Category Archives: Contemporary Implant Dentistry Edwin

In the books of E.C. Ltd

 Repossession of a part of the Asset

The·hire vendor, however, may not be’ harsh enough to take possession of the entire asset. He may leave some portion of the asset with the hire-purchaser. In that case; the purchaser should leave’ the proper balance in the account of the asset, representing the present value of the asset stillin hand and write off the balance.

Illustration 7. X Transport Ltd. purchased from Delhi Motors 3 trucks costing Rs. 5,00,000each on the hire ,purchaSe system. Payment was to be made Rs. 3,00,000 ~ and the remainder in 3 equal instalments together. with interest @ 18% p.a. X Transport Ltd. wrote off depreciation @ 20% on the diminishing balances. It paid the instalment due at the end of the first year but could not pay the next. Delhi Motors’ agreed to leave one truck with the purchaser, adjusting the value of the other 2 trucks against the amount due. The trucks were valued on the. basis of 30% depreciation annually on diminishing balances. Prepare .the .necessary ledger accounts in the books of X Transport Ltd. for 2 years. Also show journal , entries for all the transactions taking place on the date of default.

Postsurgical Dental and Periodontal Conslderatlons
. The patient should be seen for a maintenance dental and periodontal evaluation approximately 10 to 1-1 weeks postoperatively. The mucoglngtvat status is reevaluated, the mouth deplaqued, and areas of inflamma’tion or
pocketing lightly instrumented. ‘frequent recall maintenance should continue during the remainder of orthodontic care when necessary. After the orthodontic appliances are removed, a thorough prophylaxis with a review
of oral hygiene techniques is advisable. A thorough periodontal reevaluation 3 to 6 months after completion of the postsurgical orthodontics will determine future treatment needs. Periodontal surgery, including crown-”
lengthening or regenerative procedures, should be performe fter the intlammation associated with orthodontic appliances has resolved, Areas of hyperplastic tissue should be observed for 3 to (;)months after ‘orthodontic
therapy, unless esthettc or restorative considerations necessitate earlier tissue removai. After completion of periodontal treatment, recall intervals should be adjusted to accommodate the individual patient’s needs.

Postsurgical Restorative and Prosthetic Considerations

‘When patients require cornplex final restorative treatment, it is important to establish stable, full-arch contact as soon after orthodontic debanding as possible. Posterior vertical . contacts are important in patients who have only anterior components of occlusion remaining. \Vell-fjttin~, temporary.
removable partial dentures may suffice, and these appliances should be relined with tissue-conditlonlng materials as needed to maintain the posterior support dur- ‘Ing healing. When postsurgical orthodontics is complete, . the remainder of restorative treatment can be accomplished in the same manner as for any nonsurgical patient.

 

 

Extraoral Implants

Recognizing the success of implants for oral applications. maxillofacial prosthodontlsts and surgeons have expanded  use of titanium fixtures to extraoral application. Extraoral implants are now used to anchor prosthetic
ears, eyes, and noses for patients with defects resulting from congenital conditions, trauma, or pathology

Early Loading

have been efforts to define the minimum time required for osseointegration. Generally accepted integration times • are based on experience and tradition with little experimental data. Researchcontinues to attempt to define ideal minimum integration times. Factors that are likely important in determining what these minimum times should be   include: bone quality, implant.material, and surface and prosthesis configuration. Some studies have shown that early loading (i.e., 6 weeks) is.successful when 5 implants in the anterior mandible are rigidly-connected in a supporting framework. The most extreme variation on the theme of early loading is immediate loading. The Novum system relies on a jig to ensure exact implant position with a prosthesis supported by a machined titanium superstructure that is placed the same day as the implants

 

Implants in ‘Irradiated Bone

Ca~cer patients frequentiy suffe~’ from surgery- and irradtatton-assoclated soft and hard tissue defects that signlficaritly compromise conventional prosthodontlc rehabilitation. “An implant-supported prosthesis’ could improve function and esthetics: however, concern regarding the compromised wound healing that results after .turnoricidal irradiation to the jaw~ has contraindlcated even minor surgery and Implant placement in these patients. It new appears that it may be possible.to place irriplants in this ‘group of patients. Careful soft tissue himdling and perioperative hyperbaric oxygen’treatments. have been used for patients receiving; implants in Irtadi

ated tissue, with results comparable to thai: found in non rradiated patients. Little is known about the long-termresults in thes  patients, and potential for increased faiure and serious sequelae (e.g., osteoradionecrosis) still
exists. Asa result, an experienced implant surgeon shouldmanage implant placement in this group of patients.

 

Atrophic Maxilla

Initial implant restorative approaches for the fully edentulous maxilla concentrated on implant placement in the anterior- region, simllar to the edentulous mandible. However, the resulting prosthesis was often unsatisfactonry, If adequate space was allowed for proper hygiene,
phonetics and esthetics were severely compromised, If the prosthesis was developed in such a way as to eliminate these, problems, hygiene became virtually impossi- ‘ble. The cantilever effect of this type of prosthesis on
implants placed w thin the compromised bone of the maxilla also resulted in increased failures. If implants are ‘placed bilaterally in the posterior maxilla, a prosthesis , ‘ wlthldeal esthetics, phonetics, and hygiene access can be , -created.: However, the ‘bone overlying the sinus is frequently
inadeq ate to place the implant and to allow , .suitable bony support. In these situations the sinus floor may be, grafted to. increase the quantity of bone for implant placement. , . Some patients are unwilling to wait the time required for sinus lift’ consolidation or are unwilling to undergo grafting.,A relatively new technique that places very long implants into the. body of the zygoma (Zygomaticus system), ‘along with short anterior implants, is an effective  way to support a maxillary overdenture without need for sinus lift surge~ (Fig. 14-67).

Atrophic Posterior Mandible

As,discussed earlier, the posterior mandible poses unique appealing.  vidence suggests that implants can be sueproblems.
Presence of the inferior alveolar nerve 1imits ‘ cessfully placed into growing  atients. In the fully edenimplant length. This, coupled’ with increased. ocdusal . . tulous ‘patient, an implant-supported prosthesis can be
load, is one reason for the higher implant. failure rate in . fabricated as soon as the patient is old enough to cooperthis region. Overengineering with placementof- more ate with-hygiene requirements. This is usually defined as   plants can improve the prognosis. When less than 8 ‘age 7: Inpatients who have lost a portion of the jaw from mm of vertical height overlying the interior alveolar tumor resection or ‘tra ma, an implant-supported prosnerve is found, implant success will be severely cornpro- “. thesis can likewise be used as early as age 7. However, mised, Bone may be grafted to increase height as previ-· when .the edentulous area in question is ssociated with ously described. unerupted natural teeth, no implants should be placed However, if supereruption of the posterior maxillary until eruption of the’ natural dentition and alveolar dentition exists, a graft of, adequate thickness to . ‘growth -are complete (i.e., at approximately 16 years of
improve implant stability may result in inadequate” -age). Implants placed before this will behave in a similar interarch space for the prosthesis, In this case the infe-‘ .fashion to an ankylosed tooth, with progressive submerrior
alveolar nerve may be repositioned to ‘allowuse of sion’ of the implant as a resu\.t of eruption of adjacent the entire height of the mandibular body (Fig: 14-66). tee~~ and alveolar bone growth., . IThis procedure carries the risk of p.ermanel1t anesthesiaor painful dysesthesia. The magnitude of this ‘compltcation requires that a surgeon experienced withnerve surgery
and postoperative assessment of- neurosensory .function perform this operation, The advantage is thatwith repositioning of the nerve a longer Implant ca ‘be placed, with stabilization in both the superior and inferior
cortical bone. .

Atrophic Anterior Mandible

In the atrophic mandible (l.e., less than ‘8 mm of vertical height), the shortest implant may be longer’ than the available bone. Implants may be placed by purposefully perforating the inferior cortex. This’ may decrease the crown-to-root ratio or increase th, risk of “fracture .’ Recent studies have shown that afte. restoration ‘ofthe. atrophic mandible with an entirely implant-supported prosthesis, bone height and density increase, presumably as a result of the functional stresses that result horn the
prosthesis. Therefore an effective approach in the atrophic’ mandible is to place five implants, leaving 2 .to 3 rnm above the height of the residual bone. An entirely implantsupported hybrid prosthesis is then fabricated. Alternatively the transmandibular implant (TMI) has also been shown to be effectIve in the very atrophic mandible, with’ similar remodeling and formation of new bone. Either of  these techniques may be considered in ·the atrophic mandible where 6 mm or more of bone height is’ found If the bone height is less than 6 mrn, augmentation of the .bony height in this area with autogenous gratis may be necessary. Autogenous grafts onlayed onto the residual ridge will undergo resorption if conventional dentures are placed but are generally maintained well if an implant-borne prosthesis is placed.

Anterior Maxilla Esthetic Zone

In the esthetic zone of the anterior maxilla, successful integration alone is not adequate. The implant must have proper position, angulation, and depth for esthetic restoration. These parameters are prosthodontically determined and communicated to the surgeon by the surgical stent. TIie stent must show the ideal position; labial thickness of porcelain and metal; and location’ of the CEl of the final prosthesis. If inadequate bone is present to place the. implant with proper position and angulation, grafting is necessary. Esthetic concerns and compromised bone often pr sent in the situation of congenitally missing teeth. Fail- . ure of tooth formation is associated WIth severe hypoplasia of the alveolar bone. Grafting using either guided bone regeneration tee niques or corlicocancellous blocks must be considered (see Fig. 14-61). Implai.t depth is also important to allow proper “me ge .ce profile. Excessive depth will lead to increased pocket depth, and too shallow placement can result in a poorly contoured crown or metal showing at the gingival margin. As a general rule, the top of the Implant should be placed 3 mm below the planned position of the CEl of the final restoration.