used as a control group. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites. Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier.

Synthetic bio-resorbable membrane barriers were claimed to cause clinical problems. Infections and inflammatory reactions were observed around breakdown debris of Guidor membrane barriers (polylactic acid type) (Schmitz et al. 2000).
Among the bioabsorbable materials, collagen which is the most important structural protein component of the body, naturally bioabsorbable, with proven medical applications, the use of collagen as a biomaterial has been advocated based on several factors such as its favorable role in cellular development, wound healing, and blood coagulation (Zahedi et al. 1998).
Because collagen is the most abundant protein in the body the search for a biodegradable material has lead to the development of collagen membranes, which have been used in medical fields for decades (Chen et al. 1995).
It had been reported that there is a similarity between collagen in human skin and certain animal tissues. Since human body enzymes can degrade animal collagen, so animal collagen is attractive as a GBR barrier material. Collagen membranes currently available are of various subtypes, but usually fabricated with type I collagen derived from various bovine, porcine or equine animal sources and harvested from tendon or dermis (Tripletti et al. 2001).
Collagen barriers are manufactured using extrusion-coagulation and air drying which forms sheets of material from dilute collagen solutions. The collagen is dissociated, purified and reconstituted before final sheet forming to reduce the potential for antigenic response when the material is implanted. Most collagen barriers are cross-linked to increase their strength, extend their resorption time and reduce their potential antigenicity (Wang et al. 1998).
Collagen is bioresorbable. During enzymatic degradation it will incorporate with the flap to support the new connective tissue attachment. This may result in augmenting tissue /flap thickness to further protect underlying bone formation and prevent future bone loss. Unlike some acid-based resorbable membrane materials, it does not release acid byproducts into the wound areas as the material breaks down (Pitaru et al. 1989).
In order to evaluate the biocompatibility and resorption pattern of a human collagen graft material in both in vitro and in vivo, human collagen extracted from placenta was implanted subcutaneously in 10 Sprague Dawley rats. The graft was encapsulated by day 7 and was slowly resorbed over 56 days with minimal inflammatory response (Quteish et al. 1991).
Ideal barrier membrane should stay in place for at least 4 to 6 weeks before being surgically removed, so the bioresorbable membranes as collagen barrier membrane should not degrade before a sufficient time to enhance regeneration. Many steps have been taken to delay its degradation process. This could be achieved either by increasing their structural integrity by cross-linking or by delaying the degradation process using metalloproteinase inhibitors which inhibit metalloproteinases responsible for degradation. Various cross-linking techniques have been developed. These include ultraviolet light (Pitrau et al. 1988), hexamethylene diisocyanate (HMDIC) (Minabe et al. 1989 and Kodma et al. 1989), glutaraldehyde plus irradiation (Quteish et al. 1992), and diphenylphosphorylazide (DPPA) (Brunel et al. 1996 and Zahedi et al. 1998). The glutaraldehyde technique was reported to leave cytotoxic residue during the process and to overcome the drawback of this technique, the diphenylphosphorylazide (DPPA) technique was developed.


The use of collagen membranes has not yet been approved by the United States Food and Drug Administration (FDA) for treatment of dehiscences associated with implants due to lack of researches concerning this matter (Wang and Carroll 2001).
Some animal studies were carried out to evaluate the efficacy of collagen barrier membranes in GBR. In a pilot study, Colangelo et al. 1993, created through and through defects on the lateral aspect of rabbit mandibles and then treated them with either a cross-liked bovine tendon type І collagen membrane or no-treatment control. The histologic evaluation at 30 days demonstrated a nearly complete continuous layer of lamellar bone with osteoblastic activity in the collagen membrane-treated group compared to only fibrous connective tissue in the control group.
Another study was carried out in 1993 by Sevor et al. Buccal dehiscences were surgically induced in dog mandibles. Implants were then placed in a random pattern in both sides of the mandibles (two of each type of implant in each side of the mandible). A resorbable collagen barrier membrane (CollaTec) was placed around one pair of implants on each side. The other two implants on each side served as controls. The sites were examined clinically and histologically after 4 or 8 weeks to assess bone regeneration. At 4 weeks, the mean defect fill was 69.16% in the collagen membrane-treated group compared to 24.07% in the control group. At 8 weeks, the mean defect fill was 80.29% in the collagen membrane-treated group compared to 38.62% in the control group. The author also reported excellent wound healing at experimental sites in contrast to results with other materials. He suggested that as collagen products have been extensively utilized to heal burns and to dress surgical wounds, collagen has been found to be a chemoattractant for fibroblasts and connective tissue elements. Examination of certain histologic sections in the present study showed that bone and bone elements proliferated in close approximation to the collagen membranes.
Zahedi et al. 1998 performed a study to evaluate the potential of Calfskin origin collagen membrane (Paroguide) in the healing of mandibular bone defects. The experiment was carried out on 25 Wistar rats. After exposing the mandibular ramus bilaterally, 5 mm diameter full-thickness circular bone defects were surgically created. Defect on one side was covered by the membrane (experimental), the defect on the other side was left uncovered (control) before closure of the overlying soft tissues. In the 90 and 180 day animals, all experimental defects were completely closed. While in control defects, no statistically significant increase in bone regeneration was observed.
Francisco et al. 2000 have clinically evaluated an absorbable a porcine dermis origin collagen membrane (Bio-Gide) and a non resorbable (PTFE) membrane, associated with or without deproteinized bovine bone mineral xenografts (BioOss), for the treatment of ligature-induced peri-implantitis defects in dogs. The results showed percentage vertical bone fill with use of the resorbable membrane alone (21.78±16.19) and with the use of resorbable membrane together with BioOss (27.77±14.07). With use of non-resorbable membrane the percentage of vertical bone fill was (18.86±10.63) and with use of non-resorbable membrane togther with BioOss it was (19.57±13.36). However, he concluded that no significant statistical difference was detected among treatments.
A comparative analysis between two different collagen membranes to treat peri-implant buccal dehiscence defects in eight mongrel dogs was performed. The study compared Bio-Gide to BioMend Extend (Bovine tendon origin) collagen barriers, also the study included control sites which were left without barrier. Clinical reentry was carried out after 4 weeks and after 16 weeks. After 4 weeks the defect height was 3.08±0.10 mm in BioGide barrier group, 3.28±0.11 mm in BioMernd Extend barrier group, and 3.41±0.12 mm in control group. After 16 weeks the defect height was 3.29±0.12 mm in BioGide barrier group, 3.11±0.11 mm in BioMernd Extend barrier group, and 3.091±0.15 mm in control group. The sites treated with barriers showed higher percentage of bone fill and bone-to-implant contact, however, sites treated with BioMend Extend demonstrated significantly greater bone-to-implant contact than sites treated with Bio-Gide barriers (Oh et al. 2003).
Few clinical studies were carried out to evaluate the efficacy of collagen barriers for treating dehiscence defects around dental implants. Zitzmann et al. 1997 studied GBR using Bio-Gide collagen membrane versus (e-PTFE) for treating 84 exposed implant surfaces, both were supported with BioOss. Bone fill was achieved for the collagen membrane group was 92% against 78% bone fill for the (e-PTFE) membrane group. In the latter group, 44 % wound dehiscences and/or premature membrane removal occurred.
Paroguide collagen membrane was evaluated for GBR to treat patients with insufficient ridge width (less than 5 mm). The membranes were supported by collagen sponges to maintain the space buccally and lingually. The defects which demonstrated sufficient width for implant placement were 75%. Mean increase in the size of the crest was 2.5 mm (3 to 5.5 mm) (Parodi et al. 1998).
Another study was performed by Nemcovsky et al. 2000, where buccal dehiscence defects were treated with GBR procedures using resorbable Bio-Gide collagen membrane supported by bovine bone mineral after the placement of 28 implants in 21 patients. Mean defect area at the time of implant placement was 23.7 mm². Implants were uncovered 6 to 8 weeks later. The mean defect area at the time of uncovering was 0.7mm². The mean percentage of defect reduction (clinical bone fills) was 97%.
Carpio et al. 2000 compared the efficacy of a porcine-derived bioresorbable Bio-Gide collagen membrane versus an (e-PTFE) membrane for GBR using a bovine bone xenograft/autograft composite in defects surrounding dental implants. Defect size was recorded at stage 1 and 2 surgeries (performed 6 months apart). At baseline, the defect height in the group treated with collagen barriers had a mean of 4.63±0.49 mm and the defects width had a mean of 3.36±0.28 mm. The defects height in the group treated with (e-PTFE) barriers had a mean of 4.18±0.39 mm and the defects width had a mean of 4.36±0.40. After 6 months reduction in defect height was 2.65±0.61 mm and reduction in defect width was 1.95±0.60 in group treated with collagen barriers. The reduction in defects height was 2.26±0.61 mm and reduction in defects width was 2.65±0.56 in group treated with (e-PTFE) barriers.
Hämmerle and Lang 2001 carried out a study to evaluate efficacy of Bio-Gide collagen membrane supported by BioOss for GBR to treat buccal dehiscence defects around dental implants. The study included 10 patients. At baseline, the deepest extensions of the defects were located at the buccal aspects (mean 7.8 mm, SD 1.9 mm). At re-entry, the mean defect had decreased to 2.5 mm (SD 0.6 mm). This difference was statistically significant (P < 0.01). Initially, in 62% of sites the depth ranged from 0-3 mm, in 23% it ranged from 2-4 mm, and in 15% it amounted to more than 6 mm. Six to 7 months later, at re-entry, 95% of sites were 3 mm and less in depth and 5% ranged from 4-6 mm. Defect resolution, as assessed by the amount of coverage of the initially exposed rough implant surface reached a mean value of 86% (SD 33%). One hundred percent resolution was accomplished at 8 out of 10 implants, 60% at one and 0% at another implant.

Brunel et al. 2001 performed 7-year follow up for GBR prior to implant placement using Paroguide collagen membranes supported by hydroxyapatite (HA) crystals. The results showed bone filling at a treated sites and osseointegration rate of 86% after 7-year observation period. He concluded that these results confirm the possibility of regenerating bone by means of bioresorbable membranes, assuring at the same time the long-term success for implants inserted in regenerated sites.
Tawil et al. 2001 evaluated the efficacy of a bioresorbable collagen membrane (Bio-Gide) in combination with autogenous bone graft in the treatment of peri-implant dehiscences, fenestrations, or limited vertical defects. Autogenous bone was used in all cases to fill the defect and maintain the space underneath the barrier. The membrane absorbed the blood and easily covered and adhered to the underlying bone. It was not stabilized by any retentive means. Sixteen to 32 months postoperatively, the sites were re-entered and the amount of bone regenerated was measured. The mean defect height and width respectively were 5.28mm and 3.11mm at the time of the first surgery. At the time of second surgery the mean defect height and width respectively were 0.61 mm and 0.94 mm. The results showed significant bone gain (average 87.6%) in the treatment of peri-implant bony defects with Bio-Gide and autogenous bone.
Regarding the quality of bone gained through GBR by the use of collagen barriers, it was proved that collagen barriers provided qualitative bone regeneration comparable to the standard (e-PTFE) material as assessed by histological examination (Friedmann et al. 2002).
Zahran and Al-Shirbiny 2003 studied the efficacy of a bioabsorbable collagen membrane (BioMend Extend) in combination with decalcified freeze-dried bone allograft (DFDBA) in the treatment of peri-implant dehiscence defects. Ten patients having twelve endosseous implants with buccal dehiscence defects were included in the study. Surgical re-entry was carried out 6 to 9 months post surgically, in conjunction with abutment connection. The initial height of the dehiscence defects ranged from 3 to 6 mm with an average of 3.95 mm. On re-entry, the height of the residual defects varied between 0 to 1.5 mm with a mean value of 0.66 mm with an average of 84.76% ±11.81% of defect fill. Four defects out of 12 showed 100% vertical bone gain. The initial width of the dehiscence defects ranged from 2 to 3 mm with an average of 2.33 mm. The residual width of defects varied between 0.0 to 1.00 mm with a mean value of 0.08 mm.

(Dental Follicle Vol 1 ,  Number 11 ,  April 2007)