Prosthodontics 3 Notes PDF

Doctor: ‫صالح العموش‬ Writer: 2018 Corrector: ‫مايكل الربضي‬  Dental Implants in Prosthodontics History of Dental Implants: -Dental implants are not a new procedure. They have been used for the last 25– 30 years. -Implants are made of many materials including titanium (the orig...

Doctor: ‫صالح العموش‬ Writer: 2018 Corrector: ‫مايكل الربضي‬  Dental Implants in Prosthodontics History of Dental Implants: -Dental implants are not a new procedure. They have been used for the last 25– 30 years. -Implants are made of many materials including titanium (the original implants were made of it), ivory, hydroxyapatite, ceramics, etc. -Nowadays, there are thousands of available implant systems, in Jordan, we have >50 implant systems -Researchers have traced the beginning of dental implants to the ancient Egyptian and South American cultures since the 18th century. According to Scharer & Chen (1993), in the 19th- century dentists used many different types of alloplastic materials such as Gold, Porcelain, Ivory, and Indian rubber in an attempt to replace lost teeth. -During old times, they used to replace rich people’s teeth with poor people’s teeth and splint them together with gold wire 1) Greenfield (1913): Introduced an endosteal implant, which consists of two pieces of hollow basket made of Platinum, soldered with a supra-structure, where the crown is placed. -The technique eventually failed. 2)Stock (1939): Inserted the first Co-Cr screw-shaped implant in freshly extracted sockets, where he noted the need for PRIMARY STABILITY which is mandatory for any implant system, and without primary stability, 80% of dental implants might fail. However, his system also failed | Page 2 3)Formiggini (1947): Introduced the Spiral design. -no osseointegration, which is similar to basal implants it depends on mechanical lock of the screw in compact bone – not spongy bone. -It failed due to the high resorption rate The adjacent picture shows a basal implant: immediate placement implants with immediate loading done within 3 days. This is done without any surgery or pain. It has a high failure rate and causes a bad smell 4) Cherchieve (1962) introduced a double-helical design (Co-Cr). 5) Scialom (1962): Introduced a “street of needles” design, and he put a bladelike supra- structure on it. -Nobody knows whether they were inserted into the bone or gingiva (they were inserted in the mucosa only leading to inflammation). -They also failed because no osseointegration 5)Dahl (1943): Introduced the use of Subperiosteal dental implant in the clinical trial. Thereafter, modified by Goldberg &Greshkoff (1949). -This implant system still exists in the US. - It is made of a Co-Cr framework and is mainly used in highly resorbed lower ridges (shorter than 4mm, the shortest dental implant is 6 mm) -can’t be used in the maxilla -It used to be a highly traumatic procedure but it’s not nowadays. -A flap is opened from the retromolar pad to the retromolar pad exposing bone, An impression of the bone is taken, and a Co-Cr denture is designed. | Page 3 -The design should include four rods emerging from the gingiva to insert into the denture then a flap is opened again to place the implant -Nowadays, an extraoral scanner can get a 3D impression of the mandible, so the flap is only opened once. -There is no real osseointegration occurring and retention is purely mechanical as the implant sits on top of the alveolar ridge and the mech is covered with gingiva. 6)Linkow (1964): Introduced the Vent-implants made from Cr-Nickel alloy -he was against osseointegration, and with fibro-osteointegration (It is used for ridges that are narrow buccolingually) -It can be made of titanium or ivory (metal alloys) -Its design has a blade that is inserted in the bone and an abutment where the crown is placed. From above, sometimes, it’s connected to the natural teeth. Nowadays we can’t do this, because the implants are 4 times more rigid than natural teeth. -Blade implants still exist and are made from titanium, they work sometimes and achieve mechanical retention only. -It eventually failed | Page 4 7)Roberts & Roberts (1970): Introduced the Ramus Frame Implant, Tripod shape supported by the symphysis anteriorly and the ascending ramus posteriorly. -They were made in an attempt to replace the teeth of the lower arch with an overdenture attached to the frame. It also failed. 8)Small (1975): introduced Mandibular-Stable Implant, similar to trans-fixation screws used in fractures of the mandible or maxilla. -Two or three screws are placed using an extraoral approach (neck) -from submental to submental -(one of two implant systems placed using an extraoral approach) in the lower border of the mandible to the top of the alveolar ridge. -A supra-structure is added on top of the screws. An impression is taken, and an overdenture is fabricated to fit over it. -The system depends on a mechanical lock to stay in place. The system doesn’t exist anymore. 9)Bosker (1986): introduced Trans-mandibular Implant (TMI). -from canine to canine for severely atrophied mandibles posteriorly. | Page 5 - Due to compression and tension this system will increase bone level - when the mandible is resorbed, less than 4 mm - It is made from pure gold and is placed using an extraoral approach. - It is used when a conventional osseointegrated implant is not indicated (at that time, the shortest implants were 10 mm long). - It is a major surgical procedure done under GA, very expensive, and not frequently done. - It depends on a mechanical lock to stay in place. Seven screws are placed; three of them stay in bone, and four get exposed to the oral cavity. 10)Orthopedic Professor Branemark (1952 at university of Gothenburg and his team, more or less by chance they discovered the biocompatibility of Titanium in animals when they were investigating wound healing (He placed titanium plates in a rabbit’s femur but couldn’t remove them after a while except by using a chisel and mallet) -From the time till 1965 the Titanium material was subsequently subjected to further laboratory and clinical experiments. -In 1969, Branemark et al described the direct bone contact to a metallic surface as the Osseoinegration phenomena, followed by Professor Schroeder et al (1977) -We have today close to 600 different implant systems produced by at least 146 different manufacturers located in all corners of the globe. Last year alone, at least 27 new dental implant companies surfaced in the market. -Were these new implants really clinically documented? No, according to Albrektsson and Sennerby (1991), ADA 1996, Eckert and colleagues (1997) and to several authors -Any implant system should be recommended by the ADA, but most of them are not, because they are not followed up by an academic institution – they are not subjected to specific criteria (5-year follow-up in 2 or 3 recognized dental centers with 75% success rate after 5 years Osseointegration Histological definition: is a process of direct structural and functional connection between living bone and the surface of the alloplastic material which is achieved during functional loading at a microscopic level. It is also called “functional ankyloses”. Branemark et al (1969), Shroeder et al (1977) Clinical definition: a time-dependent healing process. Clinically asymptomatic rigid fixation of alloplastic material which is achieved and maintained in bone during functional loading. Zarb and Alberkston (1991) Fibro-integration This is the second school. They believe that there should be fibrous tissue between the interface of the implant and bone mimicking the PDL. The failure rate was more than 75% after 5 years. (016): Their debate was that there should be a gap (connective tissue) between the alloplastic material and bone resembling the PDL. The PDL allows the slight movement of the tooth laterally and apically. Osseointegration, on the other hand, doesn’t allow movement. Implant Materials Many different metallic materials were tried to replace the natural missing teeth such as Gold, Stainless steel, Silver, Platinum, Iridium, and titanium. In addition to nonmetallic materials such as Indian rubber, Ivory, porcelain, Polymers, Ceramic, carbon, and Zirconia; it was introduced recently as an implant material. The Dr talked about Roxolid; it is composed of approximately 15 % zirconium and 85 % titanium. | Page 7 Pure Titanium (it is 99.6% Ti and 0.4% Ni, Ni is a corrosion-resistant alloy) It is the material of choice for osseointegration dental implants because: 1. Biocompatible with the living tissues. 2. Excellent mechanical properties "It is 6x stronger than the cortical bone once it is osseointegrated". 3. Histological section showed intimate contact between bone and implant surface. 4. Corrosion resistant 5. The chemical properties of Titanium are determined by the surface oxide layer which has different chemical, physical and mechanical properties from Pure Titanium. Although it has been shown that the Ti-Oxide surface undergoes minimal changes in the biological environment over a period of time extending up to several years. 6. Safe and inert material: After research, Ti ions were found adjacent to bone and in peri-implant mucosa and they were also found in the regional lymph nodes as well as other organs such as the liver, spleen, and kidney. It is not being absorbed or causing poisoning. Studies showed it is difficult to estimate the release of Ti-ions from implant surfaces accurately because Ti-ions also enter the body in many chemical forms each day via various foodstuff. The average Ti. Intake in humans /day is (0.3-1 mg) and the daily excretion rate is (0.3 mg) through urine. The biological half-life of Ti is (320days) which is too short to accumulate in the human body. Superior corrosion and wear resistance High IMPLANT COATING MATERIALS These materials have been introduced to produce a roughened surface to the implant fixtures, as it has been reported that the roughened surface provides an increase in the strength of the implant-to-bone bond when compared to a smooth surface. A. Titanium-Plasma-Spray (TPS): They processed them at very high temperatures (about 3000° C). It was used until the end of the 90s, and we had to wait for at least 5 months for maxillary healing, and 3 months for mandibular healing. It isn’t used anymore. B. Sand-blasted-Long grit-Acid-etched (SLA): Healing time (osseointegration) is reduced to the half → 2.5 months in the maxilla, and 1.5 months in the mandible. It is still used nowadays. C. Bioactive materials (SLA active): It takes 2 weeks of healing time in the mandible, and 3 weeks in the maxilla, but it is very expensive (double the price of SLA). D. Hydroxyapatite coating: It is an excellent material, it was used as synthetic bone material for small localized or limited defects/undercuts. It was used since the mid-1980s. *Advantages: -Rapid Osseo-induction. (Within months) -High success rate in the first 3-years. *Disadvantages: -After five years of function, high failure rates. -It shows cracks or even completes loss of coating. -Invasion of heavy colonization of micro-organisms: through the cracks down to the bone causing peri-implantitis> resorption and failure. methods of coating Sand-blasting Acid-etch method method Laser method |P a g e 9  The most widely classifications of dental implants make reference Classification of oral dental implants to their forms and positions Intra-mucosal Ti Mucosal Sub-periosteal Trans-osseous End-ossous implants insert implants implants implants 1) Sub-mucosal implant insert: It consists of a buttonlike retention device inserted underneath the mucosa of the residual ridge This type of implant has been largely discontinued. *Disadvantages: -Poor retention -Short survival rates. -Trapped food debris -Regular occurrence of acute bacterial infection. (016): They are inserted underneath the mucosa after the elevation of a flap (it is not placed in the bone itself, just above it and under the gingiva). It consists of a button-like retention device – a male and female part (one in the connective tissue and the other on the fitting surface of the overdenture). - it has been forbidden. | P a g e 10 2) Titanium mucosal insert: They have the same idea, but part of it is a few millimeters (2 – 3 mm) in the bone. The bone is drilled using different drills to achieve the minimal preparation required. It has the same male/female parts idea. It is no longer being used. you need to put many of them in order to gain retention, so it is not recommended to be used. 3) Sub-periosteal implants: It consists of a metallic framework placed directly on the superior surface of the bone jaw and kept in place by the overlying periosteum. Restricted only to the mandibular arch, low success rates with time; the possibility of spreading infection along the path of the metal frame beneath the mucoperiosteum may be led to bone resorption. (016): *An incision is made from one retromolar pad to the other. A flap is reflected, an impression is taken, and a cast is poured. The implant is then designed and adapted to the cast. *The flap is reopened (major surgery) and the framework is inserted. The framework has posts projecting inside the oral cavity. An overdenture will fit on those posts. *This type of implant is done when conventional endosseous implants can’t be used. In the past, 8 mm dental implants were considered short, but nowadays, 4 mm implants are the shortest available. *4 mm implants have certain indications like when the patient refuses ridge augmentation, the implant is close to vital structures, or the patient is highly compromised *The diameter compensates for length. The shorter the implant, the wider it is. As we said before, nowadays, an extraoral scanner can get a 3D impression of the mandible, so the flap is only opened once. | P a g e 11 4) Trans-osseous implants: These are inserted through the full thickness of the mandible, particularly in the extremely atrophic mandible (less than 4 mm), and when we don’t want to go for advanced surgery, like ridge augmentation. A. Mandibular Stable Bone Plate implants (MSBP). B. Trans-Mandibular Implant (TMI). -Both need G.A. -Limited to the lower jaw. -Needs an extra-oral surgical approach. -Major surgery (old patients). -Resulting in an extra-oral scar. (from submental to submental) It is made from pure gold. 5) Endosseous implant classification depends on the number of surgical steps: 1. One surgical step (ITI by Straumann).: non-submerged, there is a gingival former in the oral cavity. 2. Two surgical steps (Branemark system): submerged, you have to perform a second surgery to place the gingival former. Branemark did a comparison between the submerged and non-submerged systems and did not find a significant difference between them, however, one step is better for the patient, because you don’t have to do a second surgery, but they say that it might increase the risk of infection. The doctor counted a lot of implant brand names. They are all essentially the same, and now there are more than 1000 implant systems available. a. Branemark system (Noblepharma), Nobel Biocare: Brånemark / Replace / Nobeldirect / Nobelperfect. b. Implants systems based on Branemark system, such as steri-Oss, Astra, IMZ (not available anymore), Tubingen ( Dentsply: Frialit1 / Frialit2 / Frialit+ / Friadent / Frialoc / Frios / Xiv), Bicone, Piteasy,3i. Biomet 3i: Osseotite / Nanotite, Zimmer: Calcitek / Integral / Omniloc , Biohorizons,. Sweden&Martina etc…. Frialit 1 + Frialit 2 they were made from ceramic and it cracked when it was used, so no longer available Calcitek is one of the worst systems A comparison between the implant and the natural tooth ‫ﺑﺎﻗﻲ ﺍﻟﺷﻳﺕ ﻣﻘﺗﺑﺱ ﻣﻥ ﺷﻳﺕ‬016‫ﻻﻧﻪ‬..‫ﻣﻊ ﺑﻌﺽ ﺍﻟﺗﻌﺩﻳﻼﺕ‬ ‫ﻣﺵ ﻛﺗﻳﺭ ﻭﺍﺿﺢ ﺑﺎﻟﺭﻳﻛﻭﺭﺩ‬ Root Form of Implants Since the introduction of the Osseointegration by Dr. Branemark, Titanium Screw implants have become the most popular implants worldwide - Bone level and tissue level The bone level implant ends at the level of the crest of the alveolar ridge and is only 0.5mm above the bone. The tissue level implant extends 1.5 mm above the bone. The part that extends above the bone is a smooth collar. Nowadays, the bone level implant is used. The doctor uses the tissue level implant in posterior areas when there is a lot of keratinized mucosa as it has a better emergence profile. The bone level implant is used when we have a missing 6, for example, and the 5 and 7 abutment teeth have drifted causing a decrease in the mesiodistal dimension. It is also used when we have a limited amount of interarch space (like when the opposing tooth is slightly over-erupted). It is also more esthetic since the collar is 0.5mm, so it is used in the anterior area The implant used to be one piece; the fixture and the abutment were connected, but they are now different parts. The abutment has different angles ranging from 5° to 30°. There is also a straight abutment (with no angulation). The abutment angulations allow you to compensate for any angulation mistakes made during the insertion of the fixture. IMZ (German system), which is no longer available, was the first system that allowed implants to be connected with natural teeth. There is no research done on it, and the doctor hasn’t seen it since the year 2000. The root is cylindrical in shape and has a plastic intra-mobile element that allows slight movement. This element mimics the PDL and acts as a stress breaker → | P a g e 13 prevents harmful effects on the connected natural tooth, but we have to change this element every 8 months. Normal endosseous implants can never be connected to natural teeth as they cause them to drift. This is because titanium is 6X stronger than cortical bone. * There are implants with a taper; narrow apically and wide coronally. * Branemark system is characterized by the threads on the implant. Bone and tissue level implants Bone level implants Hydroxyapatite-coated Ivory imp implants. Before talking about indications and selecting the proper candidate for implant treatment, two points should be considered: A. Patient motivation and cooperation toward maintaining good oral hygiene. So, not fair but good or excellent OH. As any gum diseases (gingivitis or periodontitis), especially in partially edentulous patients, will be transmitted to the implant resulting in peri-implantitis. Scaling is done then the patient is monitored for at least 1 month, if good OH is maintained then implants can be done. B. Bone growth for the alveolar ridges "preferable after the age of 18-years. 19 years and above when bone growth is stopped is preferable for implants to be in the safe side same as conventional crowns. Clinical trials were done on ages below 19 years old, where they placed implants and crowns in 18 or 16 years old, at these ages bone growth is still in progress and it’s better to wait until it’s stopped to place implants. Bone growth takes a longer time (stop in later age) in males than females. |Page2  Indications for dental implants 1. Completely edentulous individuals in both or one arch If more than 6-fixtures, we’ll go for: implant supported prosthesis (fixed bridges). If more than two fixtures: implant-retained overdentures either by bar, ball or magnetic attachments. This is a full arch rehabilitation, 8 implants placed for an upper supported prosthesis. This is a severely resorbed lower ridge where it’s difficult to make a conventional CD, so two implants with ball attachments were placed for an overdenture. This is the overdenture, you can see the female part that is made of gold, it’s called matrix as it has sleeves, and you can activate it by screwdrivers if it’s loose and de-activate it if it’s tight with another screw. |Page3  2. Partially edentulous individuals I. Long span where it is not possible to be restored by means of conventional bridge. Like in this case from the canine to the second molar. You either go for RPD or if there is good quality and quantity of bone and the patient is healthy and willing you can place implants. *These implants are one unit, they are not connected to the canine or molar (we can not connect implants to the natural teeth due to osseointegration and they are stronger than natural teeth by 4 times). II. In case of Kennedy Class I where there is no anatomical contra-indication. III. Tooth replacement where the patient refused to prepare the adjacent sound teeth. Especially in the esthetic area. |Page4  IV. Patients with compromised denture bearing area which may reduce the retention. In the mandible we have the problem of highly atrophied ridge, so mostly two implants are placed between the canines or inter-mental foramina area as we always have good bone there, also they consider it as the safest area due to absence of any important vital structure there. V. Patients with hyperactive gagging reflex elicited by the removable prosthesis. The doctor mentioned a case of a patient with a severe gag reflex that they had to do all the steps of implants placement and prosthesis insertion under GA. VI. Patients with psychological and emotional problems to wear dentures. VII. Unrealistic Prosthodontics expectations. VIII. Para-functional habits. The forces generated during bruxism → bone healing → implant failure. This is due to the over prolonged lateral movements not centric. IX. Poor oral muscular coordination. Especially for Parkinson’s and epileptic patients. X. Hypodontia.. |Page5  Contraindications for dental implants 1) Intra oral contraindications: 1. Unfavorable inter-arches relationships i.e. skeletal class III. 2. Pathological lesion in the alveolar ridge i.e. infected remaining root, cysts, abscess. 3. Pathological conditions of the oral mucosa such as Leukoplakia, Lichen planus…etc. 4. Poor oral hygiene. Acute gingivitis, enlargement in epileptic patients like in the adjacent figure -> You need to refer them to oral medicine department. 2) Relative contraindications: 1. Insufficient and poor bone quality and quantity. 2. Hematological diseases i.e. Anemia ↓ RBC all result in post-operative infection and delayed healing and failure of osseointegration. 3. Metabolic bone disorders such as Osteoporosis "spongy bone" and Paget's disease "Sclerotic bone". 4. Patients with psychological problems. The doctor considers this an absolute contraindication. They should be referred to the clinical psychiatric then if they’re convinced you can place the implants and proceed with your treatment. |Page6  5. HIV +ve patients. Not contraindicated if you take the necessary precautions, especially that not all patients are honest about their medical history. 6. Age?? "Life expectancy". There is no age limit. 7. Radiation therapy. August et al (1998): no longer an absolute contraindication to implant placement, but reduced success rates (usually reported around 70%) can be expected. Use of hyperbaric oxygen therapy (HBO): 100% pressurized oxygen for proximately 90 min. for 20 sessions pre-surgery and 10 post-surgery. Oral effects of radiation: o Xerostomia. o Mucositis. o Hypovascularity. o Fibrosis. o Hypoxia. o Osteoradionecrosis. 8)DIABETES It is preferable to do it for controlled diabetic patients while in uncontrolled patients delayed wound healing, increased alveolar bone loss, increased periodontal disease and increased inflammatory tissue destruction may happen. Several studies have shown success with dental implants in patients with controlled diabetes. ( good for patient with HbA1c up to 7 with good oral hygiene but above that problems we mentioned before happen) 9)Osteoporosis Bisphosphonates & Paget disease Correlation between systemic bone loss and the loss of jawbone density and quantity has been shown, there was NO link established between systemic osteoporosis and implant failure. Becker et al 2000 |Page7 Bone deformities and pathological fractures caused by PD may render the use of removable prostheses. Dental implants significantly improves quality of life of PD patients  In an overview 2008, the American Dental Association had stated" The risk of developing BONJ (bisphosphonate- associated osteonecrosis of the jaw) in patients on oral  bisphosphonate therapy appears to be very low...". So, oral bisphosphonates and intramuscular is a relative contraindication, we should wait for 3-5 mon then we can start our procedure, while IV bisphosphonates are an absolute contraindication (forever) because it causes BRONJ. Remember!!:Bisphosphonates are a class of drugs that prevent the loss of bone density, used to treat osteoporosis and similar diseases. 10) Heavy Smokers (In the past we thought it had a relative contraindication but now we found that it has a high failure rate !) *Smoking is considered as a major risk factor for periodontal diseases and Arteriosclerosis". Has a deleterious effect on wound healing (especially after tooth extraction). Bain 1996 protocol Minimum of 1 week prior to and at least 8 weeks after implant surgery smoking should be stopped. *Generally, patients should be informed about the reduced success rate to be expected and advised to stop smoking permanently so they can get higher predictability of implant success. |Page8 3) ABSOLUTE CONTRA-INDICATIONS: 1- Patients with cardiovascular diseases especially congenital heart disease, like rheumatic valvular defect. *Severe hypertension is not an absolute contraindication *Artificial valves, even if we give prophylaxis, are absolutely contraindicated, but stents are not. *If the patient has angina pectoris and recent myocardial infarction we can do implant surgery for them but we have to wait at least for one year after that so a dental implant can be done, and we still give the patient prophylactic measures and take the consent and referral from his cardiologist. 2- DRUG & ALCOHOL ADDICTION Drug/alcohol themselves are not contraindicated. But due to Patient’s lack of commitment to long-term health and the questionable ability to maintain good oral hygiene. Biologically; little evidence that chemical addictions can alter the successful integration of implants.